Mr. Chief Justice Warren
delivered the opinion of the Court.
The questions for decision are whether the Secretary of State is statutorily authorized to refuse to validate the passports of United States citizens for travel to Cuba, and, if he is, whether the exercise of that authority is constitutionally permissible. We answer both questions in the affirmative.
Prior to 1961 no passport was required for travel anywhere in the Western Hemisphere. On January 3 of that year, the United States broke diplomatic and consular relations with Cuba. On January 16 the Department of State eliminated Cuba from the area for which passports were not required, and declared all outstanding United States passports (except those held by persons already in Cuba) to be invalid for travel to or in Cuba “unless specifically endorsed for such travel under the authority of the Secretary of State.” A companion press release stated that the Department contemplated granting exceptions to “persons whose travel may be regarded as being in the best interests of the United States, such as newsmen or businessmen with previously established business interests.”
Through an exchange of letters in early 1962, appellant, a citizen of the United States and holder of an otherwise valid passport, applied to the State Department to have his passport validated for travel to Cuba as a tourist. His [4]*4request was denied. On October 30, 1962, he renewed the request, stating that the purpose of the proposed trip was “to satisfy my curiosity about the state of affairs in Cuba and to make me a better informed citizen.” The request again was denied, on the ground that the purpose of the trip did not meet the previously prescribed standards for such travel.
On December 7, 1962, appellant instituted this suit against the Secretary of State and the Attorney General in the United States District Court for the District of Connecticut, seeking a judgment declaring: (1) that he was entitled under the Constitution and laws of the United States to travel to Cuba and to have his passport validated for that purpose; (2) that his travel to Cuba and the use of his passport for that purpose would not violate any statute, regulation, or passport restriction; (3) that the Secretary’s restrictions upon travel to Cuba were invalid; (4) that the Passport Act of 1926 and § 215 of the Immigration and Nationality Act of 1952 were unconstitutional; (5) that the Secretary’s refusal to grant him a passport valid for Cuba violated rights guaranteed him by the Constitution and the United Nations Declaration of Human Rights; and (6) that denial of the passport endorsement without a formal hearing violated his rights under the Fifth Amendment.1 The complaint also requested that the Secretary be directed to validate appellant’s passport for travel to Cuba and that the Secretary and the Attorney General be enjoined from interfering with such travel. In his amended complaint, appellant added to his constitutional attack on the 1926 and 1952 Acts a prayer that the Secretary and the Attorney General be enjoined from enforcing them.
On appellant’s motion, and over the objection of appellees, a three-judge court was convened. On cross-[5]*5motions for summary judgment, the court, by a divided vote, granted the Secretary of State’s motion for summary judgment and dismissed the action against the Attorney General, 228 F. Supp. 65 (D. C. D. Conn. 1964). We postponed consideration of the jurisdictional question to the hearing of the case on the merits, 379 U. S. 809.
I.
A direct appeal to this Court from a district court lies under 28 U. S. C. § 1253 (1958 ed.) only “from an order granting or denying ... an interlocutory or permanent injunction in any civil action, suit or proceeding required by any Act of Congress to be heard and determined by a district court of three judges.” Thus we must deal first with the Government’s contention that a three-judge court was improperly convened, for if the contention is correct, this Court lacks jurisdiction over the appeal. Phillips v. United States, 312 U. S. 246, 248.
Section 2282 of Title 28 of the United States Code requires the impanelling of a three-judge court in any case where the relief sought is “[a]n interlocutory or permanent injunction restraining the enforcement, operation or execution of any Act of Congress for repugnance to the Constitution of the United States . . . .” On its face, appellant’s amended complaint, by calling upon the court below to enjoin the enforcement of the Passport Act of 1926 and § 215 of the Immigration and Nationality Act of 1952,-on the ground that those statutes are unconstitutional, meets the requirements of § 2282. The Solicitor General notes that appellant would be accorded full relief by the voiding of the Secretary’s order. It is true that appellant’s argument — that either the Secretary’s order is not supported by the authority granted him by Congress, or the statutes granting that authority are unconstitutional — is two-pronged. But we have often held that a [6]*6litigant need not abandon his nonconstitutional arguments in order to obtain a three-judge court: “the joining in the complaint of a nonconstitutional attack along with the constitutional one does not dispense with the necessity to convene such a court.” 2
The Solicitor General, apparently conceding — as all three judges below agreed — that appellant’s Fifth Amendment attack is substantial, cf. Kent v. Dulles, 357 U. S. 116, 125; Aptheker v. Secretary of State, 378 U. S. 500, 505-506, argues that it is in reality an attack upon an administrative, as opposed to a legislative, policy, and therefore, under cases like Phillips v. United States, 312 U. S. 246, and Ex parte Bransford, 310 U. S. 354, a three-judge court need not have been convened. We need not evaluate this contention, for appellant’s complaint also attacks the 1926 and 1952 Acts on the ground that “they contain no standards and are therefore an invalid delegation of legislative power.” This allegation cannot be brushed aside as an attack upon the actions of the Secretary; in arguing invalid delegation, appellant has quite clearly assailed the statutes themselves. The Solicitor General therefore meets the delegation argument on another ground: by labeling it “frivolous.” Although we do not accept appellant’s delegation argument, infra, pp. 17-18, we cannot agree that it is so insubstantial as to compel a district court to read it out of the complaint and refuse to convene a three-judge court. Compare William Jameson & Co. v. Morgenthau, 307 U. S. 171; Schneider v. Rusk, 372 U. S. 224. Indeed, we explicitly noted in Kent v. Dulles, supra, at 129, that if we had held that the Secretary’s refusal to issue a passport to petitioner in that case was supported by the 1926 and 1952 Acts, we would [7]*7then have been obliged to consider whether those Acts were void for invalid delegation.3
The complaint therefore launches a substantial constitutional attack upon two federal statutes, and prays that their operation be enjoined. Cf. Idlewild Liquor Corp. v. Epstein, 370 U. S. 713, 715. We hold that the three-judge court was properly convened, and that we therefore have jurisdiction over the appeal.4
H-1 I — i
We think that the Passport Act of 1926, 44 Stat. 887, 22 U. S. C. § 211a (1958 ed.), embodies a grant of authority to the Executive to refuse to validate the passports of United States citizens for travel to Cuba. That Act provides, in pertinent part:
“The Secretary of State may grant and issue passports . . . under such rules as the President shall [8]*8designate and prescribe for and on behalf of the United States . ...” 5
This provision is derived from § 23 of the Act of August 18, 1856, 11 Stat. 52, 60-61, which had, prior to 1926, been re-enacted several times without substantial change. The legislative history of the 1926 Act and its predecessors does not, it is true, affirmatively indicate an intention to authorize area restrictions. However, its language is surely broad enough to authorize area restrictions, and there is no legislative history indicating an intent to exclude such restrictions from the grant of authority; these factors take on added significance when viewed in light of the fact that during the decade preceding the passage of the Act, the Executive had imposed both peacetime and wartime area restrictions. As a result of a famine in Belgium in 1915, the State Department stopped issuing passports for use in that country except to “applicants obliged to go thither by special exigency or authorized by Red Cross or Belgian Relief Commission.” Ill Hack-worth, Digest of International Law, p. 526 (1942). Beginning December 9, 1914, and continuing through World War I, passports were validated only for specific purposes and specific countries. No passports were issued for travel in Germany and Austria until July 18, 1922, and none for the Soviet Union until approximately September 1923. [9]*9Hearings before the Senate Committee on Foreign Relations on Department of State Passport Policies, 85th Cong., 1st Sess., pp. 63-64. The use in the 1926 Act of language broad enough to permit executive imposition of area restrictions, after the Executive had several times in the recent past openly asserted the power to impose such restrictions under predecessor statutes containing substantially the same language, supports the conclusion that Congress intended in 1926 to maintain in the Executive the authority to make such restrictions.6
This construction of the Act is reinforced by the State Department’s continued imposition of area restrictions during both times of war and periods of peace since 1926. For a period of about seven months following the outbreak of war between Italy and Ethiopia in 1935, the Department declined to issue passports for travel in Ethiopia, except to journalists, Red Cross representatives, and others able to show a “compelling exigency” necessitating such travel. In cases where persons did not include Ethiopia in their applications, but were — -by reason of the mention in their applications of adjacent countries — suspected of intending to travel therein, their passports were stamped “not valid for use in Ethiopia.” Ill Hackworth, su-pra, pp. 531-532. Following the outbreak of the Spanish Civil War in 1936, passports were stamped “not valid for travel in Spain,” with exceptions for newspapermen and persons furnishing medical assistance. Id., at 533-534. A similar restriction was placed on travel to China in August 1937, in view of “the disturbed situation in the Far East.” Passports were validated for travel to China only “in exceptional circumstances,” and in no case for women or children. Id., at 532-533.
[10]*10On March 31, 1938, the President, purporting to act pursuant to the 1926 Act, specifically authorized the Secretary to impose area restrictions in the issuance of passports, Exec. Order No. 7856, 3 Fed. Reg. 681, 687:
“The Secretary of State is authorized in his discretion to refuse to issue a passport, to restrict a passport for use only in certain countries, to restrict it against use in certain countries, to withdraw or cancel a passport already issued, and to withdraw a passport for the purpose of restricting its validity or use in certain countries.”
This Executive Order is still in force. 22 CFR § 51.75. In September 1939, travel to Europe was prohibited except with a passport specially validated for such travel; passports were so validated only upon a showing of the “imperativeness” of the travel. Departmental Order No. 811, 4 Fed. Reg. 3892.
Area restrictions have also been imposed on numerous occasions since World War II. Travel to Yugoslavia was restricted in the late 1940’s as a result of a series of incidents involving American citizens. Dept. State Press Conf., May 9, 1947. Travel to Hungary was restricted between December 1949 and May 1951, and after December 1951.7 In June 1951, the State Department began to stamp passports “not valid for travel in Czechoslovakia,” and declared that all passports outstanding at that time were not valid for such travel. 24 Dept. State Bull. 932. In May 1952, the Department issued a general order that all new passports would be stamped not valid for travel to Albania, Bulgaria, Communist China, Czechoslovakia, Hungary, Poland, Rumania and the Soviet Union. 26 id., at 736. In October 1955, the Secretary announced that passports would no longer require special validation [11]*11for travel to Czechoslovakia, Hungary, Poland, Rumania and the Soviet Union, but would be stamped invalid for travel “to the following areas under control of authorities with which the United States does not have diplomatic relations: Albania, Bulgaria, and those portions of China, Korea and Viet-Nam under communist control.” 33 id:, at 777. In February 1956, the restriction on travel to Hungary was reimposed. 34 id., at 246-248. And in late 1956, passports were for a brief period stamped invalid for travel to or in Egypt, Israel, Jordan and Syria. 35 id., at 756.
Even if there had been no passport legislation enacted since the 1926 Act, the post-1926 history of executive imposition of area restrictions, as well as the pre-1926 history, would be of relevance to our construction of the Act. The interpretation expressly placed on a statute by those charged with its administration must be given weight by courts faced with the task of construing the statute. Udall v. Tollman, 380 U. S. 1, 16-18; Norwegian Nitrogen Co. v. United States, 288 U. S. 294, 315. Under some circumstances, Congress’ failure to repeal or revise in the face of such administrative interpretation has been held to constitute persuasive evidence that that interpretation is the one intended by Congress.8 In this case, however, the inference is supported by more than mere congressional inaction. For in 1952 Congress, substantially re-enacting laws which had been passed during the First and Second World Wars,9 provided that after the issuance of a presidential proclamation of war or national emergency, it would be unlawful to leave or enter the [12]*12United States without a valid passport. Section 215 of the Immigration and Nationality Act of 1952, 66 Stat. 190, 8 U. S. C. § 1185 (1958 ed.). The Solicitor General urges that in view of the issuance in 1953 of a presidential proclamation of national emergency which is still outstanding,10 travel in violation of an area restriction imposed on an otherwise valid passport is unlawful under the 1952 Act. The correctness of this interpretation is a question we do not reach on this appeal, see infra, pp. 18-20. But whether or not the new legislation was intended to attach criminal penalties to the violation of area restrictions, it certainly was not meant to cut back upon the power to impose such restrictions. Despite 26 years of executive interpretation of the 1926 Act as authorizing the imposition of area restrictions, Congress in 1952, though it once again enacted legislation relating to passports, left completely untouched the broad rule-making authority granted in the earlier Act. Cf. Norwegian Nitrogen Co. v. United States, supra, at 313.11
This case is therefore not like Kent v. Dulles, supra, where we were unable to find, with regard to the sort of passport refusal involved there, an administrative practice sufficiently substantial and consistent to warrant the conclusion that Congress had implicitly approved it. [13]*13Appellant reminds us that in summarizing the Secretary’s practice in Kent, we observed:
“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 .... 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.” 357 U. S., at 127.
It must be remembered, in reading this passage, that the issue involved in Kent was whether a citizen could be denied a passport because of his political beliefs or associations. In finding that history did not support the position of the Secretary in that case, we summarized that history “so far as matérial here” — that is, so far as material to passport refusals based on the character of the particular applicant. In this case, however, the Secretary hgs refused to validate appellant’s passport not because of any characteristic peculiar to appellant, but rather because of foreign policy considerations affecting all citizens.
III.
Having concluded that the Secretary of State’s refusal to validate appellant’s passport for travel to Cuba is supported by the authority granted by Congress in the Passport Act of 1926, we must next consider whether that refusal abridges any constitutional right of appellant. Although we do not in this case reach the question of whether the 1952 Act should be read to attach criminal penalties to travel to an area for which one’s passport is not validated, we must, if we are to approach the constitutional issues presented by this appeal candidly, pro[14]*14ceed on the assumption that the Secretary’s refusal to validate a passport for a given area acts as a deterrent to travel to that area. In Kent v. Dulles, supra, at 125, we held that “ft]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.” See also Ap-theker v. Secretary of State, supra, at 505-506. However, the fact that a liberty cannot be inhibited without due process of law does not mean that it can under no circumstances be inhibited.12
The requirements of due process are a function not only of the extent of the governmental restriction imposed,13 but also of the extent of the necessity for the restriction. Cuba is the only area in the Western Hemisphere controlled by a Communist government. It is, moreover, the judgment of the State Department that a major goal of the Castro regime is to export its Communist revolution to the rest of Latin America.14 The United States and other members of the Organization of American States have determined that travel between Cuba and the other countries of the Western Hemisphere is an important element in the spreading of subversion, and many have there[15]*15fore undertaken measures to discourage such travel.15 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 to “use such means, not amounting to acts of war, as he may think necessary and proper” to secure the release of an American citizen unjustly deprived of his liberty by a foreign government,16 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.
The right to travel within the United States is of course also constitutionally protected, cf. Edwards v. California, 314 U. S. 160. But that freedom does not mean that areas ravaged by flood, fire or pestilence cannot be quarantined when it can be demonstrated that unlimited travel to the area would directly and materially interfere with [16]*16the safety and welfare of the area or the Nation as a whole. So it is with international travel. That the restriction which is challenged in this case is supported by the weightiest considerations of national security 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.
Appellant also asserts that the Secretary’s refusal to validate his passport for travel to Cuba denies him rights guaranteed by the First Amendment. His claim is different from that which was raised in Kent v. Dulles, supra, and Aptheker v. Secretary of State, supra, for the refusal to validate appellant’s passport does not result from any expression or association on his part; appellant is not being forced to choose between membership in an organization and freedom to travel. Appellant’s allegation is, rather, that the “travel ban is a direct interference with the First Amendment rights of citizens to travel abroad so that they might acquaint themselves at first hand with the effects abroad of our Government’s policies, foreign and domestic, and with conditions abroad which might affect such policies.” We must agree that the Secretary’s refusal to validate passports for Cuba renders less than wholly free the flow of information concerning that country. While we further agree that this is a factor to be considered in determining whether appellant has been denied due process of law,17 we cannot accept the contention of appellant that it is a First Amendment right which is involved. For to the extent that the Secretary’s refusal to validate passports for Cuba acts as an inhibition (and it would be unrealistic to assume that it does not), it is an inhibition of action. There are few restrictions [17]*17on action which could not be clothed by ingenious argument in the garb of decreased data flow. For example, the prohibition of unauthorized entry into the White House diminishes the citizen’s opportunities to gather information he might find relevant to his opinion of the way the country is being run, but that does not make entry into the White House a First Amendment right. The right to speak and publish does not carry with it the unrestrained right to gather information.
Finally, appellant challenges the 1926 Act on the ground that it does not contain sufficiently definite standards for the formulation of travel controls by the Executive. It is important to bear in mind, in appraising this argument, that because of the changeable and explosive nature of contemporary international relations, and the fact that the Executive is immediately privy to information which cannot be swiftly presented to, evaluated by, and acted upon by the legislature, 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.
“Practically every volume of the United States Statutes contains one or more acts or joint resolutions of Congress authorizing action by the President in respect of subjects affecting foreign relations, which either leave the exercise of the power to his unrestricted judgment, or provide a standard far more general than that which has always been considered requisite with regard to domestic affairs.” United States v. Curtiss-Wright Corp., 299 U. S. 304, 324.
This does not mean that simply because a statute deals with foreign relations, it can grant the Executive totally unrestricted freedom of choice. However, the 1926 Act contains no such grant. We have held, Kent v. Dulles, supra, and reaffirm today, that the 1926 Act must take its [18]*18content from history: it authorizes only those passport refusals and restrictions “which it could fairly be argued were adopted by Congress in light of prior administrative practice.” Kent v. Dulles, supra, at 128. So limited, the Act does not constitute an invalid delegation.
IV.
Appellant’s complaint sought not only an order compelling the Secretary of State to validate his passport for travel to Cuba, but also a declaration that appellant “is entitled under the Constitution and laws of the United States to travel to Cuba,” and an order enjoining the Secretary and the Attorney General from interfering with such travel. Read in the context of the arguments appellant makes here, it appears that the intent of the complaint was that these latter prayers should be considered only in the event that the court decided that the Secretary lacks authority to refuse to validate appellant’s passport for Cuba. However, the complaint can- also be read to incorporate a request that, even if the court should find that the Secretary does have such authority, it go on to decide whether appellant can be criminally prosecuted, under § 215 (b) of the Immigration and Nationality Act of 1952, 66 Stat. 190, 8 U. S. C. § 1185 (b) (1958 ed.), for travel in violation of an area restriction. That section provides:
“After such proclamation as is provided for in subsection (a) has been made and published and while such proclamation is in force, it shall, except as otherwise provided by the President, and subject to such limitations and exceptions as the President may authorize and prescribe, be unlawful for any citizen of the United States to depart from or enter, or attempt to depart from or enter, the United States unless he bears a valid passport.”
[19]*19A proclamation of the sort referred to was issued in 1953 and remains on the books. Pres. Proc. No. 3004, 67 Stat. c31; cf. Exec. Order No. 11037, 3 CFR 621 (1959-1963 Comp.). We hold that on either interpretation of the complaint, the court below was correct in refusing to reach the issue of criminal liability.
There are circumstances under which courts properly make exceptions to the general rule that equity will not interfere with the criminal processes, by entertaining actions for injunction or declaratory relief in advance of criminal prosecution. See Evers v. Dwyer, 358 U. S. 202; Terrace v. Thompson, 263 U. S. 197. However, the Declaratory Judgment Act, 28 U. S. C. § 2201 (1958 ed.), “is an enabling Act, which confers a discretion on the courts rather than an absolute right upon the litigant.” Public Serv. Comm’n v. Wycoff Co., 344 U. S. 237, 241. The complaint filed in this case does not specify the sort of travel to Cuba appellant has in mind — e. g., whether he plans to proceed to Cuba directly or travel there via one or more other countries. Nor can we tell from the papers filed whether the Government will, in the event appellant journeys to Cuba, charge him under § 215 (b) with leaving the United States on a carrier bound for Cuba with a passport not validated for Cuba; leaving the United States with such a passport with the intent of traveling to Cuba before he returns home; leaving the United States with such a passport on a journey which in fact takes him to Cuba; re-entering the United States with such a passport after having visited Cuba; some other act — or whether it will charge him at all.18 Whether [20]*20each or any of these gradations of fact or charge would make a difference as to criminal liability is an issue on which the District Court wisely took no position. Nor do we. For if we are to avoid rendering a series of advisory opinions, adjudication of the reach and constitutionality of § 215 (b) must await a concrete fact situation. Compare Federation of Labor v. McAdory, 325 U. S. 450.
The District Court therefore correctly dismissed the complaint, and its judgment is
Affirmed.