Opinion for the Court filed by Circuit Judge ROBB.
Dissenting opinion filed by Circuit Judge MacKINNON.
ROBB, Circuit Judge:In this case Philip Agee challenges a regulation relied on by the United States Department of State to revoke his passport. The District Court, 483 F.Supp. 729, declared the regulation invalid for lack of congressional authorization and restored the passport. We affirm.
Appellee Philip Agee, a United States citizen and a former employee of the Central Intelligence Agency (CIA), presently resides in Hamburg, West Germany. Agee is a leading critic of the CIA’s clandestine operations throughout the world. He has written and spoken extensively attacking American intelligence efforts, and has purportedly revealed the identities of certain undercover CIA agents. Agee was issued a United States passport, No. Z3007741, on March 30, 1978, with an expiration date of March 29, 1983. However, the United States Department of State, aware of Agee’s activities and perhaps believing that they took on special significance because of the Iranian crisis1 and the recent unrest in other Islamic countries, moved to revoke his passport.
On December 23, 1979 the United States Consul General in Hamburg delivered to Agee a letter from the Department of State notifying him that his passport was immediately revoked and should be surrendered. The letter invoked the authority of 22 C.F.R. §§ 51.70(b)(4) & 51.71(a) (1979). 22 C.F.R. § 51.70(b)(4) (1979) provides:
A passport may be refused in any case in which:
*82The Secretary determines that the national’s activities abroad are causing or are likely to cause serious damage to the national security or the foreign policy of the United States .
22 C.F.R. § 51.71(a) (1979) states:
A passport may be revoked, restricted or limited where:
The national would not be entitled to issuance of a new passport under § 51.70
According to the State Department letter
The Department’s action is predicated upon a determination made by the Secretary under the provisions of Section 51.-70(b)(4) that your activities abroad are causing or are likely to cause serious damage to the national security or the foreign policy of the United States. The reasons for the Secretary’s determination are, in summary, as follows: Since the early 1970’s it has been your stated intention to conduct a continuous campaign to disrupt the intelligence operations of the United States. In carrying out that campaign you have travelled in various countries (including, among others, Mexico, the United Kingdom, Denmark, Jamaica, Cuba, and Germany), and your activities in those countries have caused serious damage to the national security and foreign policy of the United States. Your stated intention to continue such activities threatens additional damage of the same kind.
(J.A. at 13). The letter also informed Agee of his right to administrative review, and the Department of State subsequently offered him a hearing on an expedited basis. Agee rejected this option, however, and on December 31, 1979, he sued Cyrus Yance, who was then Secretary of State, in the District Court. The complaint sought declaratory and injunctive relief.
Agee’s complaint challenged the revocation of his passport on five grounds: (1) that 22 C.F.R. § 51.70(b)(4) has not been authorized by Congress and is therefore invalid; (2) that 22 C.F.R. § 51.70(b)(4) is impermissibly vague and overbroad; (3) that the revocation of his passport prior to a hearing violated his Fifth Amendment right to procedural due process; (4) that the revocation of his passport violated his right to travel — a liberty interest protected by the Fifth Amendment; and (5) that his passport was revoked in order to punish, him and suppress his criticism of government policy in violation of the First Amendment. In proceedings before the District Court on January 3, 1980, Agee’s counsel, for the purposes of attacking the Secretary’s authority to adopt and apply 22 C.F.R. § 51.-70(b)(4), conceded the truth of “the charges as they are made in the letter to Agee.” (Tr. at 16). On January 18, 1980 the case was orally argued to the District Court on cross-motions for summary judgment.
By Memorandum and Order dated January 28, 1980 the District Court granted summary judgment to Agee and ordered the restoration of his passport. The District Court concluded that “[t]he Secretary of State’s power to revoke or limit a passport flows from Congress not from the President” and “[h]is power is no greater than Congress may choose to delegate to him.” Accordingly the court held that 22 C.F.R. § 51.70(b)(4) is invalid because “the Secretary’s promulgation of the challenged regulation was without [express or implied] authorization from Congress.” On January 29, 1980 the Secretary of State filed a notice of appeal from the District Court’s decision, and by Orders dated February 4 and 5, 1980 this court granted the Secretary’s motion for a stay pending appeal.
As authority to promulgate and enforce 22 C.F.R. § 51.70(b)(4), the Secretary of State relies on the Passport Act of 1926, 22 U.S.C. § 211a (1976), which at the time the regulation was adopted in 1968 provided that:
The Secretary of State may grant and issue passports, and cause passports to be granted, issued, and verified in foreign countries by diplomatic representatives of the United States, and by such consul generals, consuls, or vice consuls when in charge, as the Secretary of State may designate and by the chief or other executive officer of the insular possessions of *83the United States, under such rules as the President shall designate and prescribe for and on behalf of the United States, and no other persons shall grant, issue, or verify such passports.2
In Kent v. Dulles, 357 U.S. 116, 78 S.Ct. 1113, 2 L.Ed.2d 1204 (1958), the Secretary of State had denied two passport applications pursuant to a regulation promulgated in reliance on 22 U.S.C. § 211a. The regulation prohibited the issuance of passports to members of the Communist Party or to persons who “engage in activities which support the Communist movement” or “are going abroad to engage in activities which will advance the Communist movement for the purpose, knowingly and wilfully of advancing that movement.” Id. at 117-18 n.1, 78 S.Ct. at 1114 n.l. The Supreme Court held that “[t]he right to travel is a part of the ‘liberty’ of which the citizen cannot be deprived without due process of law under the Fifth Amendment,” and, therefore, “[i]f that ‘liberty’ is to be regulated, it must be pursuant to the law-making functions of the Congress.” Id. at 125, 129, 78 S.Ct. at 1118, 1120. Further, the Court stated that it would “construe narrowly all delegated powers that curtail or dilute [the right to travel].” Id. at 129, 78 S.Ct. at 1120. The Court held that Congress did not give the Secretary of State “unbridled discretion to grant or withhold a passport from a citizen for any substantive reason he may choose”, and that the only grounds for refusing a passport “which it could fairly be argued were adopted by Congress in light of prior administrative practice” were “relate[d] to citizenship or allegiance on the one hand or to criminal or unlawful conduct on the other.” Id. at 127-128, 78 S.Ct. at 1119. The Court explained that:
The difficulty is that while the power of the Secretary of State over the issuance of passports is expressed in broad terms, it was apparently long exercised quite narrowly. So far as material here, the cases of refusal of passports generally fell into two categories. First, questions pertinent to the citizenship of the applicant and his allegiance to the United States had to be resolved by the Secretary, for the command of Congress was that “No passport shall be granted or issued to or verified for any other persons than those owing allegiance, whether citizens or not, to the United States.” 32 Stat. 386, 22 U.S.C. § 212. Second, was the question whether the applicant was participating in illegal conduct, trying to escape the toils of the law, promoting passport frauds, or otherwise engaging in conduct which would violate the laws of the United States.
Id. at 127, 78 S.Ct. at 1119. Thus, the Court, observing that the State Department rulings concerning Communists were “scattered” and “not consistently of one pattern”, concluded that the regulation employed to deny passports to members and supporters of the Communist Party lacked congressional authorization and was therefore invalid. Id. at 128-30, 78 S.Ct. at 1119-1120.
In Zemel v. Rusk, 381 U.S. 1, 85 S.Ct. 1271, 14 L.Ed.2d 179 (1965), the Supreme Court considered the validity of an area travel ban imposed by the Secretary of State to prohibit travel to Cuba by all United States citizens. The Court reasoned that the language of 22 U.S.C. § 211a “is surely broad enough to authorize area restrictions, and there is no legislative history indicating an intent to exclude such restrictions from *84the grant of authority.” Id. at 8, 85 S.Ct. at 1276. Noting that area restrictions were imposed on numerous occasions both before and after the Passport Act was adopted in 1926, the Court held that the ban on travel to Cuba was valid because there was “an administrative practice sufficiently substantial and consistent to warrant the conclusion that Congress had implicitly approved it.” Id. at 8-12, 85 S.Ct. at 1279. In addition, the Court stated that, unlike the denial of the passport applications in Kent v. Dulles, supra, “the Secretary has refused to validate appellant’s passport not because of any characteristic peculiar to appellant [i. e., political beliefs or associations], but rather because of foreign policy considerations affecting all citizens.” Id. at 13,3 85 S.Ct. at 1279.
This court has also considered the issue of congressional authorization for administrative actions impacting on the right of international travel. In Woodward v. Rogers, 344 F.Supp. 974 (D.D.C.1972), aff’d without opinion, 159 U.S.App.D.C. 57, 486 F.2d 1317 (1973), this court summarily affirmed the District Court’s holding that there existed neither explicit nor implicit statutory authority for requiring an oath of allegiance as a prerequisite to the issuance of a passport. The District Court said:
While an Oath of Allegiance may, indeed, have been included on the passport *85application for an extended period, travel abroad until recently was not conditioned upon the possession of a passport, with the exception of limited periods of international hostilities or national emergency. Moreover, there has been no evidence introduced establishing an open and highly published practice of denying applicants passports for simply refusing to swear to or affirm the Oath. Under these circumstances, this Court is extremely reluctant to conclude that Congress, in re-enacting the passport legislation in 1952, indicated a clear intention to authorize the Secretary of State to establish the Oath requirement as a prerequisite to the exercise of a citizen’s constitutionally protected right to travel. Indeed, the Supreme Court has made it plain that only the clearest of such evidence will permit this Court to consider Congressional silence to be a substitute for explicit and affirmative legislative action in limiting the free exercise of important rights.
344 F.Supp. at 985. In Lynd v. Rusk, 128 U.S.App.D.C. 399, 389 F.2d 940 (1967), this court held that the Secretary of State could not withhold a citizen’s passport for failure to give assurance that he would not travel without a passport to those countries where the Secretary had designated travel to be inimical to the nation’s foreign policy. The court reasoned that “[although Congress has approved administrative action intended to limit travel to restricted areas through the means of restricting passports, . it has not made travel to restricted areas a crime and added possible deprivation of liberty as a sanction for achieving this objective”; and thus the court concluded that there was no “basis for inferring that Congress has given the Secretary the authority to deny legitimate, constitutionally protected travel, merely because that is a technique which provides greater assurance of hindering travel to designated areas.” 128 U.S.App.D.C. at 405, 389 F.2d at 946-947.
In summary, as the case law makes clear, the Secretary of State must demonstrate that Congress has authorized 22 C.F.R. § 51.70(b)(4) either by an express delegation or by a “sufficiently substantial and consistent” administrative practice to warrant finding the implied approval of Congress.
The Secretary argues that the Passport Act of 1926, 22 U.S.C. § 211a, interpreted consistently with the President’s power to protect national security and conduct foreign affairs, authorizes the revocation of Agee’s passport under 22 C.F.R. § 51.-70(b)(4), especially in light of Agee’s concession for purposes of his summary judgment motion that his activities seriously damage the national security and the foreign policy of the United States. However, the Passport Act does not expressly authorize the Secretary to deny or revoke a passport on national security or foreign policy grounds, and no subsequent legislation relating to passports has explicitly delegated such authority. In fact, in .1958 and in 1966 the Department of State unsuccessfully sought this precise power from Congress,4 and in 1978 Congress limited the Secretary’s discretion, as upheld in Zemel v. Rusk, supra, to impose area restrictions on travel.5 To be sure the failure to enact the legislation sought by the Department of State and the contraction of executive power over area restrictions do not conclusively signify congressional disapproval of 22 C.F.R. § 51.-70(b)(4); but neither do they support the Secretary’s construction of 22 U.S.C. § 211a as a broad delegation of authority to regulate. Moreover, with regard to the inherent foreign affairs power of the executive, the *86Supreme Court emphasized in Baker v. Carr, 369 U.S. 186, 211, 82 S.Ct. 691, 707, 7 L.Ed.2d 663 (1962), that “it is error to suppose that every case or controversy which touches foreign relations lies beyoiid judicial cognizance”, and we reaffirm what this court stated in Lynd v. Rusk, supra:
[I]n the cases before us the Secretary does not press any claim that he has an “inherent” authority, and contends his action is valid under the Passport Act of 1926. It is not insignificant that the Zemel opinion, supporting the Secretary, did not rely on an inherent authority. We think any claim of inherent authority would fall afoul of the Supreme Court’s warning in Kent v. Dulles, 357 U.S. 116, at 129 [78 S.Ct. at 1119] [2 L.Ed.2d 1204] (1958), that as freedom to travel is part of the “liberty” protected by the Fifth Amendment, “if that ‘liberty’ is to be regulated, it must be pursuant to the law-making functions of the Congress.”
128 U.S.App.D.C. at 403, 389 F.2d at 944.
The Secretary contends that past administrative and legislative practice also confirms congressional approval of his authority to deny or revoke passports on the basis of “serious damage to the national security or the foreign policy of the United States.” However, the Secretary details only one instance in twelve years in which 22 C.F.R. § 51.70(b)(4) was employed to revoke a passport,6 and only five refusals of passport applications, two prior to the passage of the Passport Act of 1926 and three during the mid-1950’s, which were even arguably for national security or foreign policy reasons.7 Regardless of whether Congress was aware of these scattered examples when it adopted the Passport Act in 1926 and other travel control legislation in 1941, 1952, and 1978, such evidence hardly amounts to a “substantial and consistent administrative practice” demonstrating implied congressional authorization for the challenged regulation. Until Agee’s case arose. 22 C.F.R. § 51.-70(b)(4)) was virtually unused.
In addition, the Secretary relies on a series of statutes, regulations, proclamations, orders and advisory opinions dating back to 1856, most of which concern the power of the executive to refuse passports to persons engaged in criminal conduct and to restrict or condition the issuance of passports during time of war or national emergency;8 *87but such measures are inapposite and unpersuasive on the issue of implicit authority to invoke national security or foreign policy considerations during peacetime. See Kent v. Dulles, supra, 357 U.S. at 128, 78 S.Ct. at 1119. Further, as illustrated by the Supreme Court’s decisions in Kent v. Dulles, supra at 127, 78 S.Ct. at 1118, and Zemel v. Rusk, supra 381 U.S. at 8, 85 S.Ct. at 1276, the criterion for establishing congressional assent by inaction is the actual imposition of sanctions and not the mere assertion of power. “[0]nly the clearest . . . evidence [of past administrative and legislative practice] will permit this Court to consider Congressional silence to be a substitute for explicit and affirmative legislative action in limiting the free exercise of important rights.” Woodward v. Rogers, 344 F.Supp. at 985. Such proof is lacking here.
We conclude that 22 C.F.R. § 51.-70(b)(4) was promulgated by the Secretary of State and enforced against Agee without the requisite express or implied authorization of Congress.9 The Secretary may not revoke Agee’s passport unless Congress has authorized him to do so, for “the right to travel abroad” is constitutionally protected and subject to regulation only “pursuant to the law-making functions of the Congress.” See Aptheker v. Secretary of State, 378 U.S. 500,505, 84 S.Ct. 1659, 1663, 12 L.Ed.2d 992 (1964); Kent v. Dulles, supra 357 U.S. at 129, 78 S.Ct. at 1119.
The decisions of the Supreme Court would permit the revocation of Agee’s passport if he were indicted or otherwise charged with criminal conduct,10 but he has not been charged with any violation of law. The State Department’s letter revoking his passport makes no such charge. Under the decisions it is not enough, absent a formal allegation of criminal activity, that Agee’s conduct may be considered by some to border on treason. We are bound by the law as we find it.
The judgment of the District Court declaring 22 C.F.R. § 51.70(b)(4) invalid and ordering the restoration of Agee’s passport is affirmed, and the stay pending appeal is vacated.
So ordered.
. An article in the New York Post on December 17, 1979 reported that Agee would be invited to visit Iran and serve on an “international tribunal” created by Ayatollah Khomeini to pass judgment on the prisoners held in the American Embassy in Tehran. Agee denied being “invited to Iran by its government, The Revolutionary Council, or any representative thereof . ” (J.A. 98), but resolution of this factual dispute is irrelevant to our decision. See note 3 infra.
. Section 211a was amended in 1978 by the addition of the following language:
Unless authorized by law, a passport may not be designated as restricted for travel to or for use in any country other than a country with which the United States is at war, where armed hostilities are in progress, or where there is imminent danger to the public health or the physical safety of United States travellers.
22 U.S.C. § 211a (Supp. II 1978).
By Executive Order No. 11295 (August 5, 1966), 31 Fed.Reg. 10603, the Secretary of State was “designated and empowered to exercise, without the approval, ratification, or other action of the President, the authority conferred upon the President by the first section of the Act of July 3, 1926 (22 U.S.C. 211a), to designate and prescribe for and on behalf of the United States rules governing the granting, issuing, and verifying of passports.”
. The dissent emphasizes this reference in Zemel v. Rusk to “foreign policy considerations”, as well as the Supreme Court’s statement that “the restriction which is challenged in this case is supported by the weightiest considerations of national security [as] is perhaps best pointed up by recalling that the Cuban missile crisis of October 1962 preceded the filing of appellant’s complaint by less than two months." 381 U.S. at 13, 16, 85 S.Ct. at 1280. The dissent suggests that Zemel v. Rusk upholds passport revocations on foreign policy and national security grounds in the broad sense of those terms. In our view, however, Zemel v. Rusk holds only that, in light of the extensive history of executive imposition of area restrictions on travel, such restrictions are valid because they have received congressional authorization. See id. at 8-12, 85 S.Ct. at 1276-1278. The heart of the Zemel opinion is the Supreme Court’s statement that “[t]his case is therefore not like Kent v. Dulles, supra, where we were unable to find ... an administrative practice sufficiently substantial and consistent to warrant the conclusion that Congress had implicitly approved it.” 381 U.S. at 12, 85 S.Ct. at 1279. Although the Secretary’s 1961 ban on travel to Cuba assuredly involved foreign policy and national security considerations, so too did the Secretary’s denial of passports to Communist party members and sympathizers pursuant to 22 C.F.R. § 51.135, which was struck down in Kent v. Dulles. Rather than broadly validating passport revocations on foreign policy and national security grounds, Zemel v. Rusk merely sustained one means of satisfying those concerns — the imposition of area restrictions — because it had been “implicitly approved” by Congress.
The dissent also notes the Supreme Court’s citation in the Zemel opinion of 22 U.S.C. § 1732, which directs the President to “use such means, not amounting to acts of war, as he may think necessary and proper to obtain or effectuate the release” of “any citizen of the United States [who] has been unjustly deprived of his liberty by or under the authority of any foreign government.” The Zemel Court stated:
It also cannot be forgotten that in the early days of the Castro regime, United States citizens were arrested and imprisoned without charges. We think, particularly in view of the President’s statutory obligation [under 22 U.S.C. § 1732], that the Secretary has justifiably concluded that travel to Cuba by American citizens might involve the Nation in dangerous international incidents, and that the Constitution does not require him to validate passports for such travel.
381 U.S. at 15, 85 S.Ct. at 1280. The dissent argues that 22 U.S.C. § 1732 authorized the revocation of Agee’s passport as part of the President’s efforts to free the. Americans held hostage in Iran. However, in revoking Agee’s passport, the Secretary did not rely on 22 U.S.C. § 1732 and, in fact, made no mention whatsoever of the Iranian crisis. According to the letter that Agee received from the Department of State, the Secretary relied only on 22 C.F.R. §§ 51.70(b)(4) & 51.71(a) as authority for his action, and the sole reasons offered for his decision were that:
Since the early 1970’s it has been your stated intention to conduct a continuous campaign to disrupt the intelligence operations of the United States. In carrying out that campaign you have travelled in various countries (including, among others, Mexico, the United Kingdom, Denmark, Jamaica, Cuba, and Germany), and your activities in those countries have caused serious damage to the national security and foreign policy of the United States. Your stated intention to continue such activities threatens additional damage of the same kind.
(J.A. at 13). Thus, 22 U.S.C. § 1732 is not germane to this case.
. S. 4110, 85th Cong., 2d Sess. (1958), introduced by Senator Green at the request of the Secretary of State, would have permitted the denial of passports to persons whose activities or presence abroad would “seriously impair the conduct of the foreign relations of the United States” or would “be inimical to the security of the United States.” H.R. 14895, 89th Cong., 2d Sess. (1966), introduced by Representative Hays, would have sanctioned the refusal or revocation of a passport if “the Secretary determines that the applicant’s activities abroad are causing or are likely to cause serious damage to the national security or the foreign policy of the United States.” Both these bills died in committee and were never brought to a vote.
. See note 2 supra.
. In 1970 the passports of Charles McKissack, attorney for Mrs. Mary Sirhan, and his assistant were revoked pursuant to 22 C.F.R. § 51.-70(b)(4) as they were preparing to leave the United States, and they were unsuccessful in their attempts to enjoin the revocations. (Br. for Appellant at 46).
. In 1906 a passport was denied to an Ameri-' can citizen who had traveled to China and became notorious as a promoter of gambling and prostitution. In 1907 a passport was denied to Nelken Waldberg, an American citizen living in Cairo, who “was engaged ... in blackmailing projects, and was disturbing, or endeavoring to disturb, the relations of this country with the representatives of foreign countries.” Id. at 37-38.
Colonel Hubert Julian, whose activities included supplying arms to various countries, was denied a passport in 1954. In 1955 two passport applications were refused because the applicants’ participation in political affairs abroad had become an internal problem to the foreign governments involved. Id. at 46; (Rep.Br. for Appellant at 17 & n.15). In addition, the Secretary notes that the statistics provided to the Senate Foreign Relations Committee during hearings in 1957 showed that, apart from numerous “passport refusals for security reasons” that were related to 22 C.F.R. § 51.-135, the Communist regulation held invalid in Kent v. Dulles, twenty-one passport applications in 1955 and ten passport applications in 1956 were refused because the applicants were “participants in political affairs abroad whose activities were deemed harmful to good relations and persons whose previous conduct abroad has been such as to bring discredit on the United States and cause difficulty for other Americans (gave bad checks, left unpaid debts, had difficulty with police, etc.).” (Br. for Appellant at 44); Department of State Passport Policies, Hearings before the Senate Committee on Foreign Relations, 85th Cong., 1st Sess. 38-40 (1957).
The rationale for these passport denials, however, appears only tenuously related to 22 C.F.R. § 51.70(b)(4)’s concern with “serious damage to the national security or the foreign policy of the United States.”
. See, e. g., Pub.L.No.65-154, 40 Stat. 559 (1918); Pub.L.No.77-114, 55 Stat. 252 (1941); Pub.L.No.82 — 414, 66 Stat. 190 (1952); Pub.L. No.95-426, 92 Stat. 971 (1978); 23 Op.Atty. Gen. 509, 511 (1901); Proclamation No. 1473, 40 Stat. 1829 (1918); 17 Fed.Reg. 8013 (1952).
. Because we so hold, we need not consider Agee’s constitutional attacks on the regulation and its application to him based on the First and Fifth Amendments.
. See Kent v. Dulles, supra, 357 U.S. at 127-28, 78 S.Ct. at 1118-1119. 22 C.F.R. § 51.-70(a)(1) (1979) provides for the denial or revocation of a passport if “[t]he applicant is the subject of an outstanding Federal warrant of arrest for a felony, including a warrant issued under the Federal Fugitive Felon Act (18 U.S.C. 1073) . . . .”
In Snepp v. United States, 444 U.S. 507, 517 & n.3, 100 S.Ct. 763, 769, & n.3, 62 L. Ed.2d 704 (1980), Mr. Justice Stevens observed in his dissent that “Congress has enacted a number of criminal statutes punishing the unauthorized dissemination of certain types of classified information” including “18 U.S.C. § 798, which imposes a prison term of 10 years and a $10,000 fine for knowingly and wilfully publishing certain types of classified information” and “18 U.S.C. § 794, which makes it a criminal offense punishable by life in prison to communicate national defense information to a foreign government.” The Secretary, in fact, acknowledges that Agee may be in violation of 18 U.S.C. § 793 because he “has ‘communicated’ ‘to persons not entitled to receive it’ ‘information relating to the national defense’ which could be ‘used to the injury of the United States.’ ” (Br. for Appellant at 23 n.8).'