Legal Authorities Supporting the Activities of the National Security Agency Described by the President

Legal Authorities Supporting the Activities of the
National Security Agency Described by the President
The activities described by the President, in which he has authorized the National Security Agency to
intercept international communications into or out of the United States of persons linked to al Qaeda
or an affiliated terrorist organization are lawful in all respects.
The President’s use of his constitutional authority, as supplemented by statute in the Authorization for
Use of Military Force enacted on September 18, 2001, is consistent with the Foreign Intelligence
Surveillance Act and is also fully protective of the civil liberties guaranteed by the Fourth Amend-
ment.

January 19, 2006

LETTER FOR THE MAJORITY LEADER
UNITED STATES SENATE

Dear Mr. Leader:
As the President recently described, in response to the attacks of September
11th, he has authorized the National Security Agency (“NSA”) to intercept
international communications into or out of the United States of persons linked to
al Qaeda or an affiliated terrorist organization. The attached paper has been
prepared by the Department of Justice to provide a detailed analysis of the legal
basis for those NSA activities described by the President.
As I have previously explained, these NSA activities are lawful in all respects.
They represent a vital effort by the President to ensure that we have in place an
early warning system to detect and prevent another catastrophic terrorist attack on
America. In the ongoing armed conflict with al Qaeda and its allies, the President
has the primary duty under the Constitution to protect the American people. The
Constitution gives the President the full authority necessary to carry out that
solemn duty, and he has made clear that he will use all authority available to him,
consistent with the law, to protect the Nation. The President’s authority to approve
these NSA activities is confirmed and supplemented by Congress in the Authoriza-
tion for Use of Military Force (“AUMF”), enacted on September 18, 2001. As
discussed in depth in the attached paper, the President’s use of his constitutional
authority, as supplemented by statute in the AUMF, is consistent with the Foreign
Intelligence Surveillance Act and is also fully protective of the civil liberties
guaranteed by the Fourth Amendment.
It is my hope that this paper will prove helpful to your understanding of the
legal authorities underlying the NSA activities described by the President.

ALBERTO R. GONZALES
Attorney General

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WHITE PAPER *

As the President has explained, since shortly after the attacks of September 11,
2001, he has authorized the National Security Agency (“NSA”) to intercept
international communications into and out of the United States of persons linked
to al Qaeda or related terrorist organizations. The purpose of these intercepts is to
establish an early warning system to detect and prevent another catastrophic
terrorist attack on the United States. This paper addresses, in an unclassified form,
the legal basis for the NSA activities described by the President (“NSA activi-
ties”).

I. Summary

On September 11, 2001, the al Qaeda terrorist network launched the deadliest
foreign attack on American soil in history. Al Qaeda’s leadership repeatedly has
pledged to attack the United States again at a time of its choosing, and these
terrorist organizations continue to pose a grave threat to the United States. In
response to the September 11th attacks and the continuing threat, the President,
with broad congressional approval, has acted to protect the Nation from another
terrorist attack. In the immediate aftermath of September 11th, the President
promised that “[w]e will direct every resource at our command—every means of
diplomacy, every tool of intelligence, every tool of law enforcement, every
financial influence, and every necessary weapon of war—to the disruption and to
the defeat of the global terrorist network.” Address Before a Joint Session of the
Congress on the United States Response to the Terrorist Attacks of September 11
(Sept. 20, 2001), 2 Pub. Papers of Pres. George W. Bush 1140, 1142 (2001). The
NSA activities are an indispensable aspect of this defense of the Nation. By
targeting the international communications into and out of the United States of
persons reasonably believed to be linked to al Qaeda, these activities provide the
United States with an early warning system to help avert the next attack. For the
following reasons, the NSA activities are lawful and consistent with civil liberties.
The NSA activities are supported by the President’s well-recognized inherent
constitutional authority as Commander in Chief and sole organ for the Nation in
foreign affairs to conduct warrantless surveillance of enemy forces for intelligence
purposes to detect and disrupt armed attacks on the United States. The President
has the chief responsibility under the Constitution to protect America from attack,
and the Constitution gives the President the authority necessary to fulfill that
solemn responsibility. The President has made clear that he will exercise all

*
Editor’s Note: For purposes of publication, some of the citations in this White Paper (primarily
the internet citations) have been updated from the version sent to Congress. A version of the original is
available in H.R. Rep. No. 109-384, at 6–54 (Mar. 7, 2006).

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 Legal Authorities Supporting the Activities of the National Security Agency

authority available to him, consistent with the Constitution, to protect the people
of the United States.
In the specific context of the current armed conflict with al Qaeda and related
terrorist organizations, Congress by statute has confirmed and supplemented the
President’s recognized authority under Article II of the Constitution to conduct
such warrantless surveillance to prevent further catastrophic attacks on the
homeland. In its first legislative response to the terrorist attacks of September
11th, Congress authorized the President to “use all necessary and appropriate force
against those nations, organizations, or persons he determines planned, authorized,
committed, or aided the terrorist attacks” of September 11th in order to prevent
“any future acts of international terrorism against the United States.” Authoriza-
tion for Use of Military Force, Pub. L. No. 107-40, § 2(a), 115 Stat. 224, 224
(Sept. 18, 2001) (reported as a note to 50 U.S.C. § 1541) (“AUMF”). History
conclusively demonstrates that warrantless communications intelligence targeted
at the enemy in time of armed conflict is a traditional and fundamental incident of
the use of military force authorized by the AUMF. The Supreme Court’s interpre-
tation of the AUMF in Hamdi v. Rumsfeld, 542 U.S. 507 (2004), confirms that
Congress in the AUMF gave its express approval to the military conflict against al
Qaeda and its allies and thereby to the President’s use of all traditional and
accepted incidents of force in this current military conflict—including warrantless
electronic surveillance to intercept enemy communications both at home and
abroad. This understanding of the AUMF demonstrates Congress’s support for the
President’s authority to protect the Nation and, at the same time, adheres to Justice
O’Connor’s admonition that “a state of war is not a blank check for the President,”
Hamdi, 542 U.S. at 536 (plurality opinion), particularly in view of the narrow
scope of the NSA activities.
The AUMF places the President at the zenith of his powers in authorizing the
NSA activities. Under the tripartite framework set forth by Justice Jackson in
Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 635–38 (1952) (Jackson,
J., concurring), presidential authority is analyzed to determine whether the
President is acting in accordance with congressional authorization (category I),
whether he acts in the absence of a grant or denial of authority by Congress
(category II), or whether he uses his own authority under the Constitution to take
actions incompatible with congressional measures (category III). Because of the
broad authorization provided in the AUMF, the President’s action here falls within
category I of Justice Jackson’s framework. Accordingly, the President’s power in
authorizing the NSA activities is at its height because he acted “pursuant to an
express or implied authorization of Congress,” and his power “includes all that he
possesses in his own right plus all that Congress can delegate.” Id. at 635.
The NSA activities are consistent with the preexisting statutory framework gen-
erally applicable to the interception of communications in the United States—the
Foreign Intelligence Surveillance Act (“FISA”), as amended, 50 U.S.C. §§ 1801–

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1862 (2000 & Supp. II 2002), and relevant related provisions in chapter 119 of title
18. 1 Although FISA generally requires judicial approval of electronic surveillance,
FISA also contemplates that Congress may authorize such surveillance by a statute
other than FISA. See 50 U.S.C. § 1809(a) (prohibiting any person from intentionally
“engag[ing] . . . in electronic surveillance under color of law except as authorized by
statute”). The AUMF, as construed by the Supreme Court in Hamdi and as con-
firmed by the history and tradition of armed conflict, is just such a statute. Accord-
ingly, electronic surveillance conducted by the President pursuant to the AUMF,
including the NSA activities, is fully consistent with FISA and falls within category I
of Justice Jackson’s framework.
Even if there were ambiguity about whether FISA, read together with the
AUMF, permits the President to authorize the NSA activities, the canon of
constitutional avoidance requires reading these statutes in harmony to overcome
any restrictions in FISA and Title III, at least as they might otherwise apply to the
congressionally-authorized armed conflict with al Qaeda. Indeed, were FISA and
Title III interpreted to impede the President’s ability to use the traditional tool of
electronic surveillance to detect and prevent future attacks by a declared enemy
that has already struck at the homeland and is engaged in ongoing operations
against the United States, the constitutionality of FISA, as applied to that situation,
would be called into very serious doubt. In fact, if this difficult constitutional
question had to be addressed, FISA would be unconstitutional as applied to this
narrow context. Importantly, the FISA Court of Review itself recognized just three
years ago that the President retains constitutional authority to conduct foreign
surveillance apart from the FISA framework, and the President is certainly
entitled, at a minimum, to rely on that judicial interpretation of the Constitution
and FISA.
Finally, the NSA activities fully comply with the requirements of the Fourth
Amendment. The interception of communications described by the President falls
within a well-established exception to the warrant requirement and satisfies the
Fourth Amendment’s fundamental requirement of reasonableness. The NSA
activities are thus constitutionally permissible and fully protective of civil liberties.

II. Background

A. The Attacks of September 11, 2001

On September 11, 2001, the al Qaeda terrorist network launched a set of coor-
dinated attacks along the East Coast of the United States. Four commercial
jetliners, each carefully selected to be fully loaded with fuel for a transcontinental

1
Chapter 119 of title 18, which was enacted by title III of the Omnibus Crime Control and Safe
Streets Act of 1968, as amended, 18 U.S.C. §§ 2510–2521 (2000 & Supp. IV 2005), is often referred to
as “Title III.”

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 Legal Authorities Supporting the Activities of the National Security Agency

flight, were hijacked by al Qaeda operatives. Two of the jetliners were targeted at
the Nation’s financial center in New York and were deliberately flown into the
Twin Towers of the World Trade Center. The third was targeted at the headquar-
ters of the Nation’s Armed Forces, the Pentagon. The fourth was apparently
headed toward Washington, D.C., when passengers struggled with the hijackers
and the plane crashed in Shanksville, Pennsylvania. The intended target of this
fourth jetliner was evidently the White House or the Capitol, strongly suggesting
that its intended mission was to strike a decapitation blow on the Government of
the United States—to kill the President, the Vice President, or members of
Congress. The attacks of September 11th resulted in approximately 3,000 deaths—
the highest single-day death toll from hostile foreign attacks in the Nation’s
history. These attacks shut down air travel in the United States, disrupted the
Nation’s financial markets and government operations, and caused billions of
dollars in damage to the economy.
On September 14, 2001, the President declared a national emergency “by rea-
son of the terrorist attacks at the World Trade Center, New York, New York, and
the Pentagon, and the continuing and immediate threat of further attacks on the
United States.” Proclamation No. 7463, 66 Fed. Reg. 48,199 (Sept. 14, 2001). The
same day, Congress passed a joint resolution authorizing the President “to use all
necessary and appropriate force against those nations, organizations, or persons he
determines planned, authorized, committed, or aided the terrorist attacks” of
September 11th, which the President signed on September 18th. AUMF § 2(a).
Congress also expressly acknowledged that the attacks rendered it “necessary and
appropriate” for the United States to exercise its right “to protect United States
citizens both at home and abroad,” and in particular recognized that “the President
has authority under the Constitution to take action to deter and prevent acts of
international terrorism against the United States.” Id. pmbl. Congress emphasized
that the attacks “continue to pose an unusual and extraordinary threat to the
national security and foreign policy of the United States.” Id. The United States
also launched a large-scale military response, both at home and abroad. In the
United States, combat air patrols were immediately established over major
metropolitan areas and were maintained 24 hours a day until April 2002. The
United States also immediately began plans for a military response directed at al
Qaeda’s base of operations in Afghanistan. Acting under his constitutional
authority as Commander in Chief, and with the support of Congress, the President
dispatched forces to Afghanistan and, with the assistance of the Northern Alliance,
toppled the Taliban regime.
As the President made explicit in his Military Order of November 13, 2001,
authorizing the use of military commissions to try terrorists, the attacks of
September 11th “created a state of armed conflict.” Military Order § 1(a), 66 Fed.
Reg. 57,833 (Nov. 13, 2001). Indeed, shortly after the attacks, NATO—for the
first time in its 46-year history—invoked article 5 of the North Atlantic Treaty,
which provides that an “armed attack against one or more of [the parties] shall be

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considered an attack against them all.” North Atlantic Treaty art. 5, Apr. 4, 1949,
63 Stat. 2241, 2244, 34 U.N.T.S. 243, 246; see also Statement by NATO Secretary
General Lord Robertson (Oct. 2, 2001) (“it has now been determined that the
attack against the United States on 11 September was directed from abroad and
shall therefore be regarded as an action covered by Article 5 of the Washington
Treaty”) (available at http://www.nato.int/docu/speech/2001/s011002a.htm, last
visited Aug. 12, 2014). The President also determined in his Military Order that al
Qaeda and related terrorists organizations “possess both the capability and the
intention to undertake further terrorist attacks against the United States that, if not
detected and prevented, will cause mass deaths, mass injuries, and massive
destruction of property, and may place at risk the continuity of the operations of
the United States Government,” and concluded that “an extraordinary emergency
exists for national defense purposes.” Military Order § 1(c), (g), 66 Fed. Reg. at
57,833–34.

B. The NSA Activities

Against this unfolding background of events in the fall of 2001, there was
substantial concern that al Qaeda and its allies were preparing to carry out
another attack within the United States. Al Qaeda had demonstrated its ability to
introduce agents into the United States undetected and to perpetrate devastating
attacks, and it was suspected that additional agents were likely already in
position within the Nation’s borders. As the President has explained, unlike a
conventional enemy, al Qaeda has infiltrated “our cities and communities and
communicated from here in America to plot and plan with bin Laden’s lieuten-
ants in Afghanistan, Pakistan and elsewhere.” The President’s News Conference,
41 Weekly Comp. Pres. Doc. 1885, 1885 (Dec. 19, 2005). To this day, finding al
Qaeda sleeper agents in the United States remains one of the paramount
concerns in the War on Terror. As the President has explained, “[t]he terrorists
want to strike America again, and they hope to inflict even more damage than
they did on September the 11th.” Id. at 1886.
The President has acknowledged that, to counter this threat, he has authorized
the NSA to intercept international communications into and out of the United
States of persons linked to al Qaeda or related terrorist organizations. The same
day, the Attorney General elaborated and explained that in order to intercept a
communication, there must be “a reasonable basis to conclude that one party to the
communication is a member of al Qaeda, affiliated with al Qaeda, or a member of
an organization affiliated with al Qaeda.” Press Briefing by Attorney General
Alberto Gonzales and General Michael Hayden, Principal Deputy Director for
National Intelligence (Dec. 19, 2005) (statement of Attorney General Gonzales)
(available at http://georgewbush-whitehouse.archives.gov/news/releases/2005/12/
20051219-1.html, last visited Aug. 12, 2014). The purpose of these intercepts is to
establish an early warning system to detect and prevent another catastrophic

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terrorist attack on the United States. The President has stated that the NSA
activities “ha[ve] been effective in disrupting the enemy, while safeguarding our
civil liberties.” President’s News Conference, 41 Weekly Comp. Pres. Doc. at
1885.
The President has explained that the NSA activities are “critical” to the national
security of the United States. Id. at 1886. Confronting al Qaeda “is not simply a
matter of [domestic] law enforcement”—we must defend the country against an
enemy that declared war against the United States. Id. at 1885. To “effectively
detect enemies hiding in our midst and prevent them from striking us again . . . we
must be able to act fast and to detect conversations [made by individuals linked to
al Qaeda] so we can prevent new attacks.” Id. The President pointed out that “a 2-
minute phone conversation between somebody linked to al Qaeda here and an
operative overseas could lead directly to the loss of thousands of lives.” Id. The
NSA activities are intended to help “connect the dots” between potential terrorists.
Id. In addition, the Nation is facing “a different era, a different war . . . people are
changing phone numbers . . . and they’re moving quick.” Id. at 1891. As the
President explained, the NSA activities “enable[] us to move faster and quicker.
And that’s important. We’ve got to be fast on our feet, quick to detect and
prevent.” Id. at 1887. “This is an enemy which is quick, and it’s lethal. And
sometimes we have to move very, very quickly.” Id. at 1889. FISA, by contrast, is
better suited “for long-term monitoring.” Id. at 1887.
As the President has explained, the NSA activities are “carefully reviewed
approximately every 45 days to ensure [that they are] being used properly.” Id. at
1885. These activities are reviewed for legality by the Department of Justice and
are monitored by the General Counsel and Inspector General of the NSA to ensure
that civil liberties are being protected. Id. at 1891. Leaders in Congress from both
parties have been briefed more than a dozen times on the NSA activities. Id. at
1889.

C. The Continuing Threat Posed by Al Qaeda

Before the September 11th attacks, al Qaeda had promised to attack the United
States. In 1998, Osama bin Laden declared a “religious” war against the United
States and urged that it was the moral obligation of all Muslims to kill U.S.
civilians and military personnel. See Osama bin Laden, Ayman al-Zawahiri, et al.,
Fatwah Urging Jihad Against Americans, published in al-Quds al-Arabi (Feb. 23,
1998) (“to kill the Americans and their allies—civilians and military—is an
individual duty for every Muslim who can do it in any country in which it is
possible to do it, in order to liberate the al-Aqsa Mosque and the holy mosque
from their grip, and in order for their armies to move out of all the lands of Islam,
defeated and unable to threaten any Muslim”) (translation available at http://www.
fas.org/irp/world/para/docs/980223-fatwa.htm, last visited Aug. 12, 2014). Al
Qaeda carried out those threats with a vengeance; they attacked the U.S.S. Cole in

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Yemen, the United States Embassy in Nairobi, and finally the United States itself
in the September 11th attacks.
It is clear that al Qaeda is not content with the damage it wrought on September
11th. As recently as December 7, 2005, Ayman al-Zawahiri professed that al
Qaeda “is spreading, growing, and becoming stronger,” and that al Qaeda is
“waging a great historic battle in Iraq, Afghanistan, Palestine, and even in the
Crusaders’ own homes.” Ayman al-Zawahiri, videotape released on Al-Jazeera
television network (Dec. 7, 2005). Indeed, since September 11th, al Qaeda leaders
have repeatedly promised to deliver another, even more devastating attack on
America. See, e.g., Osama bin Laden, videotape released on Al-Jazeera television
network (Oct. 24, 2004) (warning United States citizens of further attacks and
asserting that “your security is in your own hands”); Osama bin Laden, videotape
released on Al-Jazeera television network (Oct. 18, 2003) (“We, God willing, will
continue to fight you and will continue martyrdom operations inside and outside
the United States”); Ayman Al-Zawahiri, videotape released on the Al-Jazeera
television network (Oct. 9, 2002) (“I promise you [addressing the ‘citizens of the
United States’] that the Islamic youth are preparing for you what will fill your
hearts with horror”). Given that al Qaeda’s leaders have repeatedly made good on
their threats and that al Qaeda has demonstrated its ability to insert foreign agents
into the United States to execute attacks, it is clear that the threat continues.
Indeed, since September 11th, al Qaeda has staged several large-scale attacks
around the world, including in Indonesia, Madrid, and London, killing hundreds of
innocent people.

III. Analysis

A. The President Has Inherent Constitutional Authority To Order
Warrantless Foreign Intelligence Surveillance

As Congress expressly recognized in the AUMF, “the President has authority
under the Constitution to take action to deter and prevent acts of international
terrorism against the United States,” AUMF pmbl., especially in the context of the
current conflict. Article II of the Constitution vests in the President all executive
power of the United States, including the power to act as Commander in Chief of
the Armed Forces, U.S. Const. art. II, § 2, and authority over the conduct of the
Nation’s foreign affairs. As the Supreme Court has explained, “[t]he President is
the sole organ of the nation in its external relations, and its sole representative with
foreign nations.” United States v. Curtiss-Wright Exp. Corp., 299 U.S. 304, 319
(1936) (internal quotation marks and citations omitted). In this way, the Constitu-
tion grants the President inherent power to protect the Nation from foreign attack,
see, e.g., The Prize Cases, 67 U.S. (2 Black) 635, 668 (1863), and to protect
national security information, see, e.g., Dep’t of Navy v. Egan, 484 U.S. 518, 527
(1988).

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To carry out these responsibilities, the President must have authority to gather
information necessary for the execution of his office. The Founders, after all,
intended the federal government to be clothed with all authority necessary to
protect the Nation. See, e.g., The Federalist No. 23, at 147 (Alexander Hamilton)
(Jacob E. Cooke ed. 1961) (explaining that the federal government will be
“cloathed with all the powers requisite to the complete execution of its trust”); id.
No. 41, at 269 (James Madison) (“Security against foreign danger is one of the
primitive objects of civil society . . . . The powers requisite for attaining it must be
effectually confided to the federal councils.”). Because of the structural advantages
of the Executive Branch, the Founders also intended that the President would have
the primary responsibility and necessary authority as Commander in Chief and
Chief Executive to protect the Nation and to conduct the Nation’s foreign affairs.
See, e.g., The Federalist No. 70, at 471–72 (Alexander Hamilton); see also
Johnson v. Eisentrager, 339 U.S. 763, 788 (1950) (“this [constitutional] grant of
war power includes all that is necessary and proper for carrying these powers into
execution”) (citation omitted). Thus, it has been long recognized that the President
has the authority to use secretive means to collect intelligence necessary for the
conduct of foreign affairs and military campaigns. See, e.g., Chi. & S. Air Lines v.
Waterman S.S. Corp., 333 U.S. 103, 111 (1948) (“The President, both as Com-
mander-in-Chief and as the Nation’s organ for foreign affairs, has available
intelligence services whose reports are not and ought not to be published to the
world.”); Curtiss-Wright, 299 U.S. at 320 (“He has his confidential sources of
information. He has his agents in the form of diplomatic, consular and other
officials.”); Totten v. United States, 92 U.S. 105, 106 (1876) (President “was
undoubtedly authorized during the war, as commander-in-chief . . . to employ
secret agents to enter the rebel lines and obtain information respecting the strength,
resources, and movements of the enemy”).
In reliance on these principles, a consistent understanding has developed that
the President has inherent constitutional authority to conduct warrantless searches
and surveillance within the United States for foreign intelligence purposes.
Wiretaps for such purposes thus have been authorized by Presidents at least since
the administration of Franklin Roosevelt in 1940. See, e.g., United States v. U.S.
Dist. Ct., 444 F.2d 651, 669–71 (6th Cir. 1971) (reproducing as an appendix
memoranda from Presidents Roosevelt, Truman, and Johnson). In a memorandum
to Attorney General Jackson, President Roosevelt wrote on May 21, 1940:

You are, therefore, authorized and directed in such cases as you may
approve, after investigation of the need in each case, to authorize the
necessary investigation agents that they are at liberty to secure in-
formation by listening devices directed to the conversation or other
communications of persons suspected of subversive activities against
the Government of the United States, including suspected spies. You

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are requested furthermore to limit these investigations so conducted
to a minimum and limit them insofar as possible to aliens.

Id. at 670 (app. A). President Truman approved a memorandum drafted by
Attorney General Tom Clark in which the Attorney General advised that “it is as
necessary as it was in 1940 to take the investigative measures” authorized by
President Roosevelt to conduct electronic surveillance “in cases vitally affecting
the domestic security.” Id. Indeed, while FISA was being debated during the
Carter Administration, Attorney General Griffin Bell testified that “the current bill
recognizes no inherent power of the President to conduct electronic surveillance,
and I want to interpolate here to say that this does not take away the power [of] the
President under the Constitution.” Foreign Intelligence Electronic Surveillance
Act of 1978: Hearings on H.R. 5764, H.R. 9745, H.R. 7308, and H.R. 5632 Before
the Subcomm. on Legislation of the H. Comm. on Intelligence, 95th Cong. 15
(1978) (emphasis added); see also Katz v. United States, 389 U.S. 347, 363 (1967)
(White, J., concurring) (“Wiretapping to protect the security of the Nation has
been authorized by successive Presidents.”); cf. Amending the Foreign Intelligence
Surveillance Act: Hearings Before the H. Permanent Select Comm. on Intelli-
gence, 103d Cong. 61 (1994) (statement of Deputy Attorney General Jamie S.
Gorelick) (“the Department of Justice believes, and the case law supports, that the
President has inherent authority to conduct warrantless physical searches for
foreign intelligence purposes”).
The courts uniformly have approved this longstanding Executive Branch prac-
tice. Indeed, every federal appellate court to rule on the question has concluded
that, even in peacetime, the President has inherent constitutional authority,
consistent with the Fourth Amendment, to conduct searches for foreign intelli-
gence purposes without securing a judicial warrant. See In re Sealed Case, 310
F.3d 717, 742 (FISA Ct. Rev. 2002) (“[A]ll the other courts to have decided the
issue [have] held that the President did have inherent authority to conduct
warrantless searches to obtain foreign intelligence information . . . . We take for
granted that the President does have that authority and, assuming that is so, FISA
could not encroach on the President’s constitutional power.”) (emphasis added);
accord, e.g., United States v. Truong Dinh Hung, 629 F.2d 908 (4th Cir. 1980);
United States v. Butenko, 494 F.2d 593 (3d Cir. 1974) (en banc); United States v.
Brown, 484 F.2d 418 (5th Cir. 1973). But cf. Zweibon v. Mitchell, 516 F.2d 594
(D.C. Cir. 1975) (en banc) (dictum in plurality opinion suggesting that a warrant
would be required even in a foreign intelligence investigation).
In United States v. United States District Court, 407 U.S. 297 (1972) (the
“Keith” case), the Supreme Court concluded that the Fourth Amendment’s warrant
requirement applies to investigations of wholly domestic threats to security—such
as domestic political violence and other crimes. But the Court in the Keith case
made clear that it was not addressing the President’s authority to conduct foreign
intelligence surveillance without a warrant and that it was expressly reserving that

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question: “[T]he instant case requires no judgment on the scope of the President’s
surveillance power with respect to the activities of foreign powers, within or
without this country.” Id. at 308; see also id. at 321–22 & n.20 (“We have not
addressed, and express no opinion as to, the issues which may be involved with
respect to activities of foreign powers or their agents.”). That Keith does not apply
in the context of protecting against a foreign attack has been confirmed by the
lower courts. After Keith, each of the three courts of appeals that have squarely
considered the question have concluded—expressly taking the Supreme Court’s
decision into account—that the President has inherent authority to conduct
warrantless surveillance in the foreign intelligence context. See, e.g., Truong Dinh
Hung, 629 F.2d at 913–14; Butenko, 494 F.2d at 603; Brown, 484 F.2d 425–26.
From a constitutional standpoint, foreign intelligence surveillance such as the
NSA activities differs fundamentally from the domestic security surveillance at
issue in Keith. As the Fourth Circuit observed, the President has uniquely strong
constitutional powers in matters pertaining to foreign affairs and national security.
“Perhaps most crucially, the executive branch not only has superior expertise in
the area of foreign intelligence, it is also constitutionally designated as the pre-
eminent authority in foreign affairs.” Truong, 629 F.2d at 914; see id. at 913
(noting that “the needs of the executive are so compelling in the area of foreign
intelligence, unlike the area of domestic security, that a uniform warrant require-
ment would . . . unduly frustrate the President in carrying out his foreign affairs
responsibilities”); cf. Haig v. Agee, 453 U.S. 280, 292 (1981) (“Matters intimately
related to foreign policy and national security are rarely proper subjects for judicial
intervention.”). 2
The present circumstances that support recognition of the President’s inherent
constitutional authority to conduct the NSA activities are considerably stronger
than were the circumstances at issue in the earlier courts of appeals cases that
recognized this power. All of the cases described above addressed inherent
executive authority under the foreign affairs power to conduct surveillance in a
peacetime context. The courts in these cases therefore had no occasion even to
consider the fundamental authority of the President, as Commander in Chief, to
gather intelligence in the context of an ongoing armed conflict in which the United

2
Keith made clear that one of the significant concerns driving the Court’s conclusion in the domes-
tic security context was the inevitable connection between perceived threats to domestic security and
political dissent. As the Court explained: “Fourth Amendment protections become the more necessary
when the targets of official surveillance may be those suspected of unorthodoxy in their political
beliefs. The danger to political dissent is acute where the Government attempts to act under so vague a
concept as the power to protect ‘domestic security.’” Keith, 407 U.S. at 314; see also id. at 320
(“Security surveillances are especially sensitive because of the inherent vagueness of the domestic
security concept, the necessarily broad and continuing nature of intelligence gathering, and the
temptation to utilize such surveillances to oversee political dissent.”). Surveillance of domestic groups
raises a First Amendment concern that generally is not present when the subjects of the surveillance are
foreign powers or their agents.

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States already had suffered massive civilian casualties and in which the intelli-
gence gathering efforts at issue were specifically designed to thwart further armed
attacks. Indeed, intelligence gathering is particularly important in the current
conflict, in which the enemy attacks largely through clandestine activities and
which, as Congress recognized, “pose[s] an unusual and extraordinary threat,”
AUMF pmbl.
Among the President’s most basic constitutional duties is the duty to protect the
Nation from armed attack. The Constitution gives him all necessary authority to
fulfill that responsibility. The courts thus have long acknowledged the President’s
inherent authority to take action to protect Americans abroad, see, e.g., Durand v.
Hollins, 8 F. Cas. 111, 112 (C.C.S.D.N.Y. 1860) (No. 4186), and to protect the
Nation from attack, see, e.g., Prize Cases, 67 U.S. at 668. See generally Ex parte
Quirin, 317 U.S. 1, 28 (1942) (recognizing that the President has authority under
the Constitution “to direct the performance of those functions which may constitu-
tionally be performed by the military arm of the nation in time of war,” including
“important incident[s] to the conduct of war,” such as “the adoption of measures
by the military command . . . to repel and defeat the enemy”). As the Supreme
Court emphasized in the Prize Cases, if the Nation is invaded, the President is
“bound to resist force by force”; “[h]e must determine what degree of force the
crisis demands” and need not await congressional sanction to do so. 67 U.S. at
670; see also Campbell v. Clinton, 203 F.3d 19, 27 (D.C. Cir. 2000) (Silberman,
J., concurring) (“[T]he Prize Cases . . . stand for the proposition that the President
has independent authority to repel aggressive acts by third parties even without
specific congressional authorization, and courts may not review the level of force
selected.”); id. at 40 (Tatel, J., concurring) (“[T]he President, as commander in
chief, possesses emergency authority to use military force to defend the nation
from attack without obtaining prior congressional approval.”). Indeed, “in virtue of
his rank as head of the forces, [the President] has certain powers and duties with
which Congress cannot interfere.” Training of British Flying Students in the
United States, 40 Op. Att’y Gen. 58, 61 (1941) (Attorney General Robert H.
Jackson) (internal quotation marks omitted). In exercising his constitutional
powers, the President has wide discretion, consistent with the Constitution, over
the methods of gathering intelligence about the Nation’s enemies in a time of
armed conflict.

B. The AUMF Confirms and Supplements the President’s
Inherent Power to Use Warrantless Surveillance
Against the Enemy in the Current Armed Conflict

In the Authorization for Use of Military Force enacted in the wake of Septem-
ber 11th, Congress confirms and supplements the President’s constitutional
authority to protect the Nation, including through electronic surveillance, in the
context of the current post-September 11th armed conflict with al Qaeda and its

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 Legal Authorities Supporting the Activities of the National Security Agency

allies. The broad language of the AUMF affords the President, at a minimum,
discretion to employ the traditional incidents of the use of military force. The
history of the President’s use of warrantless surveillance during armed conflicts
demonstrates that the NSA surveillance described by the President is a fundamen-
tal incident of the use of military force that is necessarily included in the AUMF.

1. The Text and Purpose of the AUMF Authorize the NSA Activities

On September 14, 2001, in its first legislative response to the attacks of Sep-
tember 11th, Congress gave its express approval to the President’s military
campaign against al Qaeda and, in the process, confirmed the well-accepted
understanding of the President’s Article II powers. AUMF § 2(a). 3 In the preamble
to the AUMF, Congress stated that “the President has authority under the Constitu-
tion to take action to deter and prevent acts of international terrorism against the
United States,” AUMF pmbl., and thereby acknowledged the President’s inherent
constitutional authority to defend the United States. This clause “constitutes an
extraordinarily sweeping recognition of independent presidential constitutional
power to employ the war power to combat terrorism.” Michael Stokes Paulsen,
Youngstown Goes to War, 19 Const. Comment. 215, 252 (2002). This striking
recognition of presidential authority cannot be discounted as the product of
excitement in the immediate aftermath of September 11th, for the same terms were
repeated by Congress more than a year later in the Authorization for Use of
Military Force Against Iraq Resolution of 2002. Pub. L. No. 107-243, pmbl., 116
Stat. 1498, 1500 (Oct. 16, 2002) (“the President has authority under the Constitu-
tion to take action in order to deter and prevent acts of international terrorism
against the United States”). In the context of the conflict with al Qaeda and related
terrorist organizations, therefore, Congress has acknowledged a broad executive
authority to “deter and prevent” further attacks against the United States.
The AUMF passed by Congress on September 14, 2001, does not lend itself to
a narrow reading. Its expansive language authorizes the President “to use all
necessary and appropriate force against those nations, organizations, or persons
he determines planned, authorized, committed, or aided the terrorist attacks that
occurred on September 11, 2001.” AUMF § 2(a) (emphases added). In the field of
foreign affairs, and particularly that of war powers and national security, congres-
sional enactments are to be broadly construed where they indicate support for
authority long asserted and exercised by the Executive Branch. See, e.g., Haig v.
Agee, 453 U.S. 280, 293–303 (1981); United States ex rel. Knauff v. Shaughnessy,
338 U.S. 537, 543–45 (1950); cf. Loving v. United States, 517 U.S. 748, 772
(1996) (noting that the usual “limitations on delegation [of congressional powers]

3
America’s military response began before the attacks of September 11th had been completed. See
The 9/11 Commission Report 20 (2004). Combat air patrols were established and authorized “to engage
inbound aircraft if they could verify that the aircraft was hijacked.” Id. at 42.

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 Opinions of the Office of Legal Counsel in Volume 30

do not apply” to authorizations linked to the Commander in Chief power); Dames
& Moore v. Regan, 453 U.S. 654, 678–82 (1981) (even where there is no express
statutory authorization for executive action, legislation in related field may be
construed to indicate congressional acquiescence in that action). Although
Congress’s war powers under Article I, Section 8 of the Constitution empower
Congress to legislate regarding the raising, regulation, and material support of the
Armed Forces and related matters, rather than the prosecution of military cam-
paigns, the AUMF indicates Congress’s endorsement of the President’s use of his
constitutional war powers. This authorization transforms the struggle against al
Qaeda and related terrorist organizations from what Justice Jackson called “a zone
of twilight,” in which the President and the Congress may have concurrent powers
whose “distribution is uncertain,” Youngstown Sheet & Tube Co. v. Sawyer, 343
U.S. 579, 637 (1952) (Jackson, J., concurring), into a situation in which the
President’s authority is at is maximum because “it includes all that he possesses in
his own right plus all that Congress can delegate,” id. at 635. With regard to these
fundamental tools of warfare—and, as demonstrated below, warrantless electronic
surveillance against the declared enemy is one such tool—the AUMF places the
President’s authority at its zenith under Youngstown.
It is also clear that the AUMF confirms and supports the President’s use of
those traditional incidents of military force against the enemy, wherever they may
be—on United States soil or abroad. The nature of the September 11th attacks—
launched on United States soil by foreign agents secreted in the United States—
necessitates such authority, and the text of the AUMF confirms it. The operative
terms of the AUMF state that the President is authorized to use force “in order to
prevent any future acts of international terrorism against the United States,” id., an
objective which, given the recent attacks within the Nation’s borders and the
continuing use of air defense throughout the country at the time Congress acted,
undoubtedly contemplated the possibility of military action within the United
States. The preamble, moreover, recites that the United States should exercise its
rights “to protect United States citizens both at home and abroad.” Id. pmbl.
(emphasis added). To take action against those linked to the September 11th
attacks involves taking action against individuals within the United States. The
United States had been attacked on its own soil—not by aircraft launched from
carriers several hundred miles away, but by enemy agents who had resided in the
United States for months. A crucial responsibility of the President—charged by
the AUMF and the Constitution—was and is to identify and attack those enemies,
especially if they were in the United States, ready to strike against the Nation.
The text of the AUMF demonstrates in an additional way that Congress author-
ized the President to conduct warrantless electronic surveillance against the
enemy. The terms of the AUMF not only authorized the President to “use all
necessary and appropriate force” against those responsible for the September 11th
attacks; it also authorized the President to “determine[]” the persons or groups
responsible for those attacks and to take all actions necessary to prevent further

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 Legal Authorities Supporting the Activities of the National Security Agency

attacks. AUMF § 2(a) (“the President is authorized to use all necessary and
appropriate force against those nations, organizations, or persons he determines
planned, authorized, committed, or aided the terrorist attacks that occurred on
September 11th, 2001, or harbored such organizations or persons”) (emphasis
added). Of vital importance to the use of force against the enemy is locating the
enemy and identifying its plans of attack. And of vital importance to identifying
the enemy and detecting possible future plots was the authority to intercept
communications to or from the United States of persons with links to al Qaeda or
related terrorist organizations. Given that the agents who carried out the initial
attacks resided in the United States and had successfully blended into American
society and disguised their identities and intentions until they were ready to strike,
the necessity of using the most effective intelligence gathering tools against such
an enemy, including electronic surveillance, was patent. Indeed, Congress
recognized that the enemy in this conflict poses an “unusual and extraordinary
threat.” AUMF pmbl.
The Supreme Court’s interpretation of the scope of the AUMF in Hamdi v.
Rumsfeld, 542 U.S. 507 (2004), strongly supports this reading of the AUMF. In
Hamdi, five members of the Court found that the AUMF authorized the detention
of an American within the United States, notwithstanding a statute that prohibits
the detention of U.S. citizens “except pursuant to an Act of Congress,” 18 U.S.C.
§ 4001(a). See Hamdi, 542 U.S. at 519 (plurality opinion); id. at 587 (Thomas, J.,
dissenting). Drawing on historical materials and “longstanding law-of-war
principles,” id. at 518–21, a plurality of the Court concluded that detention of
combatants who fought against the United States as part of an organization
“known to have supported” al Qaeda “is so fundamental and accepted an incident
to war as to be an exercise of the ‘necessary and appropriate force’ Congress has
authorized the President to use.” Id. at 518; see also id. at 587 (Thomas, J.,
dissenting) (agreeing with the plurality that the joint resolution authorized the
President to “detain those arrayed against our troops”); accord Quirin, 317 U.S. at
26–29, 38 (recognizing the President’s authority to capture and try agents of the
enemy in the United States even if they had never “entered the theatre or zone of
active military operations”). Thus, even though the AUMF does not say anything
expressly about detention, the Court nevertheless found that it satisfied section
4001(a)’s requirement that detention be congressionally authorized.
The conclusion of five Justices in Hamdi that the AUMF incorporates funda-
mental “incidents” of the use of military force makes clear that the absence of any
specific reference to signals intelligence activities in the resolution is immaterial.
See id. at 519 (“[I]t is of no moment that the AUMF does not use specific language
of detention.”) (plurality opinion). Indeed, given the circumstances in which the
AUMF was adopted, it is hardly surprising that Congress chose to speak about the
President’s authority in general terms. The purpose of the AUMF was for Con-
gress to sanction and support the military response to the devastating terrorist
attacks that had occurred just three days earlier. Congress evidently thought it

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 Opinions of the Office of Legal Counsel in Volume 30

neither necessary nor appropriate to attempt to catalog every specific aspect of the
use of the forces it was authorizing and every potential preexisting statutory
limitation on the Executive Branch. Rather than engage in that difficult and
impractical exercise, Congress authorized the President, in general but intentional-
ly broad terms, to use the traditional and fundamental incidents of war and to
determine how best to identify and engage the enemy in the current armed
conflict. Congress’s judgment to proceed in this manner was unassailable, for, as
the Supreme Court has recognized, even in normal times involving no major
national security crisis, “Congress cannot anticipate and legislate with regard to
every possible action the President may find it necessary to take.” Dames &
Moore, 453 U.S. at 678. Indeed, Congress often has enacted authorizations to use
military force using general authorizing language that does not purport to cata-
logue in detail the specific powers the President may employ. The need for
Congress to speak broadly in recognizing and augmenting the President’s core
constitutional powers over foreign affairs and military campaigns is of course
significantly heightened in times of national emergency. See Zemel v. Rusk, 381
U.S. 1, 17 (1965) (“[B]ecause of the changeable and explosive nature of contem-
porary international relations . . . Congress—in giving the Executive authority
over matters of foreign affairs—must of necessity paint with a brush broader than
that it customarily wields in domestic areas.”).
Hamdi thus establishes the proposition that the AUMF “clearly and unmistaka-
bly” authorizes the President to take actions against al Qaeda and related organiza-
tions that amount to “fundamental incident[s] of waging war.” 542 U.S. at 519
(plurality opinion); see also id. at 587 (Thomas, J., dissenting). In other words,
“[t]he clear inference is that the AUMF authorizes what the laws of war permit.”
Curtis A. Bradley & Jack L. Goldsmith, Congressional Authorization and the War
on Terrorism, 118 Harv. L. Rev. 2048, 2092 (2005) (emphasis added). Congress is
presumed to be aware of the Supreme Court’s precedents. Indeed, Congress
recently enacted legislation in response to the Court’s decision in Rasul v. Bush,
542 U.S. 466 (2004)—which was issued the same day as the Hamdi decision—
removing habeas corpus jurisdiction over claims filed on behalf of confined enemy
combatants held at Guantanamo Bay. Congress, however, has not expressed any
disapproval of the Supreme Court’s commonsense and plain-meaning interpreta-
tion of the AUMF in Hamdi. 4

4
This understanding of the AUMF is consistent with Justice O’Connor’s admonition that “a state of
war is not a blank check for the President,” Hamdi, 542 U.S. at 536 (plurality opinion). In addition to
constituting a fundamental and accepted incident of the use of military force, the NSA activities are
consistent with the law of armed conflict principle that the use of force be necessary and proportional.
See Dieter Fleck, The Handbook of Humanitarian Law in Armed Conflicts 115 (1995). The NSA
activities are proportional because they are minimally invasive and narrow in scope, targeting only the
international communications of persons reasonably believed to be linked to al Qaeda, and are designed
to protect the Nation from a devastating attack.

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 Legal Authorities Supporting the Activities of the National Security Agency

2. Warrantless Electronic Surveillance Aimed at Intercepting
Enemy Communications Has Long Been Recognized as a
Fundamental Incident of the Use of Military Force

The history of warfare—including the consistent practice of Presidents since
the earliest days of the Republic—demonstrates that warrantless intelligence
surveillance against the enemy is a fundamental incident of the use of military
force, and this history confirms the statutory authority provided by the AUMF.
Electronic surveillance is a fundamental tool of war that must be included in any
natural reading of the AUMF’s authorization to use “all necessary and appropriate
force.”
As one author has explained:

It is essential in warfare for a belligerent to be as fully informed as
possible about the enemy—his strength, his weaknesses, measures
taken by him and measures contemplated by him. This applies not
only to military matters, but . . . anything which bears on and is ma-
terial to his ability to wage the war in which he is engaged. The laws
of war recognize and sanction this aspect of warfare.

Morris Greenspan, The Modern Law of Land Warfare 325 (1959) (emphases
added); see also Memorandum for Members of the House Permanent Select
Committee on Intelligence, from Jeffrey H. Smith, Re: Legal Authorities Regard-
ing Warrantless Surveillance of U.S. Persons at 6 (Jan. 3, 2006) (“Certainly, the
collection of intelligence is understood to be necessary to the execution of the
war.”). Similarly, article 24 of the Hague Regulations of 1907 expressly states that
“the employment of measures necessary for obtaining information about the
enemy and the country [is] considered permissible.” See also 2 L. Oppenheim,
International Law § 159 (7th ed. 1952) (“War cannot be waged without all kinds
of information, about the forces and the intentions of the enemy . . . . To obtain the
necessary information, it has always been considered lawful to employ
spies . . . .”); Joseph R. Baker & Henry G. Crocker, The Laws of Land Warfare
197 (1919) (“Every belligerent has a right . . . to discover the signals of the enemy
and . . . to seek to procure information regarding the enemy through the aid of
secret agents.”); cf. J.M. Spaight, War Rights on Land 205 (1911) (“[E]very nation
employs spies; were a nation so quixotic as to refrain from doing so, it might as
well sheathe its sword for ever. . . . Spies . . . are indispensably necessary to a
general; and, other things being equal, that commander will be victorious who has
the best secret service.”) (internal quotation marks omitted).
In accordance with these well-established principles, the Supreme Court has
consistently recognized the President’s authority to conduct intelligence activities.
See, e.g., Totten v. United States, 92 U.S. 105, 106 (1876) (recognizing President’s
authority to hire spies); Tenet v. Doe, 544 U.S. 1 (2005) (reaffirming Totten and

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counseling against judicial interference with such matters); see also Chicago & S.
Air Lines v. Waterman S.S. Corp., 333 U.S. 103, 111 (1948) (“The President, both
as Commander-in-Chief and as the Nation’s organ for foreign affairs, has available
intelligence services whose reports neither are not and ought not to be published to
the world.”); United States v. Curtiss-Wright Exp. Corp., 299 U.S. 304, 320 (1936)
(The President “has his confidential sources of information. He has his agents in
the form of diplomatic, consular, and other officials.”). Chief Justice John
Marshall even described the gathering of intelligence as a military duty. See Tatum
v. Laird, 444 F.2d 947, 952–53 (D.C. Cir. 1971) (“As Chief Justice John Marshall
said of Washington, ‘A general must be governed by his intelligence and must
regulate his measures by his information. It is his duty to obtain correct infor-
mation . . . . ’”) (quoting Foreword, U.S. Army Basic Field Manual, Vol. X, circa
1938), rev’d on other grounds, 408 U.S. 1 (1972).
The United States, furthermore, has a long history of wartime surveillance—a
history that can be traced to George Washington, who “was a master of military
espionage” and “made frequent and effective use of secret intelligence in the
second half of the eighteenth century.” Rhodri Jeffreys-Jones, Cloak and Dollar: A
History of American Secret Intelligence 11 (2002); see generally id. at 11–23
(recounting Washington’s use of intelligence); see also Haig v. Agee, 471 U.S.
159, 172 n.16 (1981) (quoting General Washington’s letter to an agent embarking
upon an intelligence mission in 1777: “The necessity of procuring good intelli-
gence, is apparent and need not be further urged.”). As President in 1790, Wash-
ington obtained from Congress a “secret fund” to deal with foreign dangers and to
be spent at his discretion. Jeffreys-Jones, Cloak and Dollar at 22. The fund, which
remained in use until the creation of the Central Intelligence Agency in the mid-
twentieth century and gained “longstanding acceptance within our constitutional
structure,” Halperin v. CIA, 629 F.2d 144, 158–59 (D.C. Cir. 1980), was used “for
all purposes to which a secret service fund should or could be applied for the
public benefit,” including “for persons sent publicly and secretly to search for
important information, political or commercial,” id. at 159 (quoting 7 Reg. Deb.
295 (Feb. 25, 1831) (statement of Senator John Forsyth)). See also Totten, 92 U.S.
at 107 (refusing to examine payments from this fund lest the publicity make a
“secret service” “impossible”).
The interception of communications, in particular, has long been accepted as a
fundamental method for conducting wartime surveillance. See, e.g., Greenspan,
Land Warfare at 326 (accepted and customary means for gathering intelligence
“include air reconnaissance and photography; ground reconnaissance; observation
of enemy positions; interception of enemy messages, wireless and other; examina-
tion of captured documents; . . . and interrogation of prisoners and civilian
inhabitants”) (emphasis added). Indeed, since its independence, the United States
has intercepted communications for wartime intelligence purposes and, if neces-
sary, has done so within its own borders. During the Revolutionary War, for
example, George Washington received and used to his advantage reports from

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 Legal Authorities Supporting the Activities of the National Security Agency

American intelligence agents on British military strength, British strategic
intentions, and British estimates of American strength. See Jeffreys-Jones, Cloak
and Dollar at 13. One source of Washington’s intelligence was intercepted British
mail. See Central Intelligence Agency, Intelligence in the War of Independence 31,
32 (1997). In fact, Washington himself proposed that one of his generals “contrive
a means of opening [British letters] without breaking the seals, take copies of the
contents, and then let them go on.” Id. at 32 (“From that point on, Washington was
privy to British intelligence pouches between New York and Canada.”); see
generally Final Report of the Select Committee to Study Governmental Operations
With Respect to Intelligence Activities (the “Church Committee”), S. Rep. No. 94-
755, bk. VI, at 9–17 (Apr. 23, 1976) (describing Washington’s intelligence activi–
ties).
More specifically, warrantless electronic surveillance of wartime communica-
tions has been conducted in the United States since electronic communications
have existed, i.e., since at least the Civil War, when “[t]elegraph wiretapping was
common, and an important intelligence source for both sides.” G.J.A. O’Toole,
The Encyclopedia of American Intelligence and Espionage 498 (1988). Confeder-
ate General J.E.B. Stuart even “had his own personal wiretapper travel along with
him in the field” to intercept military telegraphic communications. Samuel Dash et
al., The Eavesdroppers 23 (1971); see also O’Toole, American Intelligence at 121,
385–88, 496–98 (discussing Civil War surveillance methods such as wiretaps,
reconnaissance balloons, semaphore interception, and cryptanalysis). Similarly,
there was extensive use of electronic surveillance during the Spanish-American
War. See Bruce W. Bidwell, History of the Military Intelligence Division,
Department of the Army General Staff: 1775–1941, at 62 (1986). When an
American expeditionary force crossed into northern Mexico to confront the forces
of Pancho Villa in 1916, the Army “frequently intercepted messages of the regime
in Mexico City or the forces contesting its rule.” David Alvarez, Secret Messages
6–7 (2000). Shortly after Congress declared war on Germany in World War I,
President Wilson (citing only his constitutional powers and the joint resolution
declaring war) ordered the censorship of messages sent outside the United States
via submarine cables, telegraph, and telephone lines. See Exec. Order No. 2604
(Apr. 28, 1917), in 17 A Compilation of the Messages and Papers of the Presi-
dents 8254, 8254 (new series 1921). During that war, wireless telegraphy “enabled
each belligerent to tap the messages of the enemy.” Bidwell, Military Intelligence
Division at 165 (quoting statement of Col. W. Nicolai, former head of the Secret
Service of the High Command of the German Army, in W. Nicolai, The German
Secret Service 21 (1924)).
As noted in Part III.A, on May 21, 1940, President Roosevelt authorized war-
rantless electronic surveillance of persons suspected of subversive activities,
including spying, against the United States. In addition, on December 8, 1941, the
day after the attack on Pearl Harbor, President Roosevelt gave the Director of the
FBI “temporary powers to direct all news censorship and to control all other

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telecommunications traffic in and out of the United States.” Jack A. Gottschalk,
“Consistent with Security” . . . A History of American Military Press Censorship,
5 Comm. & L. 35, 39 (1983) (emphasis added). See Memorandum for the
Secretaries of War, Navy, State, and Treasury, the Postmaster General, and the
Federal Communications Commission from Franklin D. Roosevelt (Dec. 8, 1941).
President Roosevelt soon supplanted that temporary regime by establishing an
office for conducting such electronic surveillance in accordance with the War
Powers Act of 1941. See Pub. L. No. 77-354, § 303, 55 Stat. 838, 840–41 (Dec.
18, 1941); Gottschalk, Military Press Censorship, 5 Comm. & L. at 40. The
President’s order gave the government of the United States access to “communica-
tions by mail, cable, radio, or other means of transmission passing between the
United States and any foreign country.” Id.; see also Exec. Order No. 8985, § 1,
6 Fed. Reg. 6625, 6625 (Dec. 19, 1941). In addition, the United States systemati-
cally listened surreptitiously to electronic communications as part of the war
effort. See Dash, Eavesdroppers at 30. During World War II, signals intelligence
assisted in, among other things, the destruction of the German U-boat fleet by the
Allied naval forces, see id. at 27, and the war against Japan, see O’Toole, Ameri-
can Intelligence at 32, 323–24. In general, signals intelligence “helped to shorten
the war by perhaps two years, reduce the loss of life, and make inevitable an
eventual Allied victory.” Carl Boyd, American Command of the Sea Through
Carriers, Codes, and the Silent Service: World War II and Beyond 27 (1995); see
also Alvarez, Secret Messages at 1 (“There can be little doubt that signals
intelligence contributed significantly to the military defeat of the Axis.”). Signifi-
cantly, not only was wiretapping in World War II used “extensively by military
intelligence and secret service personnel in combat areas abroad,” but also “by the
FBI and secret service in this country.” Dash, Eavesdroppers at 30.
In light of the long history of prior wartime practice, the NSA activities fit
squarely within the sweeping terms of the AUMF. The use of signals intelligence
to identify and pinpoint the enemy is a traditional component of wartime military
operations—or, to use the terminology of Hamdi, a “fundamental and accepted . . .
incident to war,” 542 U.S. at 518 (plurality opinion)—employed to defeat the
enemy and to prevent enemy attacks in the United States. Here, as in other
conflicts, the enemy may use public communications networks, and some of the
enemy may already be in the United States. Although those factors may be present
in this conflict to a greater degree than in the past, neither is novel. Certainly, both
factors were well known at the time Congress enacted the AUMF. Wartime
interception of international communications made by the enemy thus should be
understood, no less than the wartime detention at issue in Hamdi, as one of the
basic methods of engaging and defeating the enemy that Congress authorized in
approving “all necessary and appropriate force” that the President would need to
defend the Nation. AUMF § 2(a) (emphasis added).

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 Legal Authorities Supporting the Activities of the National Security Agency

*****

Accordingly, the President has the authority to conduct warrantless electronic
surveillance against the declared enemy of the United States in a time of armed
conflict. That authority derives from the Constitution, and is reinforced by the text
and purpose of the AUMF, the nature of the threat posed by al Qaeda that
Congress authorized the President to repel, and the long-established understanding
that electronic surveillance is a fundamental incident of the use of military force.
The President’s power in authorizing the NSA activities is at its zenith because he
has acted “pursuant to an express or implied authorization of Congress.” Youngs-
town, 343 U.S. at 635 (Jackson, J., concurring).

C. The NSA Activities Are Consistent with the
Foreign Intelligence Surveillance Act

The President’s exercise of his constitutional authority to conduct warrantless
wartime electronic surveillance of the enemy, as confirmed and supplemented by
statute in the AUMF, is fully consistent with the requirements of the Foreign
Intelligence Surveillance Act (“FISA”). 5 FISA is a critically important tool in the
War on Terror. The United States makes full use of the authorities available under
FISA to gather foreign intelligence information, including authorities to intercept
communications, conduct physical searches, and install and use pen registers and
trap and trace devices. While FISA establishes certain procedures that must be
followed for these authorities to be used (procedures that usually involve applying
for and obtaining an order from a special court), FISA also expressly contemplates
that a later legislative enactment could authorize electronic surveillance outside the
procedures set forth in FISA itself. The AUMF constitutes precisely such an
enactment. To the extent there is any ambiguity on this point, the canon of
constitutional avoidance requires that such ambiguity be resolved in favor of the
President’s authority to conduct the communications intelligence activities he has
described. Finally, if FISA could not be read to allow the President to authorize
the NSA activities during the current congressionally authorized armed conflict
with al Qaeda, FISA would be unconstitutional as applied in this narrow context.

1. The Requirements of FISA

FISA was enacted in 1978 to regulate “electronic surveillance,” particularly
when conducted to obtain “foreign intelligence information,” as those terms are
defined in section 101 of FISA, 50 U.S.C. § 1801. As a general matter, the statute
requires that the Attorney General approve an application for an order from a

5
To avoid revealing details about the operation of the program, it is assumed for purposes of this
paper that the activities described by the President constitute “electronic surveillance,” as defined by
FISA, 50 U.S.C. § 1801(f).

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special court composed of Article III judges and created by FISA—the Foreign
Intelligence Surveillance Court (“FISC”). 50 U.S.C. §§ 1803–1804. The applica-
tion must demonstrate, among other things, that there is probable cause to believe
that the target is a foreign power or an agent of a foreign power. Id.
§ 1805(a)(3)(A). It must also contain a certification from the Assistant to the
President for National Security Affairs or an officer of the United States appointed
by the President with the advice and consent of the Senate and having responsibili-
ties in the area of national security or defense that the information sought is
foreign intelligence information and cannot reasonably be obtained by normal
investigative means. Id. § 1804(a)(7). FISA further requires the government to
state the means that it proposes to use to obtain the information and the basis for
its belief that the facilities at which the surveillance will be directed are being used
or are about to be used by a foreign power or an agent of a foreign power. Id.
§ 1804(a)(4), (a)(8).
FISA was the first congressional measure that sought to impose restrictions on
the Executive Branch’s authority to engage in electronic surveillance for foreign
intelligence purposes, an authority that, as noted above, had been repeatedly
recognized by the federal courts. See Americo R. Cinquegrana, The Walls (and
Wires) Have Ears: The Background and First Ten Years of the Foreign Intelli-
gence Surveillance Act of 1978, 137 U. Penn. L. Rev. 793, 810 (1989) (stating that
the “status of the President’s inherent authority” to conduct surveillance “formed
the core of subsequent legislative deliberations” leading to the enactment of
FISA). To that end, FISA modified a provision in Title III that previously had
disclaimed any intent to have laws governing wiretapping interfere with the
President’s constitutional authority to gather foreign intelligence. Prior to the
passage of FISA, section 2511(3) of title 18 had stated that “[n]othing contained in
this chapter or in section 605 of the Communications Act of 1934 . . . shall limit
the constitutional power of the President to take such measures as he deems
necessary to protect the Nation against actual or potential attack or other hostile
acts of a foreign power, to obtain foreign intelligence information deemed
essential to the security of the United States, or to protect national security
information against foreign intelligence activities.” 18 U.S.C. § 2511(3) (1970).
FISA replaced that provision with an important, though more limited, preservation
of authority for the President. See Pub. L. No. 95-511, § 201(b), (c), 92 Stat. 1783,
1797 (1978), as added, 18 U.S.C. § 2511(2)(f) (Supp. IV 2005) (carving out from
statutory regulation only the acquisition of intelligence information from “interna-
tional or foreign communications” and “foreign intelligence activities . . . involv-
ing a foreign electronic communications system” as long as they are accomplished
“utilizing a means other than electronic surveillance as defined in section 101” of

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 Legal Authorities Supporting the Activities of the National Security Agency

FISA). Congress also defined “electronic surveillance,” 50 U.S.C. § 1801(f), care-
fully and somewhat narrowly. 6
In addition, Congress addressed, to some degree, the manner in which FISA
might apply after a formal declaration of war by expressly allowing warrantless
surveillance for a period of fifteen days following such a declaration. Section 111
of FISA allows the President to “authorize electronic surveillance without a court
order under this subchapter to acquire foreign intelligence information for a period
not to exceed fifteen calendar days following a declaration of war by the Con-
gress.” 50 U.S.C. § 1811.
The legislative history of FISA shows that Congress understood it was legislat-
ing on fragile constitutional ground and was pressing or even exceeding constitu-
tional limits in regulating the President’s authority in the field of foreign intelli-
gence. The final House Conference Report, for example, recognized that the
statute’s restrictions might well impermissibly infringe on the President’s constitu-
tional powers. That report includes the extraordinary acknowledgment that “[t]he
conferees agree that the establishment by this act of exclusive means by which the
President may conduct electronic surveillance does not foreclose a different
decision by the Supreme Court.” H.R. Conf. Rep. No. 95-1720, at 35, reprinted in
1978 U.S.C.C.A.N. 4048, 4064. But, invoking Justice Jackson’s concurrence in
the Steel Seizure Case, the Conference Report explained that Congress intended in
FISA to exert whatever power Congress constitutionally had over the subject
matter to restrict foreign intelligence surveillance and to leave the President solely
with whatever inherent constitutional authority he might be able to invoke against

6
FISA’s legislative history reveals that these provisions were intended to exclude certain intelli-
gence activities conducted by the National Security Agency from the coverage of FISA. According to
the report of the Senate Judiciary Committee on FISA, “this provision [referencing what became the
first part of section 2511(2)(f)] is designed to make clear that the legislation does not deal with
international signals intelligence activities as currently engaged in by the National Security Agency and
electronic surveillance conducted outside the United States.” S. Rep. No. 95-604, at 64 (1978),
reprinted in 1978 U.S.C.C.A.N. 3904, 3965. The legislative history also makes clear that the definition
of “electronic surveillance” was crafted for the same reason. See id. at 33–34, 1978 U.S.C.C.A.N. at
3934–36. FISA thereby “adopts the view expressed by the Attorney General during the hearings that
enacting statutory controls to regulate the National Security Agency and the surveillance of Americans
abroad raises problems best left to separate legislation.” Id. at 64, 1978 U.S.C.C.A.N. at 3965. Such
legislation placing limitations on traditional NSA activities was drafted, but never passed. See National
Intelligence Reorganization and Reform Act of 1978: Hearings Before the S. Select Comm. on
Intelligence, 95th Cong. 999–1007 (1978) (text of unenacted legislation). And Congress understood
that the NSA surveillance that it intended categorically to exclude from FISA could include the
monitoring of international communications into or out of the United States of U.S. citizens. The report
specifically referred to the Church Committee report for its description of the NSA’s activities, S. Rep.
No. 95-604, at 64 n.63, 1978 U.S.C.C.A.N. at 3965–66 n.63, which stated that “the NSA intercepts
messages passing over international lines of communication, some of which have one terminal within
the United States. Traveling over these lines of communication, especially those with one terminal in
the United States, are messages of Americans . . . .” S. Rep. No. 94-755, bk. II, at 308 (1976).
Congress’s understanding in the legislative history of FISA that such communications could be
intercepted outside FISA procedures is notable.

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 Opinions of the Office of Legal Counsel in Volume 30

Congress’s express wishes. Id. The Report thus explains that “[t]he intent of the
conferees is to apply the standard set forth in Justice Jackson’s concurring opinion
in the Steel Seizure Case: ‘When a President takes measures incompatible with the
express or implied will of Congress, his power is at the lowest ebb, for then he can
rely only upon his own constitutional power minus any constitutional power of
Congress over the matter.’” Id. (quoting Youngstown Sheet & Tube Co. v. Sawyer,
343 U.S. 579, 637 (1952) (Jackson, J., concurring)); see also S. Rep. No. 95-604,
at 64, reprinted in 1978 U.S.C.C.A.N. at 3966 (same); see generally Elizabeth B.
Bazen & Jennifer K. Elsea, Cong. Research Serv., Presidential Authority to
Conduct Warrantless Electronic Surveillance to Gather Foreign Intelligence
Information 28–29 (Jan. 5, 2006). It is significant, however, that Congress did not
decide conclusively to continue to push the boundaries of its constitutional
authority in wartime. Instead, Congress reserved the question of the appropriate
procedures to regulate electronic surveillance in time of war, and established a
fifteen-day period during which the President would be permitted to engage in
electronic surveillance without complying with FISA’s express procedures and
during which Congress would have the opportunity to revisit the issue. See 50
U.S.C. § 1811; H.R. Conf. Rep. No. 95-1720, at 34, reprinted in 1978
U.S.C.C.A.N. at 4063 (noting that the purpose of the fifteen-day period following
a declaration of war in section 111 of FISA was to “allow time for consideration of
any amendment to this act that may be appropriate during a wartime emergency”).

2. FISA Contemplates and Allows Surveillance
Authorized “By Statute”

Congress did not attempt through FISA to prohibit the Executive Branch from
using electronic surveillance. Instead, Congress acted to bring the exercise of that
power under more stringent congressional control. See, e.g., H.R. Conf. Rep. No.
95-1720, at 32, reprinted in 1978 U.S.C.C.A.N. 4048, 4064. Congress therefore
enacted a regime intended to supplant the President’s reliance on his own constitu-
tional authority. Consistent with this overriding purpose of bringing the use of
electronic surveillance under congressional control and with the commonsense
notion that the Congress that enacted FISA could not bind future congresses, FISA
expressly contemplates that the Executive Branch may conduct electronic
surveillance outside FISA’s express procedures if and when a subsequent statute
authorizes such surveillance.
Thus, section 109 of FISA prohibits any person from intentionally “en-
gag[ing] . . . in electronic surveillance under color of law except as authorized by
statute.” 50 U.S.C. § 1809(a)(1) (emphasis added). Because FISA’s prohibitory
provision broadly exempts surveillance “authorized by statute,” the provision
demonstrates that Congress did not attempt to regulate through FISA electronic
surveillance authorized by Congress through a subsequent enactment. The use of
the term “statute” here is significant because it strongly suggests that any subse-

24
 Legal Authorities Supporting the Activities of the National Security Agency

quent authorizing statute, not merely one that amends FISA itself, could legiti-
mately authorize surveillance outside FISA’s standard procedural requirements.
Compare 18 U.S.C. § 2511(1) (“Except as otherwise specifically provided in this
chapter any person who—(a) intentionally intercepts . . . any wire, oral, or
electronic communication[] . . . shall be punished . . . .”) (emphasis added); id.
§ 2511(2)(e) (providing a defense to liability to individuals “conduct[ing] electron-
ic surveillance, . . . as authorized by that Act [FISA]”) (emphasis added). In
enacting FISA, therefore, Congress contemplated the possibility that the President
might be permitted to conduct electronic surveillance pursuant to a later-enacted
statute that did not incorporate all of the procedural requirements set forth in FISA
or that did not expressly amend FISA itself.
To be sure, the scope of this exception is rendered less clear by the conforming
amendments that FISA made to chapter 119 of title 18—the portion of the criminal
code that provides the mechanism for obtaining wiretaps for law enforcement
purposes. Before FISA was enacted, chapter 119 made it a criminal offense for
any person to intercept a communication except as specifically provided in that
chapter. See 18 U.S.C. § 2511(1)(a), (4)(a). Section 201(b) of FISA amended that
chapter to provide an exception from criminal liability for activities conducted
pursuant to FISA. Specifically, FISA added 18 U.S.C. § 2511(2)(e), which
provides that it is not unlawful for “an officer, employee, or agent of the United
States . . . to conduct electronic surveillance, as defined in section 101 of the
Foreign Intelligence Surveillance Act of 1978, as authorized by that Act.”
Similarly, section 201(b) of FISA amended chapter 119 to provide that “proce-
dures in this chapter [or chapter 121 (addressing access to stored wire and
electronic communications and customer records)] and the Foreign Intelligence
Surveillance Act of 1978 shall be the exclusive means by which electronic
surveillance, as defined in section 101 of such Act, and the interception of
domestic wire, oral, and electronic communications may be conducted.” Id.
§ 2511(2)(f) (Supp. IV 2005). 7
The amendments that section 201(b) of FISA made to title 18 are fully con-
sistent, however, with the conclusion that FISA contemplates that a subsequent
statute could authorize electronic surveillance outside FISA’s express procedural
requirements. Section 2511(2)(e) of title 18, which provides that it is “not
unlawful” for an officer of the United States to conduct electronic surveillance “as
authorized by” FISA, is best understood as a safe-harbor provision. Because of
section 109, the protection offered by section 2511(2)(e) for surveillance “author-
ized by” FISA extends to surveillance that is authorized by any other statute and
therefore excepted from the prohibition of section 109. In any event, the purpose
of section 2511(2)(e) is merely to make explicit what would already have been

7
The bracketed portion was added in 1986 amendments to section 2511(2)(f). See Pub. L. No. 99-
508, § 101(b)(3), 100 Stat. 1848, 1850.

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 Opinions of the Office of Legal Counsel in Volume 30

implicit—that those authorized by statute to engage in particular surveillance do
not act unlawfully when they conduct such surveillance. Thus, even if that
provision had not been enacted, an officer conducting surveillance authorized by
statute (whether FISA or some other law) could not reasonably have been thought
to be violating Title III. Similarly, section 2511(2)(e) cannot be read to require a
result that would be manifestly unreasonable—exposing a federal officer to
criminal liability for engaging in surveillance authorized by statute, merely
because the authorizing statute happens not to be FISA itself.
Nor could 18 U.S.C. § 2511(2)(f), which provides that the “procedures in this
chapter . . . and the Foreign Intelligence Surveillance Act of 1978 shall be the
exclusive means by which electronic surveillance . . . may be conducted,” have
been intended to trump the commonsense approach of section 109 and preclude a
subsequent congress from authorizing the President to engage in electronic
surveillance through a statute other than FISA, using procedures other than those
outlined in FISA or chapter 119 of title 18. The legislative history of section
2511(2)(f) clearly indicates an intent to prevent the President from engaging in
surveillance except as authorized by Congress, see H.R. Conf. Rep. No. 95-1720,
at 32, reprinted in 1978 U.S.C.C.A.N. 4048, 4064, which explains why section
2511(2)(f) set forth all then-existing statutory restrictions on electronic surveil-
lance. Section 2511(2)(f)’s reference to “exclusive means” reflected the state of
statutory authority for electronic surveillance in 1978 and cautioned the President
not to engage in electronic surveillance outside congressionally sanctioned
parameters. It is implausible to think that, in attempting to limit the President’s
authority, Congress also limited its own future authority by barring subsequent
congresses from authorizing the Executive to engage in surveillance in ways not
specifically enumerated in FISA or chapter 119, or by requiring a subsequent
congress specifically to amend FISA and section 2511(2)(f). There would be a
serious question as to whether the Ninety-Fifth Congress could have so tied the
hands of its successors. See, e.g., Fletcher v. Peck, 10 U.S. (6 Cranch) 87, 135
(1810) (noting that “one legislature cannot abridge the powers of a succeeding
legislature”); Reichelderfer v. Quinn, 287 U.S. 315, 318 (1932) (“[T]he will of a
particular Congress . . . does not impose itself upon those to follow in succeeding
years”); Lockhart v. United States, 546 U.S. 142, 147–48 (2005) (Scalia, J.,
concurring) (collecting precedent); 1 William Blackstone, Commentaries *90
(“Acts of parliament derogatory from the power of subsequent parliaments bind
not”). In the absence of a clear statement to the contrary, it cannot be presumed
that Congress attempted to abnegate its own authority in such a way.
Far from a clear statement of congressional intent to bind itself, there are indi-
cations that section 2511(2)(f) cannot be interpreted as requiring that all electronic
surveillance and domestic interception be conducted under FISA’s enumerated
procedures or those of chapter 119 of title 18 until and unless those provisions are
repealed or amended. Even when section 2511(2)(f) was enacted (and no subse-
quent authorizing statute existed), it could not reasonably be read to preclude all

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 Legal Authorities Supporting the Activities of the National Security Agency

electronic surveillance conducted outside the procedures of FISA or chapter 119 of
title 18. In 1978, use of a pen register or trap and trace device constituted electron-
ic surveillance as defined by FISA. See 50 U.S.C. §§ 1801(f), (n). Title I of FISA
provided procedures for obtaining court authorization for the use of pen registers
to obtain foreign intelligence information. But the Supreme Court had, just prior to
the enactment of FISA, held that chapter 119 of title 18 did not govern the use of
pen registers. See United States v. N.Y. Tel. Co., 434 U.S. 159, 165–68 (1977).
Thus, if section 2511(2)(f) were to be read to permit of no exceptions, the use of
pen registers for purposes other than to collect foreign intelligence information
would have been unlawful because such use would not have been authorized by
the “exclusive” procedures of section 2511(2)(f), i.e., FISA and chapter 119. But
no court has held that pen registers could not be authorized outside the foreign
intelligence context. Indeed, FISA appears to have recognized this issue by
providing a defense to liability for any official who engages in electronic surveil-
lance under a search warrant or court order. See 50 U.S.C. § 1809(b). (The practice
when FISA was enacted was for law enforcement officers to obtain search
warrants under the Federal Rules of Criminal Procedure authorizing the installa-
tion and use of pen registers. See S. 1667, A Bill to Amend Title 18, United States
Code, with Respect to the Interception of Certain Communications, Other Forms
of Surveillance, and for Other Purposes: Hearing Before the Subcomm. On
Patents, Copyrights and Trademarks of the S. Comm. on the Judiciary, 99th Cong.
57 (1985) (prepared statement of James Knapp, Deputy Assistant Attorney
General, Criminal Division). 8)
In addition, section 2511(2)(a)(ii) authorizes telecommunications providers to
assist officers of the government engaged in electronic surveillance when the
Attorney General certifies that “no warrant or court order is required by law [and]
that all statutory requirements have been met.” 18 U.S.C. § 2511(2)(a)(ii). 9 If the
Attorney General can certify, in good faith, that the requirements of a subsequent
statute authorizing electronic surveillance are met, service providers are affirma-
tively and expressly authorized to assist the government. Although FISA does

8
Alternatively, section 109(b) may be read to constitute a “procedure” in FISA or to incorporate
procedures from sources other than FISA (such as the Federal Rules of Criminal Procedure or state
court procedures), and in that way to satisfy section 2511(2)(f). But if section 109(b)’s defense can be
so read, section 109(a) should also be read to constitute a procedure or incorporate procedures not
expressly enumerated in FISA.
9
Section 2511(2)(a)(ii) states:
Notwithstanding any other law, providers of wire or electronic communication ser-
vice, . . . are authorized by law to provide information, facilities, or technical assis-
tance to persons authorized by law to intercept . . . communications or to conduct elec-
tronic surveillance, as defined [by FISA], if such provider . . . has been provided
with . . . a certification in writing by [specified persons proceeding under Title III’s
emergency provision] or the Attorney General of the United States that no warrant or
court order is required by law, that all statutory requirements have been met, and that
the specific assistance is required.

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 Opinions of the Office of Legal Counsel in Volume 30

allow the government to proceed without a court order in several situations, see 50
U.S.C. § 1805(f) (emergencies); id. § 1802 (certain communications between
foreign governments), this provision specifically lists only Title III’s emergency
provision but speaks generally to Attorney General certification. That reference to
Attorney General certification is consistent with the historical practice in which
Presidents have delegated to the Attorney General authority to approve warrantless
surveillance for foreign intelligence purposes. See, e.g., United States v. U.S. Dist.
Ct., 444 F.2d 651, 669–71 (6th Cir. 1971) (reproducing as an appendix memoran-
da from Presidents Roosevelt, Truman, and Johnson). Section 2511(2)(a)(ii) thus
suggests that telecommunications providers can be authorized to assist with
warrantless electronic surveillance when such surveillance is authorized by law
outside FISA.
In sum, by expressly and broadly excepting from its prohibition electronic
surveillance undertaken “as authorized by statute,” section 109 of FISA permits an
exception to the “procedures” of FISA referred to in 18 U.S.C. § 2511(2)(f) where
authorized by another statute, even if the other authorizing statute does not
specifically amend section 2511(2)(f).

3. The AUMF Is a “Statute” Authorizing Surveillance
Outside the Confines of FISA

The AUMF qualifies as a “statute” authorizing electronic surveillance within
the meaning of section 109 of FISA.
First, because the term “statute” historically has been given broad meaning, the
phrase “authorized by statute” in section 109 of FISA must be read to include joint
resolutions such as the AUMF. See Am. Fed’n of Labor v. Watson, 327 U. S. 582,
592–93 (1946) (finding the term “statute” as used in 28 U.S.C. § 380 to mean “a
compendious summary of various enactments, by whatever method they may be
adopted, to which a State gives her sanction”); Black’s Law Dictionary 1410 (6th
ed. 1990) (defining “statute” broadly to include any “formal written enactment of a
legislative body,” and stating that the term is used “to designate the legislatively
created laws in contradistinction to court decided or unwritten laws”). It is thus of
no significance to this analysis that the AUMF was enacted as a joint resolution
rather than a bill. See, e.g., Ann Arbor R.R. Co. v. United States, 281 U.S. 658, 666
(1930) (joint resolutions are to be construed by applying “the rules applicable to
legislation in general”); United States ex rel. Levey v. Stockslager, 129 U.S. 470,
475 (1889) (joint resolution had “all the characteristics and effects” of statute that
it suspended); Padilla ex rel. Newman v. Bush, 233 F. Supp. 2d 564, 598 (S.D.N.Y
2002) (in analyzing the AUMF, finding that there is “no relevant constitutional
difference between a bill and a joint resolution”), rev’d on other grounds sub nom.
Rumsfeld v. Padilla, 352 F.3d 695 (2d Cir. 2003), rev’d, 542 U.S. 426 (2004); see
also Letter for John Conyers, Jr., U.S. House of Representatives, from Laurence

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 Legal Authorities Supporting the Activities of the National Security Agency

H. Tribe at 3 (Jan. 6, 2006) (term “statute” in section 109 of FISA “of course
encompasses a joint resolution presented to and signed by the President”).
Second, the longstanding history of communications intelligence as a funda-
mental incident of the use of force and the Supreme Court’s decision in Hamdi v.
Rumsfeld strongly suggest that the AUMF satisfies the requirement of section 109
of FISA for statutory authorization of electronic surveillance. As explained above,
it is not necessary to demarcate the outer limits of the AUMF to conclude that it
encompasses electronic surveillance targeted at the enemy. Just as a majority of
the Court concluded in Hamdi that the AUMF authorizes detention of U.S. citizens
who are enemy combatants without expressly mentioning the President’s long-
recognized power to detain, so too does it authorize the use of electronic surveil-
lance without specifically mentioning the President’s equally long-recognized
power to engage in communications intelligence targeted at the enemy. And just as
the AUMF satisfies the requirement in 18 U.S.C. § 4001(a) that no U.S. citizen be
detained “except pursuant to an Act of Congress,” so too does it satisfy section
109’s requirement for statutory authorization of electronic surveillance. 10 In
authorizing the President’s use of force in response to the September 11th attacks,
Congress did not need to comb through the United States Code looking for those
restrictions that it had placed on national security operations during times of peace
and designate with specificity each traditional tool of military force that it sought
to authorize the President to use. There is no historical precedent for such a
requirement: authorizations to use military force traditionally have been couched
in general language. Indeed, prior administrations have interpreted joint resolu-
tions declaring war and authorizing the use of military force to authorize expan-
sive collection of communications into and out of the United States. 11

10
It might be argued that Congress dealt more comprehensively with electronic surveillance in
FISA than it did with detention in 18 U.S.C. § 4001(a). Thus, although Congress prohibited detention
“except pursuant to an Act of Congress,” it combined the analogous prohibition in FISA (section
109(a)) with section 2511(2)(f)’s exclusivity provision. See Letter for Bill Frist, Majority Leader, U.S.
Senate, from Curtis A. Bradley et al. at 5 n.6 (Jan. 9, 2006) (noting that section 4001(a) does not
“attempt[] to create an exclusive mechanism for detention”). On closer examination, however, it is
evident that Congress has regulated detention far more meticulously than these arguments suggest.
Detention is the topic of much of the Criminal Code, as well as a variety of other statutes, including
those providing for civil commitment of the mentally ill and confinement of alien terrorists. The
existence of these statutes and accompanying extensive procedural safeguards, combined with the
substantial constitutional issues inherent in detention, see, e.g., Hamdi, 542 U.S. at 574–75 (Scalia, J.,
dissenting), refute any such argument.
11
As noted above, in intercepting communications, President Wilson relied on his constitutional
authority and the joint resolution declaring war and authorizing the use of military force, which, as
relevant here, provided “that the President [is] authorized and directed to employ the entire naval and
military forces of the United States and the resources of the Government to carry on war against the
Imperial German Government; and to bring the conflict to a successful termination all of the resources
of the country are hereby pledged by the Congress of the United States.” Joint Resolution of Apr. 6,
1917, ch. 1, 40 Stat. 1. The authorization did not explicitly mention interception of communications.

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Moreover, crucial to the Framers’ decision to vest the President with primary
constitutional authority to defend the Nation from foreign attack is the fact that the
Executive can act quickly, decisively, and flexibly as needed. For Congress to
have a role in that process, it must be able to act with similar speed, either to lend
its support to, or to signal its disagreement with, proposed military action. Yet the
need for prompt decisionmaking in the wake of a devastating attack on the United
States is fundamentally inconsistent with the notion that to do so Congress must
legislate at a level of detail more in keeping with a peacetime budget reconciliation
bill. In emergency situations, Congress must be able to use broad language that
effectively sanctions the President’s use of the core incidents of military force.
That is precisely what Congress did when it passed the AUMF on September 14,
2001—just three days after the deadly attacks on America. The Capitol had been
evacuated on September 11th, and Congress was meeting in scattered locations.
As an account emerged of who might be responsible for these attacks, Congress
acted quickly to authorize the President to use “all necessary and appropriate
force” against the enemy that he determines was involved in the September 11th
attacks. Under these circumstances, it would be unreasonable and wholly imprac-
tical to demand that Congress specifically amend FISA in order to assist the
President in defending the Nation. Such specificity would also have been self-
defeating because it would have apprised our adversaries of some of our most
sensitive methods of intelligence gathering. 12
Section 111 of FISA, 50 U.S.C. § 1811, which authorizes the President,
“[n]otwithstanding any other law,” to conduct “electronic surveillance without a
court order under this subchapter to acquire foreign intelligence information for a
period not to exceed fifteen calendar days following a declaration of war by
Congress,” does not require a different reading of the AUMF. See also id. § 1844
(same provision for pen registers); id. § 1829 (same provision for physical
searches). Section 111 cannot reasonably be read as Congress’s final word on
electronic surveillance during wartime, thus permanently limiting the President in
all circumstances to a mere fifteen days of warrantless military intelligence
gathering targeted at the enemy following a declaration of war. Rather, section 111
represents Congress’s recognition that it would likely have to return to the subject
and provide additional authorization to conduct warrantless electronic surveillance

12
Some have suggested that the Administration declined to seek a specific amendment to FISA
allowing the NSA activities “because it was advised that Congress would reject such an amendment,”
Letter for Bill Frist, Majority Leader, U.S. Senate, from Curtis A. Bradley et al. at 4 & n.4 (Jan. 9,
2005), and they have quoted in support of that assertion the Attorney General’s statement that certain
members of Congress advised the Administration that legislative relief “would be difficult, if not
impossible.” Id. at 4 n.4. As the Attorney General subsequently indicated, however, the difficulty with
such specific legislation was that it could not be enacted “without compromising the program.” See
Transcript of Attorney General Alberto R. Gonzales and Homeland Security Secretary Michael
Chertoff Press Briefing on Need for Senate to Reauthorize the USA PATRIOT Act (Dec. 21, 2005),
(available at http://www.justice.gov/ag/readingroom/surveillance5.pdf, last visited Apr. 11, 2014).

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 Legal Authorities Supporting the Activities of the National Security Agency

outside FISA during time of war. The Conference Report explicitly stated the
conferees’ “inten[t] that this [fifteen-day] period will allow time for consideration
of any amendment to this act that may be appropriate during a wartime emergen-
cy.” H.R. Conf. Rep. No. 95-1720, at 34, reprinted in 1978 U.S.C.C.A.N. at 4063.
Congress enacted section 111 so that the President could conduct warrantless
surveillance while Congress considered supplemental wartime legislation.
Nothing in the terms of section 111 disables Congress from authorizing such
electronic surveillance as a traditional incident of war through a broad, conflict-
specific authorization for the use of military force, such as the AUMF. Although
the legislative history of section 111 indicates that in 1978 some members of
Congress believed that any such authorization would come in the form of a
particularized amendment to FISA itself, section 111 does not require that result.
Nor could the Ninety-Fifth Congress tie the hands of a subsequent congress in this
way, at least in the absence of far clearer statutory language expressly requiring
that result. See supra Part III.C.2; compare, e.g., War Powers Resolution § 8, 50
U.S.C. § 1547(a) (“Authority to introduce United States Armed Forces into
hostilities . . . shall not be inferred . . . from any provision of law . . . unless such
provision specifically authorizes [such] introduction . . . and states that it is
intended to constitute specific statutory authorization within the meaning of this
chapter.”); 10 U.S.C. § 401 (stating that any other provision of law providing
assistance to foreign countries to detect and clear landmines shall be subject to
specific limitations and may be construed as superseding such limitations “only if,
and to the extent that, such provision specifically refers to this section and
specifically identifies the provision of this section that is to be considered super-
seded or otherwise inapplicable”). An interpretation of section 111 that would
disable Congress from authorizing broader electronic surveillance in that form can
be reconciled neither with the purposes of section 111 nor with the well-
established proposition that “one legislature cannot abridge the powers of a
succeeding legislature.” Fletcher v. Peck, 10 U.S. (6 Cranch) at 135; see supra
Part III.B.2. For these reasons, the better interpretation is that section 111 was not
intended to, and did not, foreclose Congress from using the AUMF as the legal
vehicle for supplementing the President’s existing authority under FISA in the
battle against al Qaeda.
The contrary interpretation of section 111 also ignores the important differ-
ences between a formal declaration of war and a resolution such as the AUMF. As
a historical matter, a formal declaration of war was no longer than a sentence, and
thus Congress would not expect a declaration of war to outline the extent to which
Congress authorized the President to engage in various incidents of waging war.
Authorizations for the use of military force, by contrast, are typically more
detailed and are made for the specific purpose of reciting the manner in which
Congress has authorized the President to act. Thus, Congress could reasonably
expect that an authorization for the use of military force would address the issue of
wartime surveillance, while a declaration of war would not. Here, the AUMF

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declares that the Nation faces “an unusual and extraordinary threat,” acknowledges
that “the President has authority under the Constitution to take action to deter and
prevent acts of international terrorism against the United States,” and provides that
the President is authorized “to use all necessary and appropriate force” against
those “he determines” are linked to the September 11th attacks. AUMF pmbl., § 2.
This sweeping language goes far beyond the bare terms of a declaration of war.
Compare, e.g., Act of Apr. 25, 1898, ch. 189, 30 Stat. 364 (“First. That war be,
and the same is hereby declared to exist . . . between the United States of America
and the Kingdom of Spain.”).
Although legislation that has included a declaration of war has often also in-
cluded an authorization of the President to use force, these provisions are separate
and need not be combined in a single statute. See, e.g., id. (“Second. That the
President of the United States be, and he hereby is, directed and empowered to use
the entire land and naval forces of the United States, and to call into the actual
service of the United States the militia of the several states, to such extent as may
be necessary to carry this Act into effect.”) (emphasis added). Moreover, declara-
tions of war have legal significance independent of any additional authorization of
force that might follow. See, e.g., Louis Henkin, Foreign Affairs and the U.S.
Constitution 75 (2d ed. 1996) (explaining that a formal state of war has various
legal effects, such as terminating diplomatic relations, and abrogating or suspend-
ing treaty obligations and international law rights and duties); see also id. at 370
n.65 (speculating that one reason to fight an undeclared war would be to “avoid
the traditional consequences of declared war on relations with third nations or
even . . . belligerents”).
In addition, section 111 does not cover the vast majority of modern military
conflicts. The last declared war was World War II. Indeed, the most recent conflict
prior to the passage of FISA, Vietnam, was fought without a formal declaration of
war. In addition, the War Powers Resolution, enacted less than five years before
FISA, clearly recognizes the distinctions between formal declarations of war and
authorizations of force and demonstrates that, if Congress had wanted to include
such authorizations in section 111, it knew how to do so. See, e.g., 50 U.S.C.
§ 1544(b) (attempting to impose certain consequences 60 days after reporting the
initiation of hostilities to Congress “unless the Congress . . . has declared war or
has enacted a specific authorization for such use” of military force) (emphasis
added). It is possible that, in enacting section 111, Congress intended to make no
provision for even the temporary use of electronic surveillance without a court
order for what had become the legal regime for most military conflicts. A better
reading, however, is that Congress assumed that such a default provision would be
unnecessary because, if it had acted through an authorization for the use of
military force, the more detailed provisions of that authorization would resolve the

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extent to which Congress would attempt to authorize, or withhold authorization
for, the use of electronic surveillance. 13

*****

The broad text of the AUMF, the authoritative interpretation that the Supreme
Court gave it in Hamdi, and the circumstances in which it was passed demonstrate
that the AUMF is a statute authorizing electronic surveillance under section 109 of
FISA. When the President authorizes electronic surveillance against the enemy
pursuant to the AUMF, he is therefore acting at the height of his authority under
Youngstown, 343 U.S. at 637 (Jackson, J., concurring).

13
Some have pointed to the specific amendments to FISA that Congress made shortly after Sep-
tember 11th in the USA PATRIOT Act, Pub. L. No. 107-56, §§ 204, 218, 115 Stat. 272, 281, 291
(2001), to argue that Congress did not contemplate electronic surveillance outside the parameters of
FISA. See Memorandum for Members of the House Permanent Select Committee on Intelligence, from
Jeffrey H. Smith, Re: Legal Authorities Regarding Warrantless Surveillance of U.S. Persons at 6–7
(Jan. 3, 2006). The USA PATRIOT Act amendments, however, do not justify giving the AUMF an
unnaturally narrow reading. The USA PATRIOT Act amendments made important corrections in the
general application of FISA; they were not intended to define the precise incidents of military force that
would be available to the President in prosecuting the current armed conflict against al Qaeda and its
allies. Many removed long-standing impediments to the effectiveness of FISA that had contributed to
the maintenance of an unnecessary “wall” between foreign intelligence gathering and criminal law
enforcement; others were technical clarifications. See In re Sealed Case, 310 F.3d 717, 725–30 (FISA
Ct. Rev. 2002). The “wall” had been identified as a significant problem hampering the government’s
efficient use of foreign intelligence information well before the September 11th attacks and in contexts
unrelated to terrorism. See, e.g., Final Report of the Attorney General’s Review Team on the Handling
of the Los Alamos National Laboratory Investigation 710, 729, 732 (May 2000); U.S. General
Accounting Office, GAO-01-780, FBI Intelligence Investigations: Coordination Within Justice on
Counterintelligence Criminal Matters Is Limited 3, 31 (July 2001). Finally, it is worth noting that
Justice Souter made a similar argument in Hamdi that the USA PATRIOT Act all but compelled a
narrow reading of the AUMF. See 542 U.S. at 551 (“It is very difficult to believe that the same
Congress that carefully circumscribed Executive power over alien terrorists on home soil [in the USA
PATRIOT Act] would not have meant to require the Government to justify clearly its detention of an
American citizen held on home soil incommunicado.”). Only Justice Ginsburg joined this opinion, and
the position was rejected by a majority of justices.
Nor do later amendments to FISA undermine the conclusion that the AUMF authorizes electronic
surveillance outside the procedures of FISA. Three months after the enactment of the AUMF, Congress
enacted certain “technical amendments” to FISA which, inter alia, extended the time during which the
Attorney General may issue an emergency authorization of electronic surveillance from 24 to 72 hours.
See Intelligence Authorization Act for Fiscal Year 2002, Pub. L. No. 107-108, § 314, 115 Stat. 1394,
1402 (2001). These modifications to FISA do not in any way undermine Congress’s previous
authorization in the AUMF for the President to engage in electronic surveillance outside the parameters
of FISA in the specific context of the armed conflict with al Qaeda.

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4. The Canon of Constitutional Avoidance Requires Resolving in
Favor of the President’s Authority Any Ambiguity About
Whether FISA Forbids the NSA Activities

As explained above, the AUMF fully authorizes the NSA activities. Because
FISA contemplates the possibility that subsequent statutes could authorize
electronic surveillance without requiring FISA’s standard procedures, the NSA
activities are also consistent with FISA and related provisions in title 18. Never-
theless, some might argue that sections 109 and 111 of FISA, along with section
2511(2)(f)’s “exclusivity” provision and section 2511(2)(e)’s liability exception
for officers engaged in FISA-authorized surveillance, are best read to suggest that
FISA requires that subsequent authorizing legislation specifically amend FISA in
order to free the Executive from FISA’s enumerated procedures. As detailed
above, this is not the better reading of FISA. But even if these provisions were
ambiguous, any doubt as to whether the AUMF and FISA should be understood to
allow the President to make tactical military decisions to authorize surveillance
outside the parameters of FISA must be resolved to avoid the serious constitution-
al questions that a contrary interpretation would raise.
It is well established that the first task of any interpreter faced with a statute
that may present an unconstitutional infringement on the powers of the President is
to determine whether the statute may be construed to avoid the constitutional
difficulty. “[I]f an otherwise acceptable construction of a statute would raise
serious constitutional problems, and where an alternative interpretation of the
statute is ‘fairly possible,’ we are obligated to construe the statute to avoid such
problems.” INS v. St. Cyr, 533 U.S. 289, 299–300 (2001) (citations omitted); Ash-
wander v. TVA, 297 U.S. 288, 345–48 (1936) (Brandeis, J., concurring). More-
over, the canon of constitutional avoidance has particular importance in the realm
of national security, where the President’s constitutional authority is at its highest.
See Dep’t of Navy v. Egan, 484 U.S. 518, 527, 530 (1988); William N. Eskridge,
Jr., Dynamic Statutory Interpretation 325 (1994) (describing “[s]uper-strong rule
against congressional interference with the President’s authority over foreign
affairs and national security”). Thus, courts and the Executive Branch typically
construe a general statute, even one that is written in unqualified terms, to be
implicitly limited so as not to infringe on the President’s Commander in Chief
powers.
Reading FISA to prohibit the NSA activities would raise two serious constitu-
tional questions, both of which must be avoided if possible: (1) whether the signals
intelligence collection the President determined was necessary to undertake is such
a core exercise of Commander in Chief control over the Armed Forces during
armed conflict that Congress cannot interfere with it at all and (2) whether the
particular restrictions imposed by FISA are such that their application would
impermissibly impede the President’s exercise of his constitutionally assigned
duties as Commander in Chief. Constitutional avoidance principles require

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interpreting FISA, at least in the context of the military conflict authorized by the
AUMF, to avoid these questions, if “fairly possible.” Even if Congress intended
FISA to use the full extent of its constitutional authority to “occupy the field” of
“electronic surveillance,” as FISA used that term, during peacetime, the legislative
history indicates that Congress had not reached a definitive conclusion about its
regulation during wartime. See H.R. Conf. Rep. No. 95-1720, at 34, reprinted in
1978 U.S.C.C.A.N. at 4063 (noting that the purpose of the fifteen-day period
following a declaration of war in section 111 of FISA was to “allow time for
consideration of any amendment to this act that may be appropriate during a
wartime emergency”). Therefore, it is not clear that Congress, in fact, intended
to test the limits of its constitutional authority in the context of wartime electronic
surveillance.
Whether Congress may interfere with the President’s constitutional authority to
collect foreign intelligence information through interception of communications
reasonably believed to be linked to the enemy poses a difficult constitutional
question. As explained in Part III.A, it had long been accepted at the time of
FISA’s enactment that the President has inherent constitutional authority to
conduct warrantless electronic surveillance for foreign intelligence purposes.
Congress recognized at the time that the enactment of a statute purporting to
eliminate the President’s ability, even during peacetime, to conduct warrantless
electronic surveillance to collect foreign intelligence was near or perhaps beyond
the limit of Congress’s Article I powers. The NSA activities, however, involve
signals intelligence performed in the midst of a congressionally authorized armed
conflict undertaken to prevent further hostile attacks on the United States. The
NSA activities lie at the very core of the Commander in Chief power, especially in
light of the AUMF’s explicit authorization for the President to take all necessary
and appropriate military action to stop al Qaeda from striking again. The constitu-
tional principles at stake here thus involve not merely the President’s well-
established inherent authority to conduct warrantless surveillance for foreign
intelligence purposes during peacetime, but also the powers and duties expressly
conferred on him as Commander in Chief by Article II.
Even outside the context of wartime surveillance of the enemy, the source and
scope of Congress’s power to restrict the President’s inherent authority to conduct
foreign intelligence surveillance is unclear. As explained above, the President’s
role as sole organ for the Nation in foreign affairs has long been recognized as
carrying with it preeminent authority in the field of national security and foreign
intelligence. The source of this authority traces to the Vesting Clause of Article II,
which states that “[t]he executive Power shall be vested in a President of the
United States of America.” U.S. Const. art. II, § 1. The Vesting Clause “has long
been held to confer on the President plenary authority to represent the United
States and to pursue its interests outside the borders of the country, subject only to
limits specifically set forth in the Constitution itself and to such statutory limita-
tions as the Constitution permits Congress to impose by exercising one of its

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enumerated powers.” The President’s Compliance With the “Timely Notification
“Requirement of Section 501(b) of the National Security Act, 10 Op. O.L.C. 159,
160–61 (1986) (“Timely Notification Requirement”).
Moreover, it is clear that some presidential authorities in this context are be-
yond Congress’s ability to regulate. For example, as the Supreme Court explained
in Curtiss-Wright, the President “makes treaties with the advice and consent of the
Senate; but he alone negotiates. Into the field of negotiation the Senate cannot
intrude; and Congress itself is powerless to invade it.” 299 U.S. at 319. Similarly,
President Washington established early in the history of the Republic the Execu-
tive’s absolute authority to maintain the secrecy of negotiations with foreign
powers, even against congressional efforts to secure information. See id. at 320–
21. Recognizing presidential authority in this field, the Executive Branch has taken
the position that “congressional legislation authorizing extraterritorial diplomatic
and intelligence activities is superfluous, and . . . statutes infringing the President’s
inherent Article II authority would be unconstitutional.” Timely Notification
Requirement, 10 Op. O.L.C. at 164.
There are certainly constitutional limits on Congress’s ability to interfere with
the President’s power to conduct foreign intelligence searches, consistent with the
Constitution, within the United States. As explained above, intelligence gathering
is at the heart of executive functions. Since the time of the Founding it has been
recognized that matters requiring secrecy—and intelligence in particular—are
quintessentially executive functions. See, e.g., The Federalist No. 64, at 435 (John
Jay) (Jacob E. Cooke ed. 1961) (“The convention have done well therefore in so
disposing of the power of making treaties, that although the president must in
forming them act by the advice and consent of the senate, yet he will be able to
manage the business of intelligence in such manner as prudence may suggest.”);
see also Timely Notification Requirement, 10 Op. O.L.C. at 165; cf. New York
Times Co. v. United States, 403 U.S. 713, 729–30 (1971) (Stewart, J., concurring)
(“[I]t is the constitutional duty of the Executive—as a matter of sovereign
prerogative and not as a matter of law as the courts know law—through the
promulgation and enforcement of executive regulations, to protect the confidenti-
ality necessary to carry out its responsibilities in the field of international relations
and national defense.”).
Because Congress has rarely attempted to intrude in this area and because many
of these questions are not susceptible to judicial review, there are few guideposts
for determining exactly where the line defining the President’s sphere of exclusive
authority lies. Typically, if a statute is in danger of encroaching upon exclusive
powers of the President, the courts apply the constitutional avoidance canon, if a
construction avoiding the constitutional issue is “fairly possible.” See, e.g., Egan,
484 U.S. at 527, 530. The only court that squarely has addressed the relative
powers of Congress and the President in this field suggested that the balance tips
decidedly in the President’s favor. The Foreign Intelligence Surveillance Court of

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 Legal Authorities Supporting the Activities of the National Security Agency

Review recently noted that all courts to have addressed the issue of the President’s
inherent authority have “held that the President did have inherent authority to
conduct warrantless searches to obtain foreign intelligence information.” In re
Sealed Case, 310 F.3d 717, 742 (FISA Ct. Rev. 2002). On the basis of that
unbroken line of precedent, the court “[took] for granted that the President does
have that authority,” and concluded that, “assuming that is so, FISA could not
encroach on the President’s constitutional power.” Id. 14 Although the court did not
provide extensive analysis, it is the only judicial statement on point, and it comes
from the specialized appellate court created expressly to deal with foreign
intelligence issues under FISA.
But the NSA activities are not simply exercises of the President’s general for-
eign affairs powers. Rather, they are primarily an exercise of the President’s
authority as Commander in Chief during an armed conflict that Congress expressly
has authorized the President to pursue. The NSA activities, moreover, have been
undertaken specifically to prevent a renewed attack at the hands of an enemy that
has already inflicted the single deadliest foreign attack in the Nation’s history. The
core of the Commander in Chief power is the authority to direct the Armed Forces
in conducting a military campaign. Thus, the Supreme Court has made clear that
the “President alone” is “constitutionally invested with the entire charge of hostile
operations.” Hamilton v. Dillin, 88 U.S. (21 Wall.) 73, 87 (1874); The Federalist
No. 74, at 500 (Alexander Hamilton). “As commander-in-chief, [the President] is
authorized to direct the movements of the naval and military forces placed by law
at his command, and to employ them in the manner he may deem most effectual to
harass and conquer and subdue the enemy.” Fleming v. Page, 50 U.S. (9 How.)
603, 615 (1850). As Chief Justice Chase explained in 1866, although Congress has
authority to legislate to support the prosecution of a war, Congress may not
“interfere[] with the command of the forces and the conduct of campaigns. That
power and duty belong to the President as commander-in-chief.” Ex parte
Milligan, 71 U.S. (4 Wall.) 2, 139 (1866) (Chase, C.J., concurring in judgment)
(emphasis added).
The Executive Branch uniformly has construed the Commander in Chief and
foreign affairs powers to grant the President authority that is beyond the ability of
Congress to regulate. In 1860, Attorney General Black concluded that an act of
Congress, if intended to constrain the President’s discretion in assigning duties to
an officer in the army, would be unconstitutional:

As commander-in-chief of the army it is your right to decide accord-
ing to your own judgment what officer shall perform any particular
duty, and as the supreme executive magistrate you have the power of

14
In the past, other courts have declined to express a view on that issue one way or the other. See,
e.g., Butenko, 494 F.2d at 601 (“We do not intimate, at this time, any view whatsoever as the proper
resolution of the possible clash of the constitutional powers of the President and Congress.”).

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appointment. Congress could not, if it would, take away from the
President, or in anywise diminish the authority conferred upon him
by the Constitution.

Memorial of Captain Meigs, 9 Op. Att’y Gen. 462, 468 (1860). Attorney General
Black went on to explain that, in his view, the statute involved there could
probably be read as simply providing “a recommendation” that the President could
decline to follow at his discretion. Id. at 469–70. 15
Supreme Court precedent does not support claims of congressional authority
over core military decisions during armed conflicts. In particular, the two deci-
sions of the Supreme Court that address a conflict between asserted wartime
powers of the Commander in Chief and congressional legislation and that resolve
the conflict in favor of Congress—Little v. Barreme, 6 U.S. (2 Cranch) 170
(1804), and Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579 (1952)—are
both distinguishable from the situation presented by the NSA activities in the
conflict with al Qaeda. Neither supports the constitutionality of the restrictions in
FISA as applied here.
Barreme involved a suit brought to recover a ship seized by an officer of the
U.S. Navy on the high seas during the so-called “Quasi War” with France in 1799.

15
Executive practice recognizes, consistent with the Constitution, some congressional control over
the Executive’s decisions concerning the Armed Forces. See, e.g., U.S. Const. art. I, § 8, cl. 12
(granting Congress power “to raise and support Armies”). But such examples have not involved
congressional attempts to regulate the actual conduct of a military campaign, and there is no
comparable textual support for such interference. For example, just before World War II, Attorney
General Robert Jackson concluded that the Neutrality Act prohibited President Roosevelt from selling
certain armed naval vessels and sending them to Great Britain. See Acquisition of Naval and Air Bases
in Exchange for Over-Age Destroyers, 39 Op. Att’y Gen. 484, 496 (1940). Jackson’s apparent
conclusion that Congress could control the President’s ability to transfer war material does not imply
acceptance of direct congressional regulation of the Commander in Chief’s control of the means and
methods of engaging the enemy in conflict. Similarly, in Youngstown Sheet & Tube Co. v. Sawyer, the
Truman Administration readily conceded that, if Congress had prohibited the seizure of steel mills by
statute, Congress’s action would have been controlling. See Brief for Petitioner at 150, Youngstown
Sheet & Tube Co. v. Sawyer, 343 U.S. 579 (1952) (Nos. 744 and 745). This concession implies nothing
concerning congressional control over the methods of engaging the enemy.
Likewise, the fact that the Executive Branch has, at times, sought congressional ratification after
taking unilateral action in a wartime emergency does not reflect a concession that the Executive lacks
authority in this area. A decision to seek congressional support can be prompted by many motivations,
including a desire for political support. In modern times, several administrations have sought
congressional authorization for the use of military force while preserving the ability to assert the
unconstitutionality of the War Powers Resolution. See, e.g., Statement on Signing the Resolution
Authorizing the Use of Military Force Against Iraq (Jan. 14, 1991), 1 Pub. Papers of Pres. George
Bush 40, 40 (1991) (“[M]y request for congressional support did not . . . constitute any change in the
long-standing positions of the executive branch on either the President’s constitutional authority to use
the Armed Forces to defend vital U.S. interests or the constitutionality of the War Powers Resolu-
tion.”). Moreover, many actions for which congressional support has been sought—such as President
Lincoln’s action in raising an army in 1861—quite likely fall primarily under Congress’s core Article I
powers.

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The seizure had been based upon the officer’s orders implementing an act of
Congress suspending commerce between the United States and France and
authorizing the seizure of American ships bound to a French port. The ship in
question was suspected of sailing from a French port. The Supreme Court held that
the orders given by the President could not authorize a seizure beyond the terms of
the statute and therefore that the seizure of the ship not in fact bound to a French
port was unlawful. 6 U.S. at 177–78. Although some commentators have broadly
characterized Barreme as standing for the proposition that Congress may restrict
by statute the means by which the President can direct the Nation’s Armed Forces
to carry on a war, the Court’s holding was limited in at least two significant ways.
First, the operative section of the statute in question applied only to American
merchant ships. See id. at 170 (quoting Act of February 9, 1799). Thus, the Court
simply had no occasion to rule on whether, even in the limited and peculiar
circumstances of the Quasi War, Congress could have placed some restriction on
the orders the Commander in Chief could issue concerning direct engagements
with enemy forces. Second, it is significant that the statute in Barreme was cast
expressly, not as a limitation on the conduct of warfare by the President, but rather
as regulation of a subject within the core of Congress’s enumerated powers under
Article I—the regulation of foreign commerce. See U.S. Const., art. I, § 8, cl. 3.
The basis of Congress’s authority to act was therefore clearer in Barreme than it is
here.
Youngstown involved an effort by the President—in the face of a threatened
work stoppage—to seize and to run steel mills. Congress had expressly considered
the possibility of giving the President power to effect such a seizure during
national emergencies. It rejected that option, however, instead providing different
mechanisms for resolving labor disputes and mechanisms for seizing industries to
ensure production vital to national defense.
For the Court, the connection between the seizure and the core Commander in
Chief function of commanding the Armed Forces was too attenuated. The Court
pointed out that the case did not involve authority over “day-to-day fighting in a
theater of war.” Id. at 587. Instead, it involved a dramatic extension of the
President’s authority over military operations to exercise control over an industry
that was vital for producing equipment needed overseas. Justice Jackson’s
concurring opinion also reveals a concern for what might be termed foreign-to-
domestic presidential bootstrapping. The United States became involved in the
Korean conflict through President Truman’s unilateral decision to commit troops
to the defense of South Korea. The President then claimed authority, based upon
this foreign conflict, to extend presidential control into vast sectors of the domestic
economy. Justice Jackson expressed “alarm[]” at a theory under which “a Presi-
dent whose conduct of foreign affairs is so largely uncontrolled, and often even is
unknown, can vastly enlarge his mastery over the internal affairs of the country by
his own commitment of the Nation’s armed forces to some foreign venture.” Id. at
642.

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Moreover, President Truman’s action extended the President’s authority into a
field that the Constitution predominantly assigns to Congress. See id. at 588
(discussing Congress’s commerce power and noting that “[t]he Constitution does
not subject this lawmaking power of Congress to presidential or military supervi-
sion or control”); see also id. at 643 (Jackson, J., concurring) (explaining that
Congress is given express authority to “‘raise and support Armies’” and “‘to
provide and maintain a Navy’”) (quoting U.S. Const. art. I, § 8, cls. 12, 13). Thus,
Youngstown involved an assertion of executive power that not only stretched far
beyond the President’s core Commander in Chief functions, but that did so by
intruding into areas where Congress had been given an express, and apparently
dominant, role by the Constitution. 16
The present situation differs dramatically. The exercise of executive authority
involved in the NSA activities is not several steps removed from the actual
conduct of a military campaign. As explained above, it is an essential part of the
military campaign. Unlike the activities at issue in Youngstown, the NSA activities
are directed at the enemy, and not at domestic activity that might incidentally aid
the war effort. And assertion of executive authority here does not involve extend-
ing presidential power into areas reserved for Congress. Moreover, the theme that
appeared most strongly in Justice Jackson’s concurrence in Youngstown—the fear
of presidential bootstrapping—does not apply in this context. Whereas President
Truman had used his inherent constitutional authority to commit U.S. troops, here
Congress expressly provided the President sweeping authority to use “all neces-
sary and appropriate force” to protect the Nation from further attack. AUMF
§ 2(a). There is thus no bootstrapping concern.
Finally, Youngstown cannot be read to suggest that the President’s authority for
engaging the enemy is less extensive inside the United States than abroad. To the
contrary, the extent of the President’s Commander in Chief authority necessarily
depends on where the enemy is found and where the battle is waged. In World
War II, for example, the Supreme Court recognized that the President’s authority
as Commander in Chief, as supplemented by Congress, included the power to
capture and try agents of the enemy in the United States, even if they never had
“entered the theatre or zone of active military operations.” Quirin, 317 U.S. at 38. 17

16
Youngstown does demonstrate that the mere fact that executive action might be placed in Justice
Jackson’s category III does not obviate the need for further analysis. Justice Jackson’s framework
therefore recognizes that Congress might impermissibly interfere with the President’s authority as
Commander in Chief or to conduct the Nation’s foreign affairs.
17
It had been recognized long before Youngstown that, in a large-scale conflict, the area of opera-
tions could readily extend to the continental United States, even when there are no major engagements
of armed forces here. Thus, in the context of the trial of a German officer for spying in World War I, it
was recognized that “[w]ith the progress made in obtaining ways and means for devastation and
destruction, the territory of the United States was certainly within the field of active operations” during
the war, particularly in the port of New York, and that a spy in the United States might easily have
aided the “hostile operation” of U-boats off the coast. United States ex reI. Wessels v. McDonald, 265
F. 754, 764 (E.D.N.Y. 1920).

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In the present conflict, unlike in the Korean War, the battlefield was brought to the
United States in the most literal way, and the United States continues to face a
threat of further attacks on its soil. In short, therefore, Youngstown does not
support the view that Congress may constitutionally prohibit the President from
authorizing the NSA activities.
The second serious constitutional question is whether the particular restrictions
imposed by FISA would impermissibly hamper the President’s exercise of his
constitutionally assigned duties as Commander in Chief. The President has
determined that the speed and agility required to carry out the NSA activities
successfully could not have been achieved under FISA. 18 Because the President
also has determined that the NSA activities are necessary to the defense of the
United States from a subsequent terrorist attack in the armed conflict with al
Qaeda, FISA would impermissibly interfere with the President’s most solemn
constitutional obligation—to defend the United States against foreign attack.
Indeed, if an interpretation of FISA that allows the President to conduct the
NSA activities were not “fairly possible,” FISA would be unconstitutional as
applied in the context of this congressionally authorized armed conflict. In that
event, FISA would purport to prohibit the President from undertaking actions
necessary to fulfill his constitutional obligation to protect the Nation from foreign
attack in the context of a congressionally authorized armed conflict with an enemy
that has already staged the most deadly foreign attack in our Nation’s history. A
statute may not “impede the President’s ability to perform his constitutional duty,”
Morrison v. Olson, 487 U.S. 654, 691 (1988) (emphasis added); see also id. at
696–97, particularly not the President’s most solemn constitutional obligation—
the defense of the Nation. See also In re Sealed Case, 310 F.3d at 742 (explaining
that “FISA could not encroach on the President’s constitutional power”).
Application of the avoidance canon would be especially appropriate here for
several reasons beyond the acute constitutional crises that would otherwise result.
First, as noted, Congress did not intend FISA to be the final word on electronic
surveillance conducted during armed conflicts. Instead, Congress expected that it
would revisit the subject in subsequent legislation. Whatever intent can be gleaned
from FISA’s text and legislative history to set forth a comprehensive scheme for
regulating electronic surveillance during peacetime, that same intent simply does
not extend to armed conflicts and declared wars. 19 Second, FISA was enacted
during the Cold War, not during active hostilities with an adversary whose mode
of operation is to blend in with the civilian population until it is ready to strike.

18
In order to avoid further compromising vital national security activities, a full explanation of the
basis for the President’s determination cannot be given in an unclassified document.
19
FISA exempts the President from its procedures for fifteen days following a congressional
declaration of war. See 50 U.S.C. § 1811. If an adversary succeeded in a decapitation strike, preventing
Congress from declaring war or passing subsequent authorizing legislation, it seems clear that FISA
could not constitutionally continue to apply in such circumstances.

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These changed circumstances have seriously altered the constitutional calculus,
one that FISA’s enactors had already recognized might suggest that the statute was
unconstitutional. Third, certain technological changes have rendered FISA still
more problematic. As discussed above, when FISA was enacted in 1978, Congress
expressly declined to regulate through FISA certain signals intelligence activities
conducted by the NSA. See supra Part III.C.1 & n.6. 20 These same factors weigh
heavily in favor of concluding that FISA would be unconstitutional as applied to
the current conflict if the canon of constitutional avoidance could not be used to
head off a collision between the branches.

*****

As explained above, FISA is best interpreted to allow a statute such as the
AUMF to authorize electronic surveillance outside FISA’s enumerated procedures.
The strongest counterarguments to this conclusion are that various provisions in
FISA and title 18, including section 111 of FISA and section 2511(2)(f) of title 18,
together require that subsequent legislation must reference or amend FISA in order
to authorize electronic surveillance outside FISA’s procedures and that interpret-
ing the AUMF as a statute authorizing electronic surveillance outside FISA
procedures amounts to a disfavored repeal by implication. At the very least,
however, interpreting FISA to allow a subsequent statute such as the AUMF to
authorize electronic surveillance without following FISA’s express procedures is
“fairly possible,” and that is all that is required for purposes of invoking constitu-
tional avoidance. In the competition of competing canons, particularly in the
context of an ongoing armed conflict, the constitutional avoidance canon carries
much greater interpretative force. 21

20
Since FISA’s enactment in 1978, the means of transmitting communications has undergone
extensive transformation. In particular, many communications that would have been carried by wire are
now transmitted through the air, and many communications that would have been carried by radio
signals (including by satellite transmissions) are now transmitted by fiber optic cables. It is such
technological advancements that have broadened FISA’s reach, not any particularized congressional
judgment that the NSA’s traditional activities in intercepting such international communications should
be subject to FISA’s procedures. A full explanation of these technological changes would require a
discussion of classified information.
21
If the text of FISA were clear that nothing other than an amendment to FISA could authorize
additional electronic surveillance, the AUMF would impliedly repeal as much of FISA as would
prevent the President from using “all necessary and appropriate force” in order to prevent al Qaeda and
its allies from launching another terrorist attack against the United States. To be sure, repeals by
implication are disfavored and are generally not found whenever two statutes are “capable of co-
existence.” Ruckelshaus v. Monsanto Co., 467 U.S. 986, 1018 (1984). Under this standard, an implied
repeal may be found where one statute would “unduly interfere with” the operation of another.
Radzanower v. Touche Ross & Co., 426 U.S. 148, 156 (1976). The President’s determination that
electronic surveillance of al Qaeda outside the confines of FISA was “necessary and appropriate”
would create a clear conflict between the AUMF and FISA. FISA’s restrictions on the use of electronic
surveillance would preclude the President from doing what the AUMF specifically authorized him to
do: use all “necessary and appropriate force” to prevent al Qaeda from carrying out future attacks

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 Legal Authorities Supporting the Activities of the National Security Agency

D. The NSA Activities Are Consistent With the Fourth Amendment

The Fourth Amendment prohibits “unreasonable searches and seizures” and
directs that “no Warrants shall issue, but upon probable cause, supported by Oath
or affirmation, and particularly describing the place to be searched, and the
persons or things to be seized.” U.S. Const. amend. IV. The touchstone for review
of government action under the Fourth Amendment is whether the search is
“reasonable.” See, e.g., Vernonia Sch. Dist. v. Acton, 515 U.S. 646, 653 (1995).
As noted above, see Part III.A, all of the federal courts of appeals to have ad-
dressed the issue have affirmed the President’s inherent constitutional authority to
collect foreign intelligence without a warrant. See In re Sealed Case, 310 F.3d at
742. Properly understood, foreign intelligence collection in general, and the NSA
activities in particular, fit within the “special needs” exception to the warrant
requirement of the Fourth Amendment. Accordingly, the mere fact that no warrant
is secured prior to the surveillance at issue in the NSA activities does not suffice to
render the activities unreasonable. Instead, reasonableness in this context must be
assessed under a general balancing approach, “‘by assessing, on the one hand, the
degree to which it intrudes upon an individual’s privacy and, on the other, the
degree to which it is needed for the promotion of legitimate governmental
interests.’” United States v. Knights, 534 U.S. 112, 118–19 (2001) (quoting Wyo-
ming v. Houghton, 526 U.S. 295, 300 (1999)). The NSA activities are reasonable
because the government’s interest, defending the Nation from another foreign
attack in time of armed conflict, outweighs the individual privacy interests at
stake, and because they seek to intercept only international communications where
one party is linked to al Qaeda or an affiliated terrorist organization.

against the United States. The ordinary restrictions in FISA cannot continue to apply if the AUMF is to
have its full effect; those constraints would “unduly interfere” with the operation of the AUMF.
Contrary to the recent suggestion made by several law professors and former government officials,
the ordinary presumption against implied repeals is overcome here. Cf. Letter for Bill Frist, Majority
Leader, U.S. Senate, from Curtis A. Bradley et al. at 4 (Jan. 9, 2006). First, like other canons of
statutory construction, the canon against implied repeals is simply a presumption that may be rebutted
by other factors, including conflicting canons. Conn. Nat’l Bank v. Germain, 503 U.S. 249, 253 (1992);
see also Chickasaw Nation v. United States, 534 U.S. 84, 94 (2001); Circuit City Stores, Inc. v. Adams,
532 U.S. 105, 115 (2001). Indeed, the Supreme Court has declined to apply the ordinary presumption
against implied repeals where other canons apply and suggest the opposite result. See Montana v.
Blackfeet Tribe of Indians, 471 U.S. 759, 765–66 (1985). Moreover, Blackfeet suggests that where the
presumption against implied repeals would conflict with other, more compelling interpretive
imperatives, it simply does not apply at all. See 471 U.S. at 766. Here, in light of the constitutional
avoidance canon, which imposes the overriding imperative to use the tools of statutory interpretation to
avoid constitutional conflicts, the implied repeal canon either would not apply at all or would apply
with significantly reduced force. Second, the AUMF was enacted during an acute national emergency,
where the type of deliberation and detail normally required for application of the canon against implied
repeals was neither practical nor warranted. As discussed above, in these circumstances, Congress
cannot be expected to work through every potential implication of the U.S. Code and to define with
particularity each of the traditional incidents of the use of force available to the President.

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1. The Warrant Requirement of the Fourth Amendment
Does Not Apply to the NSA Activities

In “the criminal context,” the Fourth Amendment reasonableness requirement
“usually requires a showing of probable cause” and a warrant. Bd. of Educ. v.
Earls, 536 U.S. 822, 828 (2002). The requirement of a warrant supported by
probable cause, however, is not universal. Rather, the Fourth Amendment’s
“central requirement is one of reasonableness,” and the rules the Court has
developed to implement that requirement “[s]ometimes . . . require warrants.”
Illinois v. McArthur, 531 U.S. 326, 330 (2001); see also, e.g., Earls, 536 U.S. at
828 (noting that the probable cause standard “is peculiarly related to criminal
investigations and may be unsuited to determining the reasonableness of adminis-
trative searches where the Government seeks to prevent the development of
hazardous conditions”) (internal quotation marks omitted).
In particular, the Supreme Court repeatedly has made clear that in situations
involving “special needs” that go beyond a routine interest in law enforcement, the
warrant requirement is inapplicable. See Vernonia, 515 U.S. at 653 (there are
circumstances “‘when special needs, beyond the normal need for law enforcement,
make the warrant and probable-cause requirement impracticable’”) (quoting
Griffin v. Wisconsin, 483 U.S. 868, 873 (1987)); see also McArthur, 531 U.S. at
330 (“When faced with special law enforcement needs, diminished expectations of
privacy, minimal intrusions, or the like, the Court has found that certain general, or
individual, circumstances may render a warrantless search or seizure reasonable.”).
It is difficult to encapsulate in a nutshell all of the different circumstances the
Court has found to qualify as “special needs” justifying warrantless searches. But
one application in which the Court has found the warrant requirement inapplicable
is in circumstances in which the government faces an increased need to be able to
react swiftly and flexibly, or when there are at stake interests in public safety
beyond the interests in ordinary law enforcement. One important factor in
establishing “special needs” is whether the government is responding to an
emergency that goes beyond the need for general crime control. See In re Sealed
Case, 310 F.3d at 745–46.
Thus, the Court has permitted warrantless searches of property of students in
public schools, see New Jersey v. T.L.O., 469 U.S. 325, 340 (1985) (noting that
warrant requirement would “unduly interfere with the maintenance of the swift
and informal disciplinary procedures needed in the schools”), to screen athletes
and students involved in extracurricular activities at public schools for drug use,
see Vernonia, 515 U.S. at 654–55; Earls, 536 U.S. at 829–38, to conduct drug
testing of railroad personnel involved in train accidents, see Skinner v. Ry. Labor
Execs.’ Ass’n, 489 U.S. 602, 634 (1989), and to search probationers’ homes, see
Griffin, 483 U.S. 868. Many special needs doctrine and related cases have upheld
suspicionless searches or seizures. See, e.g., Illinois v. Lidster, 540 U.S. 419, 427
(2004) (implicitly relying on special needs doctrine to uphold use of automobile

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checkpoint to obtain information about recent hit-and-run accident); Earls, 536
U.S. at 829–38 (suspicionless drug testing of public school students involved in
extracurricular activities); Mich. Dep’t of State Police v. Sitz, 496 U.S. 444, 449–
55 (1990) (road block to check all motorists for signs of drunken driving); United
States v. Martinez-Fuerte, 428 U.S. 543 (1976) (road block near the border to
check vehicles for illegal immigrants); cf. In re Sealed Case, 310 F.3d at 745–46
(noting that suspicionless searches and seizures in one sense are a greater en-
croachment on privacy than electronic surveillance under FISA because they are
not based on any particular suspicion, but “[o]n the other hand, wiretapping is a
good deal more intrusive than an automobile stop accompanied by questioning”).
To fall within the “special needs” exception to the warrant requirement, the
purpose of the search must be distinguishable from ordinary general crime control.
See, e.g., Ferguson v. Charleston, 532 U.S. 67 (2001); City of Indianapolis v.
Edmond, 531 U.S. 32, 41 (2000).
Foreign intelligence collection, especially in the midst of an armed conflict in
which the adversary has already launched catastrophic attacks within the United
States, fits squarely within the area of “special needs, beyond the normal need for
law enforcement,” where the Fourth Amendment’s touchstone of reasonableness
can be satisfied without resort to a warrant. Vernonia, 515 U.S. at 653. The
Executive Branch has long maintained that collecting foreign intelligence is far
removed from the ordinary criminal law enforcement action to which the warrant
requirement is particularly suited. See, e.g., Amending the Foreign Intelligence
Surveillance Act: Hearings Before the H. Permanent Select Comm. on Intelli-
gence, 103d Cong. 62, 63 (1994) (statement of Deputy Attorney General Jamie S.
Gorelick) (“[I]t is important to understand that the rules and methodology for
criminal searches are inconsistent with the collection of foreign intelligence and
would unduly frustrate the President in carrying out his foreign intelligence
responsibilities. . . . [W]e believe that the warrant clause of the Fourth Amendment
is inapplicable to such [foreign intelligence] searches.”); see also In re Sealed
Case, 310 F.3d at 745. The object of foreign intelligence collection is securing
information necessary to protect the national security from the hostile designs of
foreign powers like al Qaeda and affiliated terrorist organizations, including the
possibility of another foreign attack on the United States. In foreign intelligence
investigations, moreover, the targets of surveillance often are agents of foreign
powers, including international terrorist groups, who may be specially trained in
concealing their activities and whose activities may be particularly difficult to
detect. The Executive requires a greater degree of flexibility in this field to
respond with speed and absolute secrecy to the ever-changing array of foreign
threats faced by the Nation. 22

22
Even in the domestic context, the Supreme Court has recognized that there may be significant
distinctions between wiretapping for ordinary law enforcement purposes and domestic national security
surveillance. See United States v. U.S. Dist. Ct., 407 U.S. 297, 322 (1972) (“Keith”) (explaining that

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In particular, the NSA activities are undertaken to prevent further devastating
attacks on our Nation, and they serve the highest government purpose through
means other than traditional law enforcement. 23 The NSA activities are designed to
enable the government to act quickly and flexibly (and with secrecy) to find agents
of al Qaeda and its affiliates—an international terrorist group which has already
demonstrated a capability to infiltrate American communities without being
detected—in time to disrupt future terrorist attacks against the United States. As
explained by the Foreign Intelligence Surveillance Court of Review, the nature of
the “emergency” posed by al Qaeda “takes the matter out of the realm of ordinary
crime control.” In re Sealed Case, 310 F.3d at 746. Thus, under the “special
needs” doctrine, no warrant is required by the Fourth Amendment for the NSA
activities.

2. The NSA Activities Are Reasonable

As the Supreme Court has emphasized repeatedly, “[t]he touchstone of the
Fourth Amendment is reasonableness, and the reasonableness of a search is
determined by assessing, on the one hand, the degree to which it intrudes upon an
individual’s privacy and, on the other, the degree to which it is needed for the
promotion of legitimate governmental interests.” Knights, 534 U.S. at 118–19
(quotation marks omitted); see also Earls, 536 U.S. at 829. The Supreme Court
has found a search reasonable when, under the totality of the circumstances, the
importance of the governmental interests outweighs the nature and quality of the
intrusion on the individual’s Fourth Amendment interests. See Knights, 534 U.S. at
118–22. Under the standard balancing of interests analysis used for gauging
reasonableness, the NSA activities are consistent with the Fourth Amendment.

“the focus of domestic [security] surveillance may be less precise than that directed against more
conventional types of crime” because often “the emphasis of domestic intelligence gathering is on the
prevention of unlawful activity or the enhancement of the Government’s preparedness for some
possible future crisis or emergency”); see also United States v. Duggan, 743 F.2d 59, 72 (2d Cir. 1984)
(reading Keith to recognize that “the governmental interests presented in national security investiga-
tions differ substantially from those presented in traditional criminal investigations”). Although the
Court in Keith held that the Fourth Amendment’s warrant requirement does apply to investigations of
purely domestic threats to national security—such as domestic terrorism, it suggested that Congress
consider establishing a lower standard for such warrants than that set forth in Title III. See id. at 322–23
(advising that “different standards” from those applied to traditional law enforcement “may be compati-
ble with the Fourth Amendment if they are reasonable both in relation to the legitimate need of the
Government for intelligence information and the protected rights of our citizens”). Keith’s emphasis on
the need for flexibility applies with even greater force to surveillance directed at foreign threats to
national security. See S. Rep. No. 95-701, at 16 (“Far more than in domestic security matters, foreign
counterintelligence investigations are ‘long range’ and involve ‘the interrelation of various sources and
types of information.’”) (quoting Keith, 407 U.S. at 322). And flexibility is particularly essential here,
where the purpose of the NSA activities is to prevent another armed attack against the United States.
23
This is not to say that traditional law enforcement has no role in protecting the Nation from
attack. The NSA activities, however, are not directed at bringing criminals to justice but at detecting
and preventing plots by a declared enemy of the United States to attack it again.

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With respect to the individual privacy interests at stake, there can be no doubt
that, as a general matter, interception of telephone communications implicates a
significant privacy interest of the individual whose conversation is intercepted.
The Supreme Court has made clear at least since Katz v. United States, 389 U.S.
347 (1967), that individuals have a substantial and constitutionally protected
reasonable expectation of privacy that their telephone conversations will not be
subject to governmental eavesdropping. Although the individual privacy interests
at stake may be substantial, it is well recognized that a variety of governmental
interests—including routine law enforcement and foreign-intelligence gathering—
can overcome those interests.
On the other side of the scale here, the government’s interest in engaging in the
NSA activities is the most compelling interest possible—securing the Nation from
foreign attack in the midst of an armed conflict. One attack already has taken
thousands of lives and placed the Nation in state of armed conflict. Defending the
Nation from attack is perhaps the most important function of the federal govern-
ment—and one of the few express obligations of the federal government enshrined
in the Constitution. See U.S. Const. art. IV, § 4 (“The United States shall guaran-
tee to every State in this Union a Republican Form of Government, and shall
protect each of them against Invasion . . . .”) (emphasis added); The Prize Cases,
67 U.S. (2 Black) 635, 668 (1863) (“If war be made by invasion of a foreign
nation, the President is not only authorized but bound to resist force by force.”).
As the Supreme Court has declared, “[i]t is ‘obvious and unarguable’ that no
governmental interest is more compelling than the security of the Nation.” Haig v.
Agee, 453 U.S. 280, 307 (1981).
The government’s overwhelming interest in detecting and thwarting further al
Qaeda attacks is easily sufficient to make reasonable the intrusion into privacy
involved in intercepting one-end foreign communications where there is “a reasona-
ble basis to conclude that one party to the communication is a member of al Qaeda,
affiliated with al Qaeda, or a member of an organization affiliated with al Qaeda.”
Press Briefing by Attorney General Alberto Gonzales and General Michael
Hayden, Principal Deputy Director for National Intelligence (Dec. 19, 2005)
(statement of Attorney General Gonzales) (available at http://georgewbush-
whitehouse.archives.gov/news/releases/2005/12/20051219-1.html, last visited
Aug. 12, 2014); cf. Edmond, 531 U.S. at 44 (noting that “the Fourth Amendment
would almost certainly permit an appropriately tailored roadblock set up to thwart an
imminent terrorist attack” because “[t]he exigencies created by th[at] scenario[] are
far removed” from ordinary law enforcement). The United States has already
suffered one attack that killed thousands, disrupted the Nation’s financial center for
days, and successfully struck at the command and control center for the Nation’s
military. And the President has stated that the NSA activities are “critical” to our
national security. President’s News Conference, 41 Weekly Comp. Pres. Doc. at
1886. To this day, finding al Qaeda sleeper agents in the United States remains one
of the preeminent concerns of the war on terrorism. As the President has explained,

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“[t]he terrorists want to strike America again, and they hope to inflict even more
damage than they did on September 11th.” Id.
Of course, because the magnitude of the government’s interest here depends in
part upon the threat posed by al Qaeda, it might be possible for the weight that
interest carries in the balance to change over time. It is thus significant for the
reasonableness of the NSA activities that the President has established a system
under which he authorizes the surveillance only for a limited period, typically for
45 days. This process of reauthorization ensures a periodic review to evaluate
whether the threat from al Qaeda remains sufficiently strong that the government’s
interest in protecting the Nation and its citizens from foreign attack continues to
outweigh the individual privacy interests at stake.
Finally, as part of the balancing of interests to evaluate Fourth Amendment
reasonableness, it is significant that the NSA activities are limited to intercepting
international communications where there is a reasonable basis to conclude that
one party to the communication is a member or agent of al Qaeda or an affiliated
terrorist organization. This factor is relevant because the Supreme Court has
indicated that in evaluating reasonableness, one should consider the “efficacy of
[the] means for addressing the problem.” Vernonia, 515 U.S. at 663; see also
Earls, 536 U.S. at 834 (“Finally, this Court must consider the nature and immedia-
cy of the government’s concerns and the efficacy of the Policy in meeting them.”).
That consideration does not mean that reasonableness requires the “least intrusive”
or most “narrowly tailored” means for obtaining information. To the contrary, the
Supreme Court has repeatedly rejected such suggestions. See, e.g., Earls, 536 U.S.
at 837 (“[T]his Court has repeatedly stated that reasonableness under the Fourth
Amendment does not require employing the least intrusive means, because the
logic of such elaborate less-restrictive-alternative arguments could raise insupera-
ble barriers to the exercise of virtually all search-and-seizure powers.”) (internal
quotation marks omitted); Vernonia, 515 U.S. at 663 (“We have repeatedly re-
fused to declare that only the ‘least intrusive’ search practicable can be reasonable
under the Fourth Amendment.”). Nevertheless, the Court has indicated that some
consideration of the efficacy of the search being implemented—that is, some
measure of fit between the search and the desired objective—is relevant to the
reasonableness analysis. The NSA activities are targeted to intercept international
communications of persons reasonably believed to be members or agents of al
Qaeda or an affiliated terrorist organization, a limitation which further strongly
supports the reasonableness of the searches.
In sum, the NSA activities are consistent with the Fourth Amendment because
the warrant requirement does not apply in these circumstances, which involve both
“special needs” beyond the need for ordinary law enforcement and the inherent
authority of the President to conduct warrantless electronic surveillance to obtain
foreign intelligence to protect our Nation from foreign armed attack. The touch-
stone of the Fourth Amendment is reasonableness, and the NSA activities are

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certainly reasonable, particularly taking into account the nature of the threat the
Nation faces.

IV. Conclusion

For the foregoing reasons, the President—in light of the broad authority to use
military force in response to the attacks of September 11th and to prevent further
catastrophic attack expressly conferred on the President by the Constitution and
confirmed and supplemented by Congress in the AUMF—has legal authority to
authorize the NSA to conduct the signals intelligence activities he has described.
Those activities are authorized by the Constitution and by statute, and they violate
neither FISA nor the Fourth Amendment.

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