The President and the War Power: South Vietnam and the Cambodian Sanctuaries

The President and the War Power:
South Vietnam and the Cambodian Sanctuaries
Recognizing congressional sanction for the Vietnam conflict by the Gulf of Tonkin resolution, even
though it was not in name or by its terms a formal declaration of war, the President’s determination
to authorize incursion into the Cambodian border area by United States forces in order to destroy
sanctuaries utilized by the enemy is the sort of tactical decision traditionally confided to the Com-
mander in Chief in the conduct of armed conflict.
Only if the constitutional designation of the President as Commander in Chief conferred no substantive
authority whatever could it be said that prior congressional authorization for such a tactical decision
was required. Since even those authorities least inclined to a broad construction of the executive
power concede that the Commander in Chief provision does confer substantive authority over the
manner in which hostilities are conducted, the President’s decision to invade and destroy the border
sanctuaries in Cambodia was authorized under even a narrow reading of his power as Commander in
Chief.

May 22, 1970

MEMORANDUM OPINION FOR THE SPECIAL COUNSEL TO THE PRESIDENT*

The recent decision by President Nixon to use United States armed forces to
attack sanctuaries employed by the North Vietnamese and the Viet Cong which
were located across the Cambodian border from South Vietnam has raised the
issue of the scope for the President’s power to conduct military operations such as
those now underway in Southeast Asia. This memorandum addresses itself to that
issue.

I. Division of the War Power by the Framers of the Constitution

The draftsmen of the Constitution clearly intended to divide the war power
inhering in any sovereign nation between the President and Congress, and just as
clearly did not intend to precisely delimit the boundary between the power of the
Executive Branch and that of the Legislative Branch. They rejected the traditional
power of kings to commit unwilling nations to war to further the king’s interna-
tional political objectives. At the same time, they recognized the need for quick
executive response to rapidly developing international situations.
The accommodation of these two interests took place in the session of the
Constitutional Convention on Friday, August 17, 1787. The enumeration of the
powers of Congress was in the process of being submitted to the delegates, and
discussion occurred following the submission to vote of the draft language
empowering Congress “to make war.”

*
Editor’s Note: This memorandum was addressed to Charles W. Colson, Special Counsel to the
President. The cover memorandum explained as follows: “Enclosed is an expanded version of the
memorandum on Presidential power entitled The President and the War Power: South Vietnam and the
Cambodian Sanctuaries. I am sending copies to Jack Stevenson and John Lehman.”

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The full text of the discussion, as reflected in Madison’s notes of the proceed-
ings, is set forth as an appendix to this memorandum. * The upshot was that the
authority conferred upon Congress was changed from the power “to make war” to
the power “to declare war.” 3 The Papers of James Madison 1351–53 (Henry D.
Gilpin ed., 1841) (“Madison Notes”). Charles Pinckney urged that the war-making
power be confided to the Senate alone, id. at 1351, while Pierce Butler urged that
the power be vested in the President, id. at 1352. James Madison and Elbridge
Gerry then jointly moved to substitute the word “declare” for the word “make,”
“leaving to the Executive the power to repel sudden attacks.” Id. John Sherman
expressed a preference for “make” as opposed to “declare,” because the latter was
too narrow a grant of power. However, he expressed the view that the grant of
power to Congress to “make” war would nonetheless permit the Executive to repel
attack, although not to commence war. Id. Gerry and George Mason opposed the
giving of the power to declare war to the Executive. Id. Rufus King supported the
substitution of the word “declare,” urging that the word “make” might be under-
stood to mean “conduct” war, which latter was an executive function. Id. at 1353
n.*.
With only New Hampshire dissenting, it was agreed that the grant to Congress
should be of the power to declare war. Pinckney’s motion to strike out the whole
clause, and thereby presumably to leave the way open to vest the entire war-
making power in the Executive, was then defeated by a voice vote. Id. at 1353.
The framers of the Constitution, in making this division of authority between
the Executive and the Legislative Branches, were painting with a broad brush on a
constitutional fabric, and not endeavoring to accomplish a detailed allocation of
authority between the two branches. Nearly 200 years of practice under the
constitutional system has given rise to a number of precedents and usages,
although it cannot be confidently said that any sharp line of demarcation exists as
a result of this history.

II. Recognition of Armed Conflict Short of “War”

Before turning to historical practice for the light which it throws upon the
proper interpretation of the President’s power, it is well to first dispel any notion
that the United States may lawfully engage in armed hostilities with a foreign
power only if Congress has declared war. From the earliest days of the republic,
all three branches of the federal government have recognized that this is not so,
and that not every armed conflict between forces of two sovereigns is “war.” This
fact affords no final answer to the constitutional question of the division of
authority between the President and Congress in exercising the war power, but it

*
Editor’s Note: That appendix was not preserved in the OLC daybooks and so it is not included
here. Instead we have inserted citations to the appropriate parts of Madison’s notes on the Constitution-
al Convention.

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does suggest that the effort to find an answer is not advanced by a mechanical
application of labels to various fact situations.
Congress, during the so-called “undeclared war” with France which lasted from
1798 to 1800, authorized limited use of this nation’s armed forces against those of
France. The Fifth Congress authorized President Adams to take the following
measures:
That the President of the United States shall be, and is hereby author-
ized to instruct the commanders of the public armed vessels which
are, or which shall be employed in the service of the United States,
to subdue, seize and take any armed French vessel, which shall be
found within the jurisdictional limits of the United States, or else-
where, on the high seas, and such captured vessel, with her apparel,
guns and appurtenances, and the goods or effects which shall be
found on board the same, being French property shall be brought
within some port of the United States, and shall be duly proceeded
against and condemned as forfeited . . . .

Act of July 9, 1798, ch. 68, § 1, 1 Stat. 578, 578.
The Supreme Court in a case arising out of this “undeclared war” described
these differences between war and other armed conflicts as being differences
between “solemn war” and “imperfect war”:
If it be declared in form, it is called solemn, and is of the perfect
kind; because one whole nation is at war with another whole nation;
and all the members of the nation declaring war, are authorized to
commit hostilities against all the members of the other, in every
place, and under every circumstance. In such a war all the members
act under a general authority, and all the rights and consequences of
war attach to their condition.
But hostilities may subsist between two nations more confined in
its nature and extent; being limited as to places, persons, and things;
and this is more properly termed imperfect war; because not solemn,
and because those who are authorized to commit hostilities, act un-
der special authority, and can go no farther than to the extent of their
commission.
Bas v. Tingy (The Eliza), 4 U.S. (4 Dall.) 37, 40 (1800) (opinion of Washington,
J.).
While the Court termed both forms of military action “war,” the distinction
which it drew likewise separates the declared wars of the Twentieth Century, such
as the two World Wars, and the undeclared armed conflicts such as have more
recently occurred in Korea and in Southeast Asia. In both of the two World Wars,
the declarations of war were viewed by the Executive Branch to authorize

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complete subjugation of the enemy, and some form of “unconditional surrender”
on the part of the enemy was the announced goal of the allied nations. In Korea
and Vietnam, on the other hand, the goals have been the far more limited ones of
the maintenance of territorial integrity and of the right of self-determination.
As has been chronicled many times, the United States throughout its history has
been involved in armed conflicts short of declared war, from the undeclared war
with France in 1798–1800 to Vietnam. See, e.g., H.R. Rep. No. 82-127 (1951);
H.R. Doc. No. 84-443 (1956); James Grafton Rogers, World Policing and the
Constitution 92–123 (1945). The more significant of these involvements are
separately discussed in a following section of this memorandum.

III. Designation of the President as Commander in Chief Is a
Grant of Substantive Power

Because of the nature of the President’s power as Commander in Chief and
because of the fact that it is frequently exercised in external affairs, there are few
judicial precedents dealing with the subject. Such judicial learning as there is on
the subject, however, makes it reasonably clear that the designation of the
President as Commander in Chief of the Armed Forces is a substantive grant of
power, and not merely a commission which entitles him to precedence in a
reviewing stand.1
Chief Justice Marshall, writing for the Supreme Court in Little v. Barreme,
concluded that the seizure of a ship on the high seas had not been authorized by an
act of Congress. In the course of the opinion, he stated:
It is by no means clear that the President of the United States
whose high duty it is to “take care that the laws be faithfully execut-
ed,” and who is Commander in Chief of the armies and navies of the
United States, might not, without any special authority for that pur-
pose, in the then existing state of things, have empowered the offic-
ers commanding the armed vessels of the United States, to seize and

1
A statement of Alexander Hamilton in The Federalist 69 has been quoted in support of the notion
that the designation of the President as Commander in Chief does nothing more than place him at the
head of the military establishment. The full text of Hamilton’s comment does not support such a
narrow construction:
The President is to be Commander-in-Chief of the army and navy of the United States.
In this respect his authority would be nominally the same as that of the King of Great
Britain, but in substance much inferior to it. It would amount to nothing more than the
supreme command and direction of the military and naval forces, as first general and
admiral of the Confederacy; while that of the British king extends to the declaring of
war and to the raising and regulating of fleets and armies—all which, by the Constitu-
tion under consideration, would appertain to the Legislature.
The Federalist No. 69, at 417–18 (Clinton Rossiter ed., 1961).

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send into port for adjudication, American vessels which were forfeit-
ed by being engaged in this illicit commerce.
6 U.S. (2 Cranch) 170, 177 (1804).
Justice Grier, speaking for the Supreme Court in its famous decision in the
Prize Cases, likewise viewed the President’s designation as Commander in Chief
as being a substantive source of authority on which he might rely in putting down
rebellion:
Whether the President in fulfilling his duties, as Commander in
Chief, in suppressing an insurrection, has met with such armed hos-
tile resistance, and a civil war of such alarming proportions as will
compel him to accord to them the character of belligerents, is a ques-
tion to be decided by him, and this Court must be governed by the
decisions and acts of the political department of the Government to
which this power was entrusted. “He must determine what degree of
force the crisis demands.” The proclamation of blockade is itself of-
ficial and conclusive evidence to the Court that a state of war existed
which demanded and authorized a recourse to such a measure, under
the circumstances peculiar to the case.
67 U.S. (2 Black) 635, 670 (1862).
More recently, Justice Jackson, concurring in Youngstown Sheet & Tube Co. v.
Sawyer, said:
We should not use this occasion to circumscribe, much less to
contract, the lawful role of the President as Commander in Chief.
I should indulge the widest latitude of interpretation to sustain his
exclusive function to command the instruments of national force, at
least when turned against the outside world for the security of our
society.
343 U.S. 579, 646 (1952).
The limits of the President’s power as Commander in Chief are nowhere de-
fined in the Constitution, except by way of negative implication from the fact that
the power to declare war is committed to Congress. However, as a result of
numerous occurrences in the history of the Republic, more light has been thrown
on the scope of this power.

IV. Scope of President’s Power as Commander in Chief

The questions of how far the Chief Executive may go without congressional
authorization in committing American military forces to armed conflict, or in
deploying them outside of the United States and in conducting armed conflict
already authorized by Congress, have arisen repeatedly throughout the Nation’s

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history. The Executive has asserted and exercised at least three different varieties
of authority under his power as Commander in Chief:
(a) Authority to commit military forces of the United States to armed
conflict, at least in response to enemy attack or to protect the lives of
American troops in the field;
(b) Authority of deploy United States troops throughout the world,
both to fulfill United States treaty obligations and to protect Ameri-
can interests; and
(c) Authority to conduct or carry on armed conflict once it is institut-
ed, by making and carrying out the necessary strategic and tactical
decisions in connection with such conflict.
Congress has on some of these occasions acquiesced in the President’s action
without formal ratification; on others it has ratified the President’s action; and on
still others it has taken no action at all. On several of the occasions, individual
members of Congress, and, at the close of the Mexican War, one house of
Congress on a preliminary vote, have protested executive use of the armed forces.
While a particular course of executive conduct to which there was no opportunity
for the Legislative Branch to effectively object cannot establish a constitutional
precedent in the same manner as it would be established by an authoritative
judicial decision, a long continued practice on the part of the Executive, acqui-
esced in by the Congress, is itself some evidence of the existence of constitutional
authority to support such a practice. United States v. Midwest Oil Co., 236 U.S.
459 (1915). As stated by Justice Frankfurter in his concurring opinion in Youngs-
town Sheet & Tube:
The Constitution is a framework for government. Therefore the way
the framework has consistently operated fairly establishes that it has
operated according to its true nature. Deeply embedded traditional
ways of conducting government cannot supplant the Constitution or
legislation, but they give meaning to the words of a text or supply
them.

343 U.S. at 610.

A. Commitment of Military Forces to Armed Conflict Without
Congressional Authorization

President Jefferson, in 1801, sent a small squadron of American naval vessels
into the Mediterranean to protect United States commerce against threatened
attack by the Barbary pirates of Tripoli. In his message to Congress discussing his

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action, Jefferson took the view that it would require congressional authorization
for this squadron to assume an offensive, rather than a defensive, stance.
In May 1845, President Polk ordered military forces to the coasts of Mexico
and to the western frontier of Texas (still at that time an independent republic) in
order to prevent any interference by Mexico with the proposed annexation of
Texas to the United States. Following annexation, Polk ordered General Zachary
Taylor to march from the Nueces River, which Mexico claimed was the southern
border of Texas, to the Rio Grande River, which Texas claimed was the southern
boundary of Texas. While so engaged, Taylor’s forces encountered Mexican
troops, and hostilities between the two nations commenced on April 25, 1846.
While Polk two and a half weeks later requested a declaration of war from
Congress, there had been no prior authorization for Taylor’s march south of the
Nueces.
Justice Grier, in his opinion for the Supreme Court in the Prize Cases, com-
mented on this fact, stating:
The battles of Palo Alto and Rasaca de la Palma had been fought
before the passage of the act of Congress of May 13, 1846, which
recognized “a state of war as existing by the act of the Republic of
Mexico.”
67 U.S. at 668.
In 1854, President Pierce approved the action of a naval officer who bombard-
ed Greytown, Nicaragua, in retaliation against a revolutionary government that re-
fused to make reparations for damage and violence to United States citizens. This
action was upheld by Samuel Nelson, then a judge of the Southern District of New
York and later a Justice of the Supreme Court of the United States, in Durand v.
Hollins, 8 F. Case. 111 (C.C.D.N.Y. 1860) (No. 4186). In his opinion in that case,
Judge Nelson said:
As the executive head of the nation, the president is made the on-
ly legitimate organ of the general government, to open and carry on
correspondence of negotiations with foreign nations, in matters con-
cerning the interests of the country or of its citizens. It is to him, al-
so, the citizens abroad must look for protection of person and of
property, and for the faithful execution of the laws existing and
intended for their protection. For this purpose, the whole executive
power of the country is placed in his hands, under the constitution,
and the laws passed in pursuance thereof. . . .
. . . Acts of lawless violence, or of threatened violence to the citi-
zen or his property, cannot be anticipated and provided for; and for
the protection, to be effectual or of any avail, may, not unfrequently,
require the most prompt and decided action. . . .

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. . . The question whether it was the duty of the president to inter-
pose for the protection of the citizens at Greytown against an irre-
sponsible and marauding community that had established itself there,
was a public political question, in which the government, as well as
the citizens whose interests were involved, was concerned, and
which belonged to the executive to determine; and his decision is fi-
nal and conclusive, and justified the defendant in the execution of his
orders given through the Secretary of the Navy.
Id. at 112.
In April 1861, President Lincoln called for 75,000 volunteers to suppress the
rebellion by the southern states, and proclaimed a blockade of the Confederacy.
The Supreme Court in the Prize Cases upheld the acts taken by President Lincoln
prior to their later ratification by Congress in July 1861, saying:
If a war be made by invasion of a foreign nation, the President is
not only authorized but bound to resist force by force. He does not
initiate the war, but is bound to accept the challenge without waiting
for any special legislative authority.
67 U.S. at 668.
In 1900 President McKinley sent an expedition of 5,000 United States troops as
a component of an international force during the Boxer Rebellion of China. While
Congress recognized the existence of the conflict by providing for combat pay,
Act of Mar. 2, 1901, ch. 803, 31 Stat. 895, 903, it neither declared war nor
formally ratified the President’s action. A federal court, however, reiterated the
early recognition of limited or undeclared war:
In the present case, at no time was there any formal declaration of
war by the political department of this government against either the
government of China or the ‘Boxer’ element of that government. A
formal declaration of war, however, is unnecessary to constitute a
condition of war.

Hamilton v. McClaughry, 136 F. 445, 449 (C.C.D. Kan. 1905).
Presidents Theodore Roosevelt, Taft, and Wilson on more than one occasion
committed American troops abroad to protect American interests. In November
1903, President Roosevelt ordered the United States Navy to guard the Panama
area and prevent Colombian troops from being landed in Panama in order to
suppress the Panamanian insurrection against Colombia. In his annual report to
Congress in 1912, President Taft reported the sending of some 2,000 Marines to
Nicaragua (at the request of the President of Nicaragua) and the use of warships
and troops in Cuba. H.R. Doc. No. 62-927, at 8–9, 21 (1912). He merely advised
Congress of these actions without requesting any statutory authorization.

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President Wilson on two separate occasions committed American armed forces
to hostile actions in Mexican territory. In April 1914, he directed a force of sailors
and Marines to occupy the City of Vera Cruz, during the revolution in that
country. The city was seized and occupied for seven months without congressional
authorization. In 1916, Wilson ordered General Pershing and more than 10,000
troops to pursue Pancho Villa, the Mexican outlaw, into Mexican territory
following the latter’s raid on Columbus, New Mexico.
The most recent example of presidential combat use of American armed forces
without congressional declaration of war, prior to the Vietnam conflict, was
President Truman’s intervention in the Korean conflict. Following invasion of
South Korea by North Koreans on June 25, 1950, and a request for aid by the
United Nations (“UN”) Security Council (S.C. Res. 83, U.N. Doc. S/RES/83 (June
27, 1950)), President Truman ordered the United States air and sea forces to give
South Korean troops cover and support. He ordered the Seventh Fleet to guard
Formosa. On June 30, the President announced that he had authorized the use of
United States ground forces in the Korean War, following the collapse of the
South Korean Army. Ultimately, the number of troops engaged in the Korean
conflict reached 250,000, and the conflict lasted more than three years. President
Truman’s action without congressional authorization precipitated the “Great
Debate” in Congress which raged from January to April 1951.
While the President relied upon the UN Charter as a basis for his action, as well
as his power as Commander in Chief, his action stands as a precedent for execu-
tive action in committing United States armed forces to extensive hostilities
without any formal declaration of war by Congress.
The UN Charter as a result of its ratification by the Senate has the status of a
treaty, but it does not by virtue of this fact override any constitutional provision.
Though treaties made in pursuance of the Constitution under the Supremacy
Clause may override a state statute, Missouri v. Holland, 252 U.S. 416 (1920),
they may not override specific constitutional limitations, Geofroy v. Riggs, 133
U.S. 258 (1890); Reid v. Covert, 354 U.S. 1 (1957). If a congressional declaration
of war would be required in other circumstances to commit United States forces to
hostilities of the extent and nature of those undertaken in Korea, the ratification of
the UN Charter would not obviate a like requirement in the case of the Korean
conflict. While the issue of presidential power which was the subject of the great
debate in Congress was never authoritatively resolved, it is clear that Congress
acquiesced in President Truman’s intervention in Korea. See David Rees, Korea:
The Limited War (1964); Merlo J. Pusey, The Way We Go to War (1969).

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B. Deployment of United States Troops Throughout the World 2

In February 1917, President Wilson requested from Congress authority to arm
American merchant vessels. When that authority failed of passage in Congress as
a result of a filibuster, Wilson proceeded to arm them without congressional
authority, stating that he was relying on his authority as Commander in Chief.
Near the close of the First World War, President Wilson announced a decision
to send American troops to Siberia. The troops so sent remained for over a year,
with their withdrawal beginning in January, 1920. There was no congressional
authorization for such disposition of troops, and the United States had not declared
war on Russia.
In 1941, prior to Pearl Harbor, President Roosevelt utilized his power as Com-
mander in Chief to undertake a series of actions short of war designed to aid the
allied forces in the Second World War. On April 9, 1941, he made an agreement
with the Danish Minister for the occupation of Greenland by American forces. In
May 1941, Roosevelt issued a proclamation declaring an unlimited national
emergency, and he ordered American naval craft to “sink on sight” foreign
submarines found in the “defensive waters” of the United States. In July 1941, the
President announced that United States forces would occupy Iceland in order to
relieve British forces there, and that the Navy would perform convoy duty for
supplies being sent to Great Britain under Lend-Lease. In September 1941,
Roosevelt stated that he had given orders to the United States Army and Navy to
strike first at any German or Italian vessels of war in American “defensive
waters”; the following month, he decided to carry 20,000 British troops from
Halifax to the Middle East in American transports.
President Truman’s decision in 1951 to send four United States divisions to
Europe in discharge of the nation’s NATO commitment occasioned prolonged
debate in Congress over his powers to take such action without congressional
approval. Congress ultimately acquiesced in the President’s action without
actually resolving the question, and all of President Truman’s successors have
asserted and exercised similar authority.

C. Authority to Conduct or Carry on Armed Conflict Once It Has
Been Lawfully Instituted

It has never been doubted that the President’s power as Commander in Chief
authorizes him, and him alone, to conduct armed hostilities which have been
lawfully instituted. Chief Justice Chase, concurring in Ex parte Milligan, said:

2
The line between “deploying” forces and “committing them to combat” may be razor thin. Had
Zachary Taylor not encountered Mexican resistance below the Nueces, that example could be classified
as a “deployment,” while if under the orders of President Franklin Roosevelt, discussed infra, Ameri-
can naval vessels had sunk on sight a German submarine in the mid-Atlantic, that example could be
treated as a “commitment to armed conflict.”

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Congress has the power not only to raise and support and govern
armies but to declare war. It has, therefore, the power to provide by
law for carrying on war. This power necessarily extends to all legis-
lation essential to the prosecution of war with vigor and success, ex-
cept such as interferes with the command of the forces and conduct
of campaigns. That power and duty belong to the President as com-
mander-in-chief.
71 U.S. (4 Wall.) 2, 139 (1866) (emphasis supplied).
In the First World War, it was necessary to decide whether United States troops
in France would fight as a separate command under General Pershing, or whether
United States divisions should be incorporated in existing groups or armies
commanded by French or British generals. President Wilson and his military
advisers decided that United States forces would fight as a separate command.
In the Second World War, not only similar military decisions on a global scale
were required, but also decisions that partook as much of political strategy as they
did of military strategy: Should the United States concentrate its military and
materiel resources on either the Atlantic or Pacific fronts to the exclusion of the
other, or should it pursue the war on both fronts simultaneously? Where should the
reconquest of allied territories in Europe and Africa which had been captured by
the Axis powers begin? What should be the goal of the allied powers? Those who
lived through the Second World War will recall without difficulty, and without the
necessity of consulting works of history, that this sort of decision was reached by
the allied commanders in chief, and chief executive officers of the allied nations,
without (on the part of the United States) any formal congressional participation.
The series of conferences attended by President Roosevelt around the world—at
Quebec, Cairo, Casablanca, Teheran, Yalta, and by President Truman at Potsdam,
ultimately established the allied goals in fighting the Second World War, including
the demand for unconditional surrender on the part of the Axis nations.
Similar strategic and tactical decisions were involved in the undeclared Korean
War under President Truman. Questions such as whether United States forces
should not merely defend South Korean territory, but pursue North Korean forces
by invading North Korea, and as to whether American Air Force planes should
pursue North Korean and Chinese Communist planes north of the Yalu River,
separating Red China from North Korea, were of course made by the President as
Commander in Chief without any formal congressional participation.

V. Constitutional Practice Requires Executive to Obtain Sanction of
Congress for Conduct of Major Hostilities

It is too plain from the foregoing discussion to admit of denial that the Execu-
tive, under his power as Commander in Chief, is authorized to commit American
forces in such a way as to seriously risk hostilities, and also to actually commit
them to such hostilities, without prior congressional approval. However, if the

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contours of the divided war power contemplated by the framers of the Constitution
are to remain, constitutional practice must include executive resort to Congress in
order to obtain its sanction for the conduct of hostilities which reach a certain
scale. Constitutional practice also indicates, however, that congressional sanction
need not be in the form of a declaration of war.
In the case of the Mexican War which was brought about, if not initiated, by
the Executive, the President requested and obtained a declaration of war. Con-
gress, meeting in 1861 pursuant to the call of President Lincoln, ratified all of the
actions he had taken on his own initiative, and apparently refrained from declaring
war on the Confederate States only because it did not wish to recognize them as a
sovereign nation.
However, as previously noted, the Fifth Congress authorized President Adams
to take certain military action against France without going so far as to declare
war. More recently, in connection with President Eisenhower’s landing of troops
in Lebanon and with the Cuban missile crisis in 1962, Congress has given advance
authorization for military action by the President without declaring war. Pub. L.
No. 85-7, 71 Stat. 5 (1957); Pub. L. No. 87-733, 76 Stat. 697 (1962).
The notion that such advance authorization by Congress for military operations
constitutes some sort of an invalid delegation of congressional war power simply
will not stand analysis. A declaration of war by Congress is in effect a blank check
to the Executive to conduct military operations to bring about subjugation of the
nation against whom war has been declared. The idea that while Congress may do
this, it may not delegate a lesser amount of authority to conduct military opera-
tions, as was done in the instances referred to above, is both utterly illogical and
unsupported by precedent. While cases such as A.L.A. Schechter Poultry Corp. v.
United States, 295 U.S. 495 (1935), hold that Congress in delegating powers to
deal with domestic affairs must establish standards for administrative guidance, no
such principle obtains in the field of external affairs. The Supreme Court in United
States v. Curtiss-Wright Exp. Corp. made this distinction clear:
Whether, if the Joint Resolution had related solely to internal af-
fairs it would be open to the challenge that it constituted an unlawful
delegation of legislative power to the Executive, we find it unneces-
sary to determine. The whole aim of the resolution is to affect a situ-
ation entirely external to the United States, and falling within the
category of foreign affairs. . . .
It will contribute to the elucidation of the question if we first con-
sider the differences between the powers of the federal government
in respect of foreign or external affairs and those in respect of do-
mestic or internal affairs. That there are differences between them,
and that these differences are fundamental, may not be doubted.
....

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It results that the investment of the federal government with the
powers of external sovereignty did not depend upon the affirmative
grants of the Constitution. The powers to declare and wage war, to
conclude peace, to make treaties, to maintain diplomatic relations
with other sovereignties, if they had never been mentioned in the
Constitution, would have vested in the federal government as neces-
sary concomitants of nationality. . . .
....
In the light of the foregoing observations, it is evident that this
court should not be in haste to apply a general rule which will have
the effect of condemning legislation like that under review as consti-
tuting an unlawful delegation of legislative power. The principles
which justify such legislation find overwhelming support in the un-
broken legislative practice which has prevailed almost from the in-
ception of the national government to the present day.
299 U.S. 304, 315, 318, 322 (1936).
What must be regarded as the high water mark of executive action without
express congressional approval is, of course, the Korean War. Although Congress
never expressly sanctioned the President’s action in committing United States
forces in the hundreds of thousands to the Korean conflict, it repeatedly voted
authorizations and appropriations to arm and equip the American troops. This is
not to say that such appropriations are invariably the equivalent of express
congressional approval; the decision as to whether limited hostilities, commenced
by the Executive, should be sanctioned by Congress may be one quite different
from the decision as to whether American troops already committed and engaged
in such hostilities shall be equipped and supplied.

VI. Extent to Which Congress May Restrict by Legislation the
Substantive Power Granted the President by Virtue of His Being
Designated as Commander in Chief

While the President may commit armed forces of the United States to hostile
conflict without congressional authorization under his constitutional power as
Commander in Chief, his authority exercised in conformity with congressional
authority or ratification of his acts is obviously broader than if it stood alone. By
the same token, Congress undoubtedly has the power in certain situations to
restrict the President’s power as Commander in Chief to a narrower scope than it
would have had in the absence of legislation. Chief Justice Marshall strongly
intimates in his opinion in Little v. Barreme that the executive action directing the
seizure of a ship on the high seas would have been valid had not Congress enacted
legislation restricting the circumstances under which such a seizure was author-

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ized. Congress, exercising its constitutional authority to “make rules concerning
captures on land and water,” may thus constrict the President’s power to direct the
manner of proceeding with such captures.
Congress has similarly sought to restrain the authority of the President in the
exercise of its power to “raise and support Armies.” U.S. Const. art. I, § 8, cl. 12.
In the Selective Service and Training Act of 1940, it was provided that:
Persons inducted into the land forces of the United States under this
Act shall not be employed beyond the limits of the Western Hemi-
sphere except in the Territories and possessions of the United States,
including the Philippine Islands.
Pub. L. No. 76-783, § 3(e), 54 Stat. 885, 886 (1940).
In the year following enactment of this law, President Roosevelt determined to
send United States troops, including draftees, to Iceland in order to relieve British
troops garrisoned there. He chose to strain geography, rather than the law, and
obtained the opinion of what was apparently a minority-view geographer that
Iceland was actually in the Western Hemisphere.
Very recently, Congress has enacted legislation providing that United States
forces shall not be dispatched to Laos or Thailand in connection with the Vietnam
conflict. This proviso was accepted by the Executive.
This is not to say, however, that every conceivable condition or restriction
which Congress may by legislation seek to impose on the use of American
military forces would be free of constitutional doubt. Even in the area of domestic
affairs, where the relationship between Congress and the President is balanced
differently than it is in the field of external affairs, virtually every President since
Woodrow Wilson has had occasion to object to certain conditions in authorization
legislation as being violative of the separation of powers between the Executive
and the Legislative Branch.3 The problem would be met in exacerbated form
should Congress attempt by detailed instructions as to the use of American forces
already in the field to supersede the President as Commander in Chief of the
armed forces. Surely this is the thrust of Chief Justice Chase’s concurring opinion
in Ex parte Milligan, quoted earlier in this text:
[Congressional] power necessarily extends to all legislation essential
to the prosecution of war with vigor and success, except such as in-
terferes with the command of the forces and conduct of campaigns.
That power and duty belong to the President as commander-in-chief.
71 U.S. at 139.

3
All of those Presidents have stated in one way or another that just because Congress concededly
may refrain from appropriating any money at all, it does not necessarily follow that it may attach
whatever condition it desires to an appropriation which it does make.

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Nor is the manner in which armed hostilities may be terminated altogether free
from doubt. All declared wars in our history have been customarily concluded by
treaties negotiated by the President and ratified by the Senate. An effort in the
Constitutional Convention to give Congress the power to declare “peace” as well
as “war” was unanimously turned down at the session of August 17, 1787.
3 Madison Notes at 1353.

VII. The Vietnam Conflict: Relation Between the Power of the
President and the Power of Congress

The duration of the Vietnam conflict, and its requirements in terms of both men
and materiel, have long since become sufficiently large so as to raise the most
serious sort of constitutional question had there been no congressional sanction of
that conflict. However, as is well known, the conflict in its present form began
following an attack on U.S. naval forces in the Gulf of Tonkin in August 1964. At
that time President Johnson took direct air action against the North Vietnamese,
and he also requested Congress “to join in affirming the national determination
that all such attacks will be met” and asked for “a resolution expressing the
support of the Congress for all necessary action to protect our Armed Forces and
to assist nations covered by the SEATO [Southeast Asia Treaty Organization]
Treaty.” H.R. Doc. No. 88-333, at 2 (1964).
On August 10, 1964, Congress passed the following resolution:
Resolved by the Senate and House of Representatives of the Unit-
ed States of America in Congress assembled, That the Congress ap-
proves and supports the determination of the President, as Com-
mander in Chief, to take all necessary measures to repel any armed
attack against the forces of the United States and to prevent further
aggression.
Sec. 2. The United States regards as vital to its national interest
and to world peace the maintenance of international peace and secu-
rity in southeast Asia. Consonant with the Constitution of the United
States and the Charter of the United Nations and in accordance with
its obligations under the Southeast Asia Collective Defense Treaty,
the United States is, therefore, prepared, as the President determines,
to take all necessary steps, including the use of armed force, to assist
any member or protocol state of the Southeast Asia Collective De-
fense Treaty requesting assistance in defense of its freedom.
Sec. 3. The resolution shall expire when the President shall de-
termine that the peace and security of the area is reasonably assured
by international conditions created by action of the United Nations

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or otherwise, except that it may be terminated earlier by concurrent
resolution of the Congress.
Pub. L. No. 88-408, 78 Stat. 384, 384 (1964).
In connection with this resolution, Congress noted that whatever the limits of
the President’s authority acting alone might be, whenever Congress and the
President act together “‘there can be no doubt’” of the constitutional authority.
H.R. Rep. 88-1708, at 4 (1964) (committee report on Gulf of Tonkin resolution,
quoting committee report on Formosa resolution).
Since that time, Congress has repeatedly adopted legislation recognizing the
situation in Southeast Asia, providing the funds to carry out United States
commitments there, and providing special benefits for troops stationed there. By
virtue of these acts, and by virtue of the provision in the Gulf of Tonkin resolution
as to the manner in which it may be terminated, there is long-standing congres-
sional recognition of a continuing United States commitment in Southeast Asia.4
President Nixon has continued to maintain United States troops in the field in
South Vietnam, in pursuance of his policy to seek a negotiated peace which will
protect the right of the South Vietnamese people to self-determination. The
legality of the maintenance of these troops in South Vietnam, and their use to
render assistance to the South Vietnamese troops in repelling aggression from the
Viet Cong and the North Vietnamese, would admit of reasonable doubt only if
congressional sanction of hostilities commenced on the initiative of the Executive
could be manifested solely by a formal declaration of war. But the numerous
historical precedents previously cited militate against such a formal type of
reasoning.
A requirement that congressional approval of executive action in this field can
come only through a declaration of war is not only contrary to historic constitu-
tional usage, but as a practical matter could not help but curtail effective congres-
sional participation in the exercise of the shared war power. If Congress may
sanction armed engagement of United States forces only by declaring war, the
possibility of its retaining a larger degree of control through a more limited
approval is foreclosed. While in terms of men and materiel the Vietnam conflict is
one of large scale, the objectives for which the conflict may be carried on, as set
forth in the Gulf of Tonkin resolution, are by no means as extensive or all-
inclusive as would have resulted from a declaration of war by Congress. Con-

4
“Legislative history” surrounding the Gulf of Tonkin resolution may be cited for a number of
varying interpretations of exactly what Congress was authorizing. In view of the very plain text of the
resolution, which authorizes the use of military force “as the President determines” to assist Southeast
Asian countries, including South Vietnam, in defense of their freedom, Pub. L. No. 88-408, § 2, 78
Stat. at 384, it is all but impossible to argue that substantial military operations in support of the South
Vietnamese against North Vietnam and the Viet Cong were not thereby authorized. The fact that
Congress did not by adopting this resolution intend to declare war does not detract from this
conclusion; the authority conferred by the resolution is a good deal short of that which would be
conferred by a declaration of war.

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versely, however, there cannot be the slightest doubt from an examination of the
language of the Gulf of Tonkin resolution that Congress expressly authorized
extensive military involvement by the United States, on no less a scale than that
now existing, by virtue of its adoption of this resolution. To reason that if the
caption “Declaration of War” had appeared at the top of the resolution, this
involvement would be permissible, but that the identical language without such a
caption does not give effective congressional sanction to it at all, would be to treat
this most nebulous and ill defined of all areas of the law as if it were a problem in
common law pleading. Justice Grier, more than a century ago, in the Prize Cases
said:
This greatest of civil wars was not gradually developed by popu-
lar commotion, tumultuous assemblies, or local unorganized insur-
rections. However long may have been its previous conception, it
nevertheless sprung forth suddenly from the parent brain, a Minerva
in the full panoply of war. The President was bound to meet it in the
shape it presented itself, without waiting for Congress to baptize it
with a name; and no name given to it by him or them could change
the fact.
67 U.S. at 668–69. If substance prevailed over form in establishing the right of the
federal government to fight the Civil War in 1861, substance should equally
prevail over form in recognizing congressional sanction for the Vietnam conflict
by the Gulf of Tonkin resolution, even though it was not in name or by its terms a
formal declaration of war.
Viewed in this context, the President’s determination to authorize incursion
into the Cambodian border area by United States forces in order to destroy
sanctuaries utilized by the enemy is the sort of tactical decision traditionally
confided to the Commander in Chief in the conduct of armed conflict. From the
time of the drafting of the Constitution it has been clear that the Commander in
Chief has authority to take prompt action to protect American lives in situations
involving hostilities. Faced with a substantial troop commitment to such hostilities
made by the previous Chief Executive, and approved by successive Congresses,
President Nixon has an obligation as Commander in Chief of the country’s armed
forces to take what steps he deems necessary to assure their safety in the field. A
decision to cross the Cambodian border, with at least the tacit consent of the
Cambodian government, in order to destroy sanctuaries being utilized by North
Vietnamese in violation of Cambodia’s neutrality, is wholly consistent with that
obligation. It is a decision made during the course of an armed conflict as to how
that conflict shall be conducted, rather than a determination that some new and
previously unauthorized military venture shall be undertaken.
By crossing the Cambodian border to attack sanctuaries used by the enemy, the
United States has in no sense gone to “war” with Cambodia. United States forces
are fighting with or in support of Cambodian troops, and not against them.

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Whatever protest may have been uttered by the Cambodian government was
obviously the most perfunctory, formal sort of declaration. The Cambodian
incursion has not resulted in a previously uncommitted nation joining the ranks of
our enemies, but instead has enabled us to more effectively deter enemy aggres-
sion heretofore conducted from the Cambodian sanctuaries.
Only if the constitutional designation of the President as Commander in Chief
conferred no substantive authority whatever could it be said that prior congres-
sional authorization for such a tactical decision was required. Since even those
authorities least inclined to a broad construction of the executive power concede
that the Commander in Chief provision does confer substantive authority over the
manner in which hostilities are conducted, the President’s decision to invade and
destroy the border sanctuaries in Cambodia was authorized under even a narrow
reading of his power as Commander in Chief.

WILLIAM H. REHNQUIST
Assistant Attorney General
Office of Legal Counsel

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