Kristine Vasarajs appeals her conviction, following a trial by a magistrate which was affirmed by a district court, for unlawful reentry onto a military reservation in violation of 18 U.S.C. § 1382. 1 Vasarajs con *445 tends that the district court erred in confirming the magistrate’s determination that she violated 18 U.S.C. § 1382 by knowingly crossing an identifiable border of a military reservation from which she had been barred. She argues that she did not have fair notice of the boundary of the reservation and that she did not willingly enter the main gate when required to do so by military police. We affirm appellant’s conviction.
I
On or about July 18, 1984, Colonel Victor E. Micol, Jr., as post commander, issued a barment letter indefinitely forbidding Vasarajs from returning to Fort Richardson (“the Fort”) because of past misconduct involving illegal drugs on the Fort. Vasa-rajs received this letter, which stated in part that “[u]pon receipt of this letter, you are ordered not to reenter or be found within the limits of Fort Richardson, Alaska.” It further warned that should Vasarajs reenter she would be subject to prosecution under 18 U.S.C. § 1382.
Fort Richardson, a military reservation occupying a large area north of Anchorage, Alaska, is bisected by Glenn Highway (“the highway”), a public divided highway. On March 14, 1987, Vasarajs turned off the highway and approached the main gate at the Fort for the purpose of driving two passengers to an organized dance being held on the base. On the access road, while approaching the main gate, Vasarajs passed one sign stating “Welcome to Fort Richardson,” and a second warning “You are now entering a military reservation, you are subject to search at any time.” Upon approaching the gate, Vasarajs observed that a search of other ears was in progress and changed her mind about entering the Fort. At the gate, Vasarajs indicated that she did not want to enter, but was told that she would have to pass the guard shack for inspection. She was directed to a second gate for a search.
On March 23, 1987, the Special Assistant United States Attorney filed an information charging Vasarajs with entry upon a military reservation after being ordered not to return in violation of 18 U.S.C. § 1382. Vasarajs was tried before a United States magistrate and found guilty. She was sentenced to pay a fine of $300, conditioned upon not committing a similar offense for a period of one year; $250 of the fine was suspended. On appeal, the United States District Court for the District of Alaska affirmed and imposed a special assessment fee pursuant to 18 U.S.C. § 3013. Vasa-rajs timely appeals.
II
The magistrate found Vasarajs guilty of unlawful entry. Based upon testimony that the boundary of Fort Richardson extends to the edge of the highway, the magistrate concluded that Vasarajs had already entered the Fort when she changed her mind and requested to leave. The district court agreed. Vasarajs’ primary contention on appeal is that she did not realize she had entered Fort Richardson prior to reaching the guard shack. She builds what in effect are two separate arguments around this contention. The first is that the United States, despite holding title to the land extending from the guard shack out to the highway, ceded control of this property to the public at large and thus cannot exclude anyone from this .area. The second argument is that due process requires that a person entering a military reservation be provided with objectively reasonable notice of the boundaries of the reservation. We address each argument in turn.
A
Vasarajs argues that because the public is allowed to traverse that portion of road between the end of the exit ramp off the highway and the guard shack, the government has relinquished its control *446 over this area despite its legal title to the land; ' We disagree.
As an initial matter, we are reluctant to agree that the government’s failure to exercise visible control over its property necessarily results in an inability to exclude others or use.the property in any way it sees fit. Appellant’s theory seems to be that lack of control leads directly to a loss of the
right
to control. To be sure, a line of cases suggests that the fact that the United States has title to land contained within a reservation is insufficient to prove that the land is part of the reservation. But these cases merely stand for the uncontroversial proposition that record title does not unfailingly denote the title holder’s “absolute ownership, or an exclusive right to the possession” of the property in question,
United States v. Watson,
Significantly, Vasarajs has never argued that either she in particular or the public at large benefits from a properly created easement burdening the portion of roadway in question. 3 Nor has she ever maintained that either she in particular or the public in general gained title to this disputed property by means of adverse possession 4 or an implied *447 dedication. 5
Nevertheless, there appears to be some authority for the proposition that the government must exercise control over its property in order to preserve the right to exclude others from it pursuant to § 1382. Dictum in
United States v. Albertini,
Nothing in the record indicates that the government has failed to exercise control over that portion of the Fort on the access road and extending from the guard shack out to the highway. To the contrary, the two signs standing along the side of this disputed stretch of road constitute sufficient evidence of military control, particularly the one warning drivers that “you are subject to search at any time.”
B
Vasarajs also alleges that she mistakenly believed the boundary of the Fort to be the guard shack and thus did not realize she had entered the Fort upon leaving the highway. She does not build a mistake of fact or law defense around this contention, however. 7 Instead, she claims *448 that she did not have fair notice of the boundary of Fort Richardson. 8 As such, Vasarajs’ argument taps into the requirement that citizens be provided clear notice of that conduct which is criminally punishable.
As a general matter, the so-called “legality principle” mandates that “conduct is not criminal unless forbidden by law which gives advance warning that such conduct is criminal.” 1 W. LaFave & A. Scott,
Substantive Criminal Law
§ 3.1, at 271 (1986);
see also Lambert v. California,
The void-for-vagueness doctrine springs from the legality principle,
see
1 W. LaFave & A. Scott,
supra,
§ 3.1, at 272, and effectively holds that the very words of statutes must be sufficiently precise to provide comprehensible notice to average citizens of the substance of the rules that bind them.
See id.
§ 2.3. The Supreme Court has stated that “because we assume that man is
*449
free to steer between lawful and unlawful conduct, we insist that laws give the person of ordinary intelligence a reasonable opportunity to know what is prohibited, so that he may act accordingly. Vague laws trap the innocent by not providing fair warning.”
Grayned v. City of Rockford,
The legality principle obviously has been satisfied in this case because Vasarajs’ bar order was not only “published,” but sent directly to her as well. 10 In short, we need not deem her to have had constructive notice of the bar letter, for it is clear that she had actual notice of the fact that she was forbidden to reenter the Fort. Similarly, the use of the term “Fort Richardson” in the bar order at issue is not so inherently vague as to make the order void-for-vagueness. Yet Vasarajs in effect argues that due process is also implicated because she was not given sufficient warning of the geographical boundaries of the Fort.
Extrapolating from the legality principle and the void-for-vagueness doctrine, we agree that due process requires that there have been some way for Vasarajs to learn the boundary of the Fort. But this probably does not mean that the government had to provide actual notice to Vasarajs. The possibility that an official description of the Fort’s geographical boundaries was available to Vasarajs had she made inquiry of the government would likely satisfy the dictates of due process. Nonetheless, we need not determine the exact parameters demanded by due process in this case because the facts establish that actual notice of the entrance of Fort Richardson was provided to Vasarajs. We hold that the signs posted along the access road leading up to the guard shack adequately announced themselves to Vasarajs as the dividing line between the highway and the Fort. One sign said “Welcome to Fort Richardson,” not “Fort Richardson up ahead.” The second sign quite bluntly said “You are now entering a military reservation, you are subject to search at any time ” (emphasis added). These signs provided reasonable notice that Vasarajs had left behind civilian territory prior to reaching the guard shack.
C
In light of our determination that Vasa-rajs had sufficient notice of the Fort’s boundary, her contention that she unwillingly passed the guard gate becomes a moot point. For she had already completed her violation of § 1382 when she was ordered to cross the shack.
Ill
Vasarajs was sentenced to pay a $25 special assessment pursuant to 18 U.S.C. § 3013. The Supreme Court recently reversed our ruling in
United States v. Mu
*450
noz-Flores,
AFFIRMED.
Notes
. The statute provides, in relevant part, that "[wjhoever reenters or is found within any such *445 [military] reservation ... after having been ... ordered not to reenter by any officer in command or charge thereof — [s]hall be fined not more than $500 or imprisoned not more than six months or both." 18 U.S.C. § 1382.
. The land may contain an easement residing in either the public,
see Watson,
. She would have trouble making such a showing in any event. Nothing in the record indicates that the government granted an express easement to the public when the access road leading to Fort Richardson was first paved.
See The Law of Property, supra
note 2, § 8.3. Moreover, we have no indication that the public made use of this land prior to the time it was acquired by the government such that an easement could be implied,
see id.
§ 8.4; and even if prior use were established, appellant would have a difficult time establishing that use of this land is in any way "necessary,”
see id.
The only use it is “necessary" for is to get to the heart of the Fort, an area from which nobody seriously disputes the government can exclude outsiders: the record fails to disclose that traversing this roadway is essential in order to get to some public place on the other side of the Fort.
Compare Watson,
Finally, even if Vasarajs could prove that the arcane time and use requirements of a prescriptive easement were fulfilled,
see id.
§ 8.7, she would face the traditional bar that “prescriptive rights cannot be obtained against the federal government.”
See United States v. 1,629.6 Acres of Land,
.Indeed, it is a claim she could not make, for adverse possession cannot be achieved against the federal government.
See United States v. Pappas,
. For a discussion of dedications, see The Law of Property, supra note 2, § 11.6.
. Apart from this dictum, appellant’s reliance on the series of cases originating in
Flower v. United States,
. Nor could she assert such a defense. Generally, a criminal defendant’s mistake of fact can only be a valid defense if it negates the existence of a requisite mens rea component of the crime charged and if the crime allows for the interposition of such a defense.
See United States v. Brooks,
We have previously ruled that the first portion of § 1382, proscribing entry "for any purpose prohibited by law,” is not a "specific intent” crime,
United States v. Mowat,
Vasarajs’ mistake about the exact boundary of Fort Richardson cannot negate the requisite mens rea component of § 1382. For appellant admits that she purposely set out to enter the base and only changed her mind at the guard shack when she saw that cars were being searched. Her intent at the actual point of entry (i.e., the approach road between the exit ramp off the highway and the guard shack) exceeded that which was necessary to sustain a conviction. The magistrate found that the "defendant's efforts to leave Fort Richardson on March 14 were directed toward avoiding the random search in the vicinity of the gate. They were not meant to avoid entering the jurisdiction of the base because of the barment order.” The district court affirmed, stating "[i]t is clear that appellant intended to enter the base while traversing the road in question (approach to main gate).” Appellant does not dispute this finding. Thus, even had Vasarajs understood that the actual boundary of Fort Richardson was at the end of the exit ramp, her intent upon reaching the boundary still would have been to enter the Fort. By the time she changed her mind up near the guard shack, she already had fully committed the crime.
. We apparently never ' before have been presented with a defendant convicted of violating § 1382 who claimed she lacked knowledge of a reservation’s boundary lines. In past cases the defendant was arrested either after reentering the same part of the base from which he previously had been expelled,
see Trenouth v. United States,
. In rare situations, when "circumstances which might move one to inquire as to the necessity [of conducting oneself in a particular manner so as to avoid criminal liability] are completely lacking,”
Lambert,
. This analysis treats the letter received by Vasarajs as the functional equivalent of a statute, albeit one written especially for her.
