Opinion

JUSTICE O'CONNOR delivered the opinion of the Court.

The question presented is whether respondent may be convicted for violating 18 U.S.C. § 1382, which makes it unlawful to reenter a military base after having been barred by the commanding officer. Respondent attended an open house at a military base some nine years after the commanding officer ordered him not to reenter without written permission. The Court of Appeals for the Ninth Circuit held that respondent could not be convicted for violating § 1382 because he had a First Amendment right to enter the military base during the open house. 710 F.2d 1410 (1983). We granted certiorari, 469 U.S. 1071 (1984), and we now reverse.

I

The events underlying this case date from 1972, when respondent and a companion entered Hickam Air Force Base (Hickam) in Hawaii ostensibly to present a letter to the commanding officer. Instead, they obtained access to secret Air Force documents and destroyed the documents by pouring animal blood on them. For these acts, respondent was convicted of conspiracy to injure Government property in violation of 18 U.S.C. §§ 371, 1361. Respondent also received a "bar letter" from the Commander of Hickam informing him that he was forbidden to

reenter the confines of this installation without the written permission of the Commander or an officer designated by him to issue a permit of reentry.

App. 43; cf. Greer v. Spock, 424 U. S. 828, 424 U. S. 838 (1976). The bar letter directed respondent to 18 U.S.C. § 1382 and quoted the statute, which provides:

Whoever, within the jurisdiction of the United States, goes upon any military, naval, or Coast Guard Reservation, post, fort, arsenal, yard, station, or installation, for any purpose prohibited by law or lawful regulation; or Whoever reenters or is found within any such reservation, post, fort, arsenal, yard, station, or installation,after having been removed therefrom or ordered not to reenter by any officer in command or charge thereof - Shall be fined not more than $500 or imprisoned not more than six months, or both.

In subsequent years, respondent, according to his own testimony, received bar letters from a number of military bases in Hawaii. App. 30. In March, 1981, he and eight companions improperly entered the Nuclear War Policy and Plans Office at Camp Smith in Hawaii and defaced Government property. Ibid. Respondent testified that he was not prosecuted for what he termed his "rather serious clear-cut case" of civil disobedience at Camp Smith, ibid., and that the 1972 bar letter was the only one he had ever received for Hickam. Id. at 28, 30.

Respondent entered Hickam again on May 16, 1981, during the base's annual open house for Armed Forces Day. On that day, members of the public, who ordinarily can enter Hickam only with permission, are allowed to enter portions of the base to view displays of aircraft and other military equipment and to enjoy entertainment provided by military and nonmilitary performers. Press releases issued by the base declared that,

[w]hile Hickam is normally a closed base, the gates will be open to the public for this 32nd Annual Armed Forces Day Open House.

Id. at 45. Radio announcements similarly proclaimed that "the public is invited, and it's all free." Id. at 48.

With four friends, respondent attended the open house in order to engage in a peaceful demonstration criticizing the nuclear arms race. Id. at 27-28. His companions gathered in front of a B-52 bomber display, unfurled a banner reading "Carnival of Death," and passed out leaflets. Respondent took photographs of the displays, and did not disrupt the activities of the open house. The Commander of Hickam summoned Major Jones, the Chief of Security Police at the base, and told him to have the individuals cease their demonstration. Id. at 9. Before respondent was approached by military police, the Commander further informed Major Jones that he believed one of the individuals involved in the demonstration had been barred from Hickam. Id. at 9-10, 13-14. Respondent and his companions were apprehended and escorted off the base.

An information filed on July 1, 1981, charged respondent with violating § 1382 because, on May 16, 1981, he "unlawfully and knowingly" reentered Hickam Air Force Base "after [he] had previously been ordered not to reenter by an officer in command." Id. at 3. Respondent was convicted after a bench trial and sentenced to three months' imprisonment. Id. at 1. On appeal, respondent challenged his conviction on three grounds. 710 F.2d at 1413. First, he argued that he had written permission to reenter based on the advertisements inviting the public to attend the open house. Second, respondent contended that the 9-year-old bar letter was ineffective, because it violated due process. Finally, he argued that his presence at Hickam during the open house was protected by the First Amendment. The Court of Appeals rejected respondent's first argument and found it unnecessary to consider the due process arguments. Id. at 1413, 1417. The conviction must be reversed, the Court of Appeals held, because Hickam had been transformed into a temporary public forum during the open house, and the military could not exclude respondent from such a forum. Id. at 1417.

II

In the order granting certiorari, this Court asked the parties to address the additional question

[w]hether the respondent's attendance at the 'open house' at Hickam Air Force Base on May 16, 1981, was the kind of reentry that Congress intended to prohibit in 18 U.S.C. § 1382.

469 U.S. at 1071. Although this issue was not raised by the parties or passed upon by the Court of Appeals, we address it to

'ascertain whether a construction of the statute is fairly possible by which the [constitutional] question may be avoided.'

United States v. Grace, 461 U. S. 171, 461 U. S. 175 -176 (1983), quoting Crowell v. Benson, 285 U. S. 22, 285 U. S. 62 (1932).

Courts in applying criminal laws generally must follow the plain and unambiguous meaning of the statutory language. Garcia v. United States, 469 U. S. 70, 469 U. S. 75 (1984); United States v. Turkette, 452 U. S. 576, 452 U. S. 580 (1981). "[O]nly the most extraordinary showing of contrary intentions" in the legislative history will justify a departure from that language. Garcia, supra, at 469 U. S. 75. This proposition is not altered simply because application of a statute is challenged on constitutional grounds. Statutes should be construed to avoid constitutional questions, but this interpretative canon is not a license for the judiciary to rewrite language enacted by the legislature. Heckler v. Mathews, 465 U. S. 728, 465 U. S. 741 -742 (1984). Any other conclusion, while purporting to be an exercise in judicial restraint, would trench upon the legislative powers vested in Congress by Art. I, § 1, of the Constitution. United States v. Locke, 471 U. S. 84, 471 U. S. 95 -96 (1985). Proper respect for those powers implies that

[s]tatutory construction must begin with the language employed by Congress and the assumption that the ordinary meaning of that language accurately expresses the legislative purpose.

Park 'N Fly v. Dollar Park and Fly, Inc., 469 U. S. 189, 469 U. S. 194 (1985).

Turning to the statute involved here, we conclude that § 1382 applies to respondent's conduct. The relevant portion of the statute makes it unlawful for a person to reenter a military base after having been ordered not to do so by the commanding officer. Unless the statutory language is to be emptied of its ordinary meaning, respondent violated the terms of § 1382 when he reentered Hickam in 1981 contrary to the bar letter. Respondent, however, argues that § 1382 does not apply to his attendance at the open house for three reasons. First, he contends that § 1382 does not allow indefinite exclusion from a military base, but instead applies only when a person has reentered "within a reasonable period of time after being ejected." Brief for Respondent 10. Second, respondent maintains that Congress did not intend § 1382 to apply when a military base is opened to the general public for purposes of attending an open house. Respondent finally argues that reentry is unlawful under § 1382 only if a person knows that his conduct violates an extant order not to return. None of these arguments is persuasive.

The legislative history of § 1382, although sparse, fully supports application of the statute to respondent. The statute was enacted in virtually its present form as part of a general revision and codification of the federal penal laws. Act of Mar. 4, 1909, ch. 321, § 45, 35 Stat. 1097. Both the War Department and the Department of Justice supported the statute as an extension of existing prohibitions on sabotage. The congressional Reports explained:

[I]t... is designed to punish persons who, having been ejected from a fort, reservation, etc., return for the purpose of obtaining information respecting the strength, etc., of the fort, etc., or for the purpose of inducing the men to visit saloons, dives, and similar places. Such persons may now go upon forts and reservations repeatedly for such purposes, and there is no law to punish them.

S.Rep. No. 10, 60th Cong., 1st Sess., pt. 1, p. 16 (1908); H.R.Rep. No. 2, 60th Cong., 1st Sess., pt. 1, p. 16 (1908).

The congressional Reports, as well as the floor debates, 42 Cong.Rec. 689 (1908) (remarks of Reps. Moon and Williams), indicate that the primary purpose of § 1382 was to punish spies and panderers for repeated entry into military installations. Nonetheless, § 1382, by its terms, is not limited to such persons, and such a restrictive reading of the statute would frustrate its more general purpose of "protect[ing] the property of the Government so far as it relates to the national defense." 42 Cong.Rec. 689 (1908) (remarks of Reps. Moon and Payne). One need hardly strain to conclude that this purpose is furthered by applying § 1382 to respondent, who has repeatedly entered military installations unlawfully and engaged in vandalism against Government property.

We find no merit to the reasons respondent offers for concluding he did not violate § 1382. First, nothing in the statute or its history supports the assertion that § 1382 applies only to reentry that occurs within some "reasonable" period of time. Respondent argues that most prosecutions for violating the second paragraph of § 1382 have involved reentry within a year after issuance of a bar order, and further asserts that recent bar letters for Hickam have been limited to a 1or 2-year period. We agree that prosecution under § 1382 would be impermissible if based on an invalid bar order. But even assuming the accuracy of respondent's description of prosecutorial and military policy, we do not believe that it justifies engrafting onto § 1382 a judicially defined time limit. Although due process or military regulations might limit the effective lifetime of a bar order, § 1382, by its own terms, does not limit the period for which a commanding officer may exclude a civilian from a military installation.

Section 1382, we further conclude, applies during an open house. Of course, Congress in 1909 very likely gave little thought to open houses on military bases. The pertinent question, however, is whether § 1382 applies to a base that is open to the general public. The language of the statute does not limit § 1382 to military bases where access is restricted. Moreover, the legislative intent to punish panderers and others who repeatedly enter military facilities suggests that Congress was concerned with bases that are to some extent open to nonmilitary personnel. Finally, limiting the prohibition on reentry to closed military bases would make the second paragraph of § 1382 almost superfluous, because the first paragraph of the statute already makes it unlawful for a person to go upon a military installation "for any purpose prohibited by law or lawful regulation." 18 U.S.C. § 1382. Cf. Heckler v. Chaney, 470 U. S. 821, 470 U. S. 829 (1985) (noting common-sense principle that a statute is to be read to give effect to each of its clauses).

The final statutory argument advanced by respondent is that he did not violate § 1382 because he did not subjectively believe that his attendance at the open house was contrary to a valid order barring reentry. This argument misperceives the knowledge required for a violation of the statute. Cf. United States v. Parrilla Bonilla, 648 F.2d 1373, 1377 (CA1 1981) (specific intent to violate particular regulation not required for violation of first paragraph of § 1382). The second paragraph of § 1382 does not contain the word "knowingly" or otherwise refer to the defendant's state of mind, and there is no requirement that the Government prove improper motive or intent. Holdridge v. United States, 282 F.2d 302, 310-311 (CA8 1960). Respondent does not dispute that he received the bar letter in 1972 and deliberately and knowingly reentered the base to which the letter applied. Nothing in the language of § 1382 or in previous judicial decisions supports the rather remarkable proposition that, merely because respondent thought the bar order was no longer effective, he was thereby immunized from prosecution. Cf. United States v. International Minerals & Chemical Corp., 402 U. S. 558, 402 U. S. 563 (1971).

We also reject the suggestion, made in the dissenting opinion, that § 1382 does not apply because the circumstances did not reasonably indicate to respondent that his reentry during the open house was prohibited. Post at 472 U. S. 696 -697, 472 U. S. 701. The assertion that respondent lacked notice that his entry was prohibited is implausible. The bar letter in no way indicated that it applied only when public access to Hickam was restricted. Any uncertainty respondent had in this regard might have been eliminated had he sought, in accord with the bar letter, permission to reenter from the base commander. There is no contention that respondent ever asked to have the bar letter rescinded or otherwise requested permission to reenter the base. Moreover, the dissenting opinion exaggerates the implications of our holding. We have no occasion to decide in what circumstances, if any, § 1382 can be applied where anyone other than the base commander has validly ordered a person not to reenter a military base. Nor do we decide or suggest that the statute can apply where a person unknowingly or unwillingly reenters a military installation. Finally, we note that respondent has not disputed that he entered a portion of Hickam that was a "military reservation, army post fort, or arsenal" within the meaning of § 1382.

III

The Court of Appeals held that the First Amendment bars respondent's conviction for violating § 1382. A military base, the court acknowledged, is ordinarily not a public forum for First Amendment purposes even if it is open to the public. See Greer v. Spock, 424 U. S. 828 (1976). Nonetheless, the court relied on Flower v. United States, 407 U. S. 197 (1972) (per curiam), to conclude that portions of Hickam constituted at least a temporary public forum because the military had opened those areas to the public for purposes related to expression. 710 F.2d at 1414-1417. Having found that the public had a First Amendment right to hold signs and to distribute leaflets at Hickam on Armed Forces Day, the Court of Appeals then considered whether the military could rely on the bar letter to exclude respondent from the base. Id. at 1417. The court, again relying on Flower, held that the military lacks power to exclude persons from a military base that has become a public forum. 710 F.2d at 1417.

In holding that § 1382 cannot be applied during an open house, the Court of Appeals misapprehended the significance of Flower. As this Court later observed in Greer, the decision in Flower must be viewed as an application of established First Amendment doctrine concerning expressive activity that takes place in a municipality's open streets, sidewalks, and parks. 424 U.S. at 424 U. S. 835 -836. Flower did not adopt any novel First Amendment principles relating to military bases, but instead concluded that the area in question was appropriately considered a public street. There is "no generalized constitutional right to make political speeches or distribute leaflets," id. at 424 U. S. 838, on military bases, even if they are generally open to the public. Id. at 424 U. S. 830, 424 U. S. 838, and n. 10. Greer clarified that the significance of the per curiam opinion in Flower is limited by the unusual facts underlying the earlier decision. 424 U.S. at 424 U. S. 837.

The Court in Flower summarily reversed a conviction under § 1382 of a civilian who entered a military reservation after receiving a bar letter. At the time of his arrest, the civilian was "quietly distributing leaflets on New Braunfels Avenue at a point within the limits of Fort Sam Houston" in San Antonio, Texas. 407 U.S. at 407 U. S. 197. No sentry was posted anywhere along the street, which was open to unrestricted civilian traffic 24 hours a day. Id. at 407 U. S. 198. The Court determined that New Braunfels Avenue was a public thoroughfare no different than other streets in the city, and that the military had abandoned not only the right to exclude civilian traffic from the avenue, but also any right to exclude leafleteers. Greer v. Spock, supra, at 424 U. S. 835. The defendant in Flower received a bar letter because he participated in an attempt to distribute unauthorized publications on the open military base. 407 U.S. at 407 U. S. 197 ; United States v. Flower, 452 F.2d 80, 82, 87 (CA5 1971). This was the very activity that Flower held protected by the First Amendment.

Flower cannot plausibly be read to hold that regardless of the events leading to issuance of a bar letter, a person may not subsequently be excluded from a military facility that is temporarily open to the public. Instead, Flower establishes that where a portion of a military base constitutes a public forum because the military has abandoned any right to exclude civilian traffic and any claim of special interest in regulating expression, see Greer v. Spock, supra, at 424 U. S. 836 -838, a person may not be excluded from that area on the basis of activity that is itself protected by the First Amendment. Properly construed, Flower is simply inapplicable to this case. There is no suggestion that respondent's acts of vandalism in 1972, which resulted in the issuance of the bar letter, were activities protected by the First Amendment. The observation made by the Court of Appeals, 710 F.2d at 1417, that enforcement of the bar letter was precipitated by respondent's "peaceful expressive activity" misses the point. Respondent was prosecuted not for demonstrating at the open house, but for reentering the base after he had been ordered not to do so.

Respondent argues that, because Hickam was temporarily transformed into a public forum, the exercise of standardless discretion by the base commander to exclude him from the base violates the First Amendment. Cf. Shuttlesworth v. Birmingham, 394 U. S. 147, 394 U. S. 150 -151 (1969). The conclusion of the Court of Appeals that Hickam was ever a public forum is dubious. Military bases generally are not public fora, and Greer expressly rejected the suggestion that

whenever members of the public are permitted freely to visit a place owned or operated by the Government, then that place becomes a 'public forum' for purposes of the First Amendment.

424 U.S. at 424 U. S. 836. See also United States v. Grace, 461 U.S. at 461 U. S. 177. Nor did Hickam become a public forum merely because the base was used to communicate ideas or information during the open house. United States Postal Service v. Greenburgh Civic Assns., 453 U. S. 114, 453 U. S. 130, n. 6 (1981). The District Court did not make express findings on the nature of public access to Hickam during the open house, and the record does not suggest that the military so completely abandoned control that the base became indistinguishable from a public street as in Flower.

Whether or not Hickam constituted a public forum on the day of the open house, the exclusion of respondent did not violate the First Amendment. Respondent concedes that the commander of Hickam could exclude him from the closed base, but contends this power was extinguished when the public was invited to enter on Armed Forces Day. We do not agree that "the historically unquestioned power of a commanding officer to exclude civilians from the area of his command," Cafeteria Workers v. McElroy, 367 U. S. 886, 367 U. S. 893 (1961), should be analyzed in the same manner as government regulation of a traditional public forum simply because an open house was held at Hickam. See Greer v. Spock, 424 U.S. at 424 U. S. 838, n. 10 (fact that speakers previously allowed on base "did not leave the authorities powerless thereafter to prevent any civilian from entering... to speak on any subject whatever"). The fact that respondent had previously received a valid bar letter distinguished him from the general public and provided a reasonable grounds for excluding him from the base. That justification did not become less weighty when other persons were allowed to enter. Indeed, given the large number of people present during an open house, the need to preserve security by excluding those who have previously received bar letters could become even more important, because the military may be unable to monitor closely who comes and goes. Where a bar letter is issued on valid grounds, a person may not claim immunity from its prohibition on entry merely because the military has temporarily opened a military facility to the public.

Section 1382 is content-neutral and serves a significant Government interest by barring entry to a military base by persons whose previous conduct demonstrates that they are a threat to security. Application of a facially neutral regulation that incidentally burdens speech satisfies the First Amendment if it

furthers an important or substantial governmental interest; if the governmental interest is unrelated to the suppression of free expression; and if the incidental restriction on alleged First Amendment freedoms is no greater than is essential to the furtherance of that interest.

United States v. O'Brien, 391 U. S. 367, 391 U. S. 377 (1968). Respondent argues that even if O'Brien applies here, the general exclusion of recipients of bar letters from military open houses fails under the First Amendment because it is greater than is essential to the furtherance of Government interests in the security of military installations.

Respondent maintains that enforcing bar letters is not essential to security because reported cases concerning § 1382 have not involved vandalism or other misconduct during open houses. Moreover, respondent asserts that persons holding bar letters have been allowed to attend open houses on bases other than Hickam. Finally, respondent contends that the Government interests were adequately served by the security measures taken during the open house and by statutes that punish any misconduct occurring at such events. Cf. 710 F.2d at 1417 (noting that "sensitive areas of Hickam were cordoned off and protected by guards"). Respondent's arguments in this regard misapprehend the third element of the O'Brien standard. We acknowledge that barring respondent from Hickam was not "essential" in any absolute sense to security at the military base. The military presumably could have provided him with a military police chaperone during the open house. This observation, however, provides an answer to the wrong question by focusing on whether there were conceivable alternatives to enforcing the bar letter in this case.

The First Amendment does not bar application of a neutral regulation that incidentally burdens speech merely because a party contends that allowing an exception in the particular case will not threaten important government interests. See Clark v. Community for Creative Non-Violence, 468 U. S. 288, 468 U. S. 296 -297 (1984) ("the validity of this regulation need not be judged solely by reference to the demonstration at hand"). Regulations that burden speech incidentally or control the time, place, and manner of expression, see id. at 468 U. S. 298 -299, and n. 8, must be evaluated in terms of their general effect. Nor are such regulations invalid simply because there is some imaginable alternative that might be less burdensome on speech. Id. at 468 U. S. 299. Instead, an incidental burden on speech is no greater than is essential, and therefore is permissible under O'Brien, so long as the neutral regulation promotes a substantial government interest that would be achieved less effectively absent the regulation. Cf. 468 U.S. at 468 U. S. 297 ("if the parks would be more exposed to harm without the sleeping prohibition than with it, the ban is safe from invalidation under the First Amendment"). The validity of such regulations does not turn on a judge's agreement with the responsible decisionmaker concerning the most appropriate method for promoting significant government interests. Id. at 468 U. S. 299.

We are persuaded that exclusion of holders of bar letters during military open houses will promote an important Government interest in assuring the security of military installations. Nothing in the First Amendment requires military commanders to wait until persons subject to a valid bar order have entered a military base to see if they will conduct themselves properly during an open house. Cf. Perry Ed. Assn. v. Perry Local Educators' Assn., 460 U. S. 37, 460 U. S. 52, and n. 12 (1983). In Community for Creative Non-Violence, we observed that O'Brien does not

assign to the judiciary the authority to replace the Park Service as the manager of the Nation's parks or endow the judiciary with the competence to judge how much protection of park lands is wise and how that level of conservation is to be attained.

468 U.S. at 468 U. S. 299 (footnote omitted). We are even less disposed to conclude that O'Brien assigns to the judiciary the authority to manage military facilities throughout the Nation.

As a final First Amendment challenge to his conviction, respondent asserts that the Government apprehended and prosecuted him because it opposed the demonstration against nuclear war. This argument lacks evidentiary support. The demonstration did attract the attention of military officials to respondent and his companions, and the base Commander ordered military police to stop them from displaying their banner and distributing leaflets. Nonetheless, Major Jones testified that respondent was not approached or apprehended until he was identified as the possible holder of a bar letter. App. 9-11, 13-14. The trial judge found that this testimony was accurate, Tr. 98, and we see no reason to disturb that finding on appeal. Inasmuch as respondent contends that his prosecution was impermissibly motivated, he did not raise below, and the record does not support, a claim that he was selectively prosecuted for engaging in activities protected by the First Amendment. Cf. Wayte v. United States, 470 U. S. 598, 470 U. S. 608 -610 (1985).

IV

Before the District Court and the Court of Appeals, respondent argued that his prosecution based on the 1972 bar letter violated due process. Respondent has made similar arguments to this Court. Brief for Respondent 19, 20, 26-27, n. 38. Although a commanding officer has broad discretion to exclude civilians from a military base, this power cannot be exercised in a manner that is patently arbitrary or discriminatory. Cafeteria Workers v. McElroy, 367 U.S. at 367 U. S. 898. Respondent, however, has not shown that the 1972 bar letter is inconsistent with any statutory or regulatory limits on the power of military officials to exclude civilians from military bases. Nor do we think that it is inherently unreasonable for a commanding officer to issue a bar order of indefinite duration requiring a civilian to obtain written permission before reentering a military base. The Court of Appeals did not address whether, on the facts of this case, application of the 1972 bar letter to respondent was so patently arbitrary as to violate due process, and we therefore do not decide that issue.

For the reasons stated, the judgment of the Court of Appeals is reversed, and the case is remanded for further proceedings consistent with this opinion.

It is so ordered.