Mr. Justice Douglas
delivered the opinion of the Court.
Section 20 of the Immigration Act of 1917, as amended, 39 Stat. 890, 57 Stat. 553, 64 Stat. 1010, 8 U. S. C. (Supp. IV) § 156, contains provisions designed to expedite the deportation of aliens. Section 20 (a) provides that the Attorney General shall direct the deportation “to the country specified by the alien, if it is willing to accept him into its territory.” Otherwise the Attorney General shall direct the deportation to any one of a series of specified countries or if deportation to any of them is impracticable, inadvisable, or impossible, then to any country which is willing to accept the alien. Section 20 (b) grants the Attorney General powers of supervision over aliens against whom deportation orders have been outstanding for more than six months and fixes penalties for violations of the regulations which the Attorney General has prescribed. Section 20 (c) provides that any alien against whom a specified order of deportation is outstanding “who shall willfully fail or refuse to depart from the United States within a period of six months from the date of such order of deportation, or from the date of the enactment of the Subversive Activities Control Act of 1950, whichever is the later, or shall willfully fail or refuse to make timely application in good faith for travel or other documents necessary to his departure, . . . shall upon conviction be guilty of a felony, and shall be imprisoned not more than ten years . . . .” (Italics added.)
The latter (the italicized) provision of § 20 (c) is involved here. Appellee is an alien who came to this country from Russia in 1913. An order of deportation was entered against him in 1930 by reason of his advocacy of the overthrow of the Government by force and violence. An indictment was returned against him, two counts of which charged him with willfully failing and refusing to make timely application in good faith for travel or other documents necessary to his departure from the United States. The District Court sustained a motion to dismiss these two counts. It held that the statute in question was unconstitutionally vague and indefinite, because it did not specify the nature of the travel documents necessary for departure nor indicate to which country or to how many countries the alien should make application. 99 F. Supp. 778. The case is here on appeal. 18 U. S. C. (Supp. IV) § 3731.
While a statute, plain and unambiguous on its face, may be given an application that violates due process of law, we are not concerned with that problem in the present case. The question here is whether the statute on its face meets the constitutional test of certainty and definiteness. We think it does when viewed in its statutory setting.
The statutory scheme seems clear and unambiguous. The choice of a country willing to receive the alien is left first to the alien himself and then to the Attorney General. Once the country willing to receive the alien is identified, the mechanism for effecting his departure remains. The six-month period specified in § 20 (c) makes clear what a “timely” application is. The statutory words “travel or other documents necessary to his departure” will, of course, have different meanings in reference to various countries. The forms to be filled out, the deposits to be made, the number of photographs to be furnished, and the information to be supplied will vary from country to country. But when the country to which the alien is to be deported is known, any mystery concerning the documents necessary to his departure vanishes. The words “necessary to his departure” when applied to deportations would normally refer to a lawful departure from this country and a lawful entrance into another. The alien satisfies the statute by making timely application for such documents as the country in question requires for his admission.
The statute might well be a trap if, for example, it required the alien to know the visa requirements of one or more countries. But the emphasis of the present statute is on a “timely application in good faith” for such documents as the country in question may require. Though the visa requirements for entrance into a particular country are in constant change, the command of the statute remains simple and intelligible. We conclude that the warning contained in the statute is sufficiently definite to free it of any constitutional infirmity of vagueness. Cf. United States v. Petrillo, 332 U. S. 1; Jordan v. De George, 341 U. S. 223.
Another question of constitutional law is pressed upon us. It is that the statute must be declared unconstitutional because it affords a defendant no opportunity to have the court which tries him pass on the validity of the order of deportation. That question was neither raised by the appellee nor briefed nor argued here. If it had been, we might consider it. See United States v. Curtiss-Wright Corp., 299 U. S. 304, 330. But when a single, naked question of constitutionality is presented, we do not search for new and different constitutional questions. Rather we refrain from passing on the constitutionality of a phase of a statute until a stage has been reached where the decision of the precise constitutional issue is necessary. See United States v. Petrillo, supra.
It will be time to consider whether the validity of the order of deportation may be tried in the criminal trial either by the court or by the jury (cf. Yakus v. United States, 321 U. S. 414; Cox v. United States, 332 U. S. 442) when and if the appellee seeks to have it tried. That question is not foreclosed by this opinion. We reserve decision on it.
Reversed.
Mr. Justice Clark took no part in the consideration or decision of this case.