OPINION OF THE COURT
Goldin, Jackson, Gayer, Kissinger and Cohen (Protesters) participated in a protest at the Liberty Bell Pavillion (Pavillion) in Independence National Historic Park on July 3, 1999, one of the busiest days of the year at the park. The protest got out of control and Park Rangers moved in to restore order. Protesters were arrested for refusing to obey the lawful order of a Park Ranger in violation of 36 C.F.R. § 2.32(a)(2). Protesters were found guilty in a proceeding before a United States Magistrate Judge. Each protestor received the same sentence: one year probation with travel restricted to the federal district in which he or she resided, a $250.00 fine, and a $25 assessment.
Protesters appealed their convictions and sentences to the district court and, after affirmance, appealed to this court. The Magistrate Judge had jurisdiction under 18 U.S.C. § 3401(a), the district court had appellate jurisdiction under 18 U.S.C. § 3742(g), and we have jurisdiction over this timely filed appeal under 28 U.S.C. § 1291. We affirm.
I.
Protesters first contend that the evidence was insufficient to prove that they committed the offense charged. We “review[ ] the sufficiency of the evidence in the light most favorable to the government and must credit all available inferences in favor of the government.”
United States v. Riddick,
Protesters’ first insufficiency argument is that they were either not given an order or were not given an opportunity to comply. Kissinger, Goldin, and Cohen were arrested after they blocked a police van. All three were told to move, all three were given between twenty and thirty seconds to move, and all three refused.
Jackson was arrested after she rolled her motorized wheelchair past a police barricade. She was told to leave, refused to do so, and then demanded to be arrested. When viewed in the light most favorable to the government, the evidence was sufficient to show that Kissinger, Goldin, Cohen, and Jackson were given both an order to move and an opportunity to comply.
Gayer does not argue that she was not given an order or opportunity to move. Rather, she argues that the order she was given was not lawful because it was arbitrary. An order given under 36 C.F.R. § 2.32(a)(2) must be “lawful.” For an order to be lawful under the regulation, it must be 1) given in one of the circumstances outlined in section 2.32(a)(2) and 2) constitutional. The order Gayer received was given in a circumstance outlined in section 2.32(a)(2). Because the order was given after Gayer had interrupted a park service presentation and while she was preventing new tourists from accessing the Pavillion, it was given during another “activity] where the control of public movement and activities [was] necessary to maintain order and public safety.” Id. Since the order Gayer received was given in one of the circumstances outlined in *195 section 2.32(a)(2) and, as we conclude later, was constitutional, it was lawful.
Kissinger, Goldin, and Cohen also argue that the evidence at trial was insufficient to show that they were among those that blocked the police van. Viewed in the light most favorable to the government, the evidence — especially the eye-witness testimony — was sufficient to show that Kissinger, Goldin, and Cohen were amongst those that blocked the police van.
Protesters argue further that the evidence was insufficient to support their convictions because it did not show that there was an emergency at the time they were arrested. One of the provisions of 36 C.F.R. § 2.32(a)(2) requires an order to be given during “emergency operations.” Protesters suggest that the emergency had abated by 12:30 or 1:00 p.m. The videotape introduced at trial, though, showed that the Pavillion was blocked at 12:28 p.m. and that the last protesters were not removed from the Pavillion roof until 2:23 p.m. This was sufficient to show that an emergency existed during this period. Cohen, Goldin, and Kissinger were arrested at 1:31 p.m. Although Jackson was never arrested (only cited), she was told to leave the blockaded area and refused at approximately 1:08 p.m. Viewed in the light most favorable to the government, the evidence was sufficient to show that Cohen, Goldin, Kissinger and Jackson disobeyed a Park Ranger’s order during “emergency operations.” We have no need to decide whether Gayer’s arrest occurred during emergency operations because, as we have already discussed, her arrest was authorized by another provision in 36 C.F.R. § 2.32(a)(2).
II.
Protesters next argue that 36 C.F.R. § 2.32(a)(2) is unconstitutional.
A.
Their first argument is that it violates the Due Process Clause of the Fifth Amendment because it is too vague.
[T]he void-for-vagueness doctrine requires that a penal statute define the criminal offense with sufficient definiteness that ordinary people can understand what conduct is prohibited and in a manner that does not encourage arbitrary and discriminatory enforcement.
Kolender v. Lawson,
Protesters assert that the Regulation, unless confined to operations that are the equivalent of “firefighting or wild animal control operations” is so unclear that it “encourages arbitrary and discriminatory enforcement” by the Park Rangers. Id. at 357,
The Court struck down the ordinance because its definition of loitering — “remaining in any one place with no apparent purpose” — was so vague that it gave Chicago police “absolute discretion ... to determine what activities constituted loitering.” Id.
36 C.F.R. § 2.32(a)(2) is unlike the ordinance in Morales because it carefully confines a Park Ranger’s authority to issue an *196 order. For 36 C.F.R. § 2.32(a)(2) to apply, the Ranger’s order must be given
during firefighting operations, search and rescue operations, wildlife management operations involving animals that pose a threat to public safety, law enforcement actions, and emergency operations that involve a threat to public safety or park resources, or other activities where the control of public movement and activities is necessary to maintain order and public safety.
Unlike the Chicago ordinance, where the police were empowered to order almost anyone standing in place anywhere in the city to disperse, a Park Ranger, under the regulation, may only give an order in a limited, rather narrow, set of circumstances. Two of those circumstances are relevant here: 1)' “emergency operations that involve a threat to public safety or park resources” and 2) “other activities where the control of public movement and activities is necessary to maintain order and public safety.” Id.
Unlike the Chicago ordinance’s definition of loitering, 36 C.F.R. § 2.32(a)(2) is not so unclear that it vests unbridled discretion in Park Rangers. An order given under the “emergency operations” provision, for example, must be given not only in “emergency operations,” but in “emergency operations that involve a threat to public safety or park resources.” What is more, an order given under the “public movement” provision may only be given if
“necessary
to maintain order and public safety.”
Id.
Recognizing that “we can never expect mathematical certainty from our language,”
Hill v. Colorado,
B.
Both Gayer and the American Civil Liberties Union as amicus argue that Gayer’s arrest also implicated Gayer’s First Amendment right to speak freely. Whether the government may restrict a person’s ability to speak on its property depends upon whether the property is “public or nonpublic.”
Kreimer v. Bur. of Police for Morristown,
All parties in this case agree that the Pavillion is a limited public forum. A limited public forum is a public forum only to the extent that it has been “intentionally opened [by the government] ... to the public
for expressive activity.” Kreimer,
Our first inquiry is whether the government had opened the Pavillion to expressive activity like Gayer’s. The evidence taken in a light most favorable to the government, demonstrates that the government had opened the Pavillion to the public to see the Liberty Bell, to take part in a short presentation, and then to leave. The government did not intend to open the Pavillion to speeches made by *197 members of the general public. Indeed, the fact that the government had designated areas outside of the Pavillion for public speech suggests that the Pavillion had not been so designated.
Consequently, we will apply the nonpublic forum reasonableness standard to determine whether Gayer’s arrest under 36 C.F.R. § 2.32(a)(2) was constitutional. Under that standard, we ask whether Gayer’s arrest was “reasonable and not an effort to suppress expression merely because public officials oppose the speaker’s view.”
Perry Educ. Ass’n,
III.
Protesters also argue that the district court should not have admitted a 15 minute video tape of the demonstration because it was not properly authenticated. They argue that the tape, since it was an edited version of the complete two-hour tape, should have been authenticated by the editor instead of Officer Murphy, the camera operator. We review a trial court’s decision to admit evidence for an abuse of discretion.
United States v. Sriyuth,
Protesters also argue that the trial judge should have let them question Officer Murphy about his membership in the Philadelphia Fraternal Order of Police (F.O.P.). They wanted to ask Murphy about his membership because they might have shown, given the F.O.P.’s supposed criticism of Jamal supporters in the past, that Murphy recorded the event in a biased way. Since the tape showed scenes of what actually happened during the emergency at the Pavillion, any bias attributable to Murphy because of his membership in the F.O.P. would have been marginally relevant at best. The trial court did not abuse its discretion when it held that the F.O.P. line of questioning was irrelevant.
Pfeiffer v. Marion Ctr. Area Sch. Dist.,
IV.
Protesters also challenge several aspects of their sentences. They first argue that the trial judge should not have limited their travel to the federal district in which they resided.
A court may impose a special condition of probation to the extent that any such condition is reasonably related to factors *198 set forth in [18 U.S.C. § ]3553(a)(l) and (2), and to the extent that such conditions involve only such deprivations of liberty and property as are reasonably necessary to fulfill the purposes of probation. 18 U.S.C. § 3563(b).
United States v. Warren,
Travel restrictions are a standard probation condition. Id. There was no. abuse of discretion in the trial judge’s imposition of the travel restrictions because those restrictions “reflect the seriousness of the offense, ... promote respect for the law, ... and prove [a] just punishment for the offense.” 18 U.S.C. § 3553.
Protesters also argue that they were punished for exercising their right to go to trial because their sentences were more severe than the sentences received by those demonstrators who chose not to go to trial. We agree with the district court that protesters’ punishment reflects both their lack of remorse and their unwillingness to accept responsibility for them illegal acts.
Further, protesters suggest that it was error for the trial judge to sentence them in a “fixed and mechanical” manner.
See United States v. Thompson,
Finally, it appears that each protester was ordered to pay a $25 assessment instead of-the $10 special assessment authorized by 18 U.S.C. § 3013(a)(l)(A)(ii). The government properly conceded error. We vacate the special assessment and remand to the district court with instructions to decrease the assessment to $10 as to each protester. AFFIRMED IN PART, VACATED IN PART, AND REMANDED.
