191 F.3d 976 (9th Cir. 1999)
UNITED STATES OF AMERICA, Plaintiff-Appellee,v.RODNEY PHILLIP TIDWELL, Defendant-Appellant.
No. 98-10164
UNITED STATES COURT OF APPEALS FOR THE NINTH CIRCUIT
Argued and Submitted May 11, 1999Filed August 20, 1999

[Copyrighted Material Omitted]
Jess A. Lorona, Burch & Cracchiolo, Phoenix, Arizona, for  the defendant-appellant.
Paul Charlton and Diane Humetewa, Assistant United States Attorneys, Phoenix, Arizona, for the plaintiff-appellee.
Appeal from the United States District Court for the District of Arizona; Earl H. Carroll, District Judge, Presiding.  D.C. No. CR-97-00093-02-EHC.
Before: Herbert Y. C. Choy, Paul R.  Michel,1 and Sidney R. Thomas, Circuit Judges.
THOMAS, Circuit Judge:


1
Rodney Tidwell appeals his jury conviction and sentence,  primarily contending that the Native American Graves Protection and Repatriation Act ("NAGPRA") is unconstitutionally  vague. We affirm the conviction and the sentence imposed by  the district court.


2
* Defendant-appellant Rodney Tidwell and Ernest Chapella  were indicted on twelve counts of illegal trafficking in Native  American cultural items, eleven counts of theft of tribal property, one count oftrafficking in unlawfully removed archaeological resources, one count of interstate transportation of  stolen property, and conspiracy to commit illegal trafficking  of Native American cultural items and theft of tribal property.  Soon thereafter, Chapella committed suicide.


3
The government's indictment arose out of an undercover  investigation of Tidwell after it received a tip from a confidential informer that Tidwell was trafficking in stolen or protected Native American cultural items. Agent John Fryar, an  investigator with the Bureau of Indian Affairs, conducted the investigation and presented himself to Tidwell as a purchaser  of Native American art. In a series of meetings with Tidwell,  Fryar purchased and attempted to purchase a number of items  that the government later learned were religious, cultural, or  historical items belonging to two different Native American  groups. These items included eleven Hopi masks, also called  Kwaatsi or Kachina, and a set of priest robes from the Pueblo of Acoma.


4
During his final meeting with Tidwell, Fryar discussed the  purchase of three other masks. While Tidwell and Fryar discussed this purchase, federal agents executed a search warrant  on Tidwell at his home. In addition to the three masks that  Fryar was in the process of purchasing, the agents found two  more masks at Tidwell's house.


5
At trial, the government introduced the taped conversations  between Agent Fryar and Tidwell. The government also introduced a number of experts on Native American religion and  culture who testified that the masks and the robes were prohibited from being sold under the NAGPRA. In his defense,  Tidwell introduced testimony of Native Americans who testified that the masks were not authentic Hopi masks and also  that the masks Tidwell purchased and sold were not the type  of cultural item protected by the NAGPRA.


6
After the trial, the jury convicted Tidwell of conspiracy  under 18 U.S.C. S 371, seven counts of illegal trafficking in  Native American cultural items under 18 U.S.C. S 1170,  eleven counts of theft of tribal property under 18 U.S.C.  S 1163, and one count of trafficking in unlawfully removed  archaeological resources under 16 U.S.C. S 470ee. The masks and the robes formed the basis of the convictions under the  NAGPRA, the masks alone formed the basis for the convictions for theft of tribal property and the conspiracy conviction,  and the robes alone formed the basis for the conviction for  trafficking in unlawfully removed archaeological resources.


7
The district court then added a two-level adjustment to  Tidwell's base offense level for obstruction of justice and a  six-level increase based on the amount of the loss and sentenced Tidwell to thirty-three months in prison.


8
Previous to these convictions, Tidwell had been arrested  and convicted under the NAGPRA.

II

9
We review Tidwell's challenge that the NAGPRA is  unconstitutionally vague de novo, see United States v. Lee,  183 F.3d 1029, 1031-32 (9th Cir. July 9, 1999),  and hold that the NAGPRA is not unconstitutionally vague as  applied to Tidwell. In evaluating vagueness, we consider  whether the challenged law: (1) sufficiently defines the  offense so that ordinary people can understand the prohibited  conduct; and (2) establishes standards to ensure that law  enforcement officers enforce the law in a nonarbitrary and  nondiscriminatory manner. See id.; Nunez v. City of San  Diego, 114 F.3d 935, 940 (9th Cir. 1997). However, "[a]  plaintiff who engages in some conduct that is clearly proscribed cannot complain of the vagueness of the law as  applied to the conduct of others." Village of Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U.S. 489, 495 (1982).


10
The section of the NAGPRA under which Tidwell was convicted states: Whoever knowingly sells, purchases, uses for profit,  or transports for sale or profit any Native American  cultural items obtained in violation of the Native  American Grave Protection and Repatriation Act


11
shall be fined in accordance with this title, imprisoned not more than one year, or both, and in the case  of a second or subsequent violation, be fined in  accordance with this title, imprisoned not more than  5 years, or both.


12
18 U.S.C. S 1170(b). Cultural items are defined in the NAGPRA and include, inter alia, "cultural patrimony." 25 U.S.C.  S 3001(3)(D). Cultural patrimony is:


13
[A]n object having ongoing historical, traditional, or  cultural importance central to the Native American  group or culture itself, rather than property owned by  an individual Native American, and which, therefore, cannot be alienated, appropriated, or conveyed  by any individual regardless of whether or not the  individual is a member of the Indian tribe or Native  Hawaiian organization and such object shall have  been considered inalienable by such Native American group at the time the object was separated from  such group.


14
Id. Tidwell specifically challenges as vague the two elements of cultural patrimony: the "inalienability" of an item, and an  item's "ongoing historical, traditional, or cultural importance"  to a Native American group. He argues that because these  terms are defined by Native Americans and because tribal law  regarding cultural patrimony is not written, it was impossible  for him to have fair notice of his wrongful conduct as proscribed by the NAGPRA. Further, Tidwell points to the testimony introduced at his own trial to demonstrate the  uncertainty in the law: The government introduced expert witnesses who stated that the masks and the robes were cultural  patrimony; he introduced expert witnesses who testified that  the masks were not authentic.


15
In holding that the NAGPRA is constitutional, we adopt  the reasoning of the Tenth Circuit in United States v. Corrow, 119 F.3d 796 (10th Cir. 1997), cert. denied, 118 S. Ct. 1089  (1998). Like Corrow, Tidwell is and claims to be a dealer in  Native American art. Therefore, he had the background  knowledge sufficient to put him on notice that some of the  items he traded might be inalienable objects belonging to a  Native American group. Even if he was not sure about  whether a particular item was protected, he had sufficient  understanding of Native American art and the NAGPRA to  know that he would have to inquire further or consult an  expert when he purchased the items. As we repeated in United  States v. Bohonus, "one who deliberately goes perilously  close to an area of proscribed conduct shall take the risk that  he may cross the line." 628 F.2d 1167, 1174 (9th Cir. 1980)  (citations and internal quotation marks omitted). Similar to  the facts presented in Corrow, "this is not a case in which an  unsuspecting tourist . . . innocently purchase[d]" an item pro- tected by the NAGPRA. Id. at 803. Tidwell already had been  convicted under the NAGPRA and was aware of its statutory  prohibition.


16
We also note that the NAGPRA requires the government to establish that the defendant "knowingly " traded in  cultural items in violation of the NAGPRA. This scienter element protects the unwary from criminal punishment. See  Village of Hoffman, 455 U.S. at 499; United States v. Cooper,  173 F.3d 1192, 1202 (9th Cir. 1999); United States v. Lee,  937 F.2d 1388, 1394-95 (9th Cir. 1991).


17
Finally, as determined by the Corrow court, the NAGPRA does not foster arbitrary enforcement because law  enforcement officials must consult with Native American  officials to identify items that are cultural patrimony before  they can investigate and arrest a suspect. See 119 F.3d at 804.  For these reasons, we hold that the Act is not unconstitutionally vague as applied to Tidwell.

III

18
Tidwell's argument that he was improperly precluded  from presenting evidencein his defense fails. Tidwell sought  to introduce evidence that he had constructed one or more of  the masks identified by the government's experts as authentic  Hopi masks. Tidwell's strategy was that, because the NAGPRA only protects items with historical, traditional, or cultural significance to Native Americans, he might avoid  criminal liability by persuading the jury that he had con- structed the masks himself. However, the asthenic evidence  Tidwell sought to introduce would not have proven that  Tidwell had made the masks that he was charged with selling  at trial. Rather, the tendered witnesses only could testify generally that Tidwell had some of the materials with which to  make masks and that some unidentified masks appeared to be  under construction in Tidwell's house. Thus, any error the  district court committed in excluding the evidence was harmless beyond a reasonable doubt. See United States v. Vargas,  933 F.2d 701, 705-06 (9th Cir. 1991).

IV

19
Tidwell argues that the government did not provide sufficient evidence from which a rational jury could have convicted him under the charged statutes. We review the  evidence presented at trial in a light most favorable to the  prosecution to determine if the evidence was sufficient from  which a rational jury could have found the essential elements  of the charged crime beyond a reasonable doubt. See United  States v. Castro, 972 F.2d 1107, 1110 (9th Cir. 1992).


20
There was sufficient evidence from which a jury could  have convicted Tidwell of engaging in a conspiracy with Chapella. To satisfy a conspiracy charge, the government must  present sufficient evidence to demonstrate: (1) an overt act,  and (2) an agreement to engage in criminal activity. See  United States v. Garcia, 151 F.3d 1243, 1245 (9th Cir. 1998).  An implicit agreement may be inferred from circumstantial  evidence if "the nature of the acts would logically require coordination and planning." Id. Here, Agent Fryar testified  that: (1) Tidwell told him he had received the masks from an  Ernest Chapella up on the Hopi Reservation, and (2) Chapella  identified the masks sold by Tidwell to Fryar. In addition,  Witness Clifton Ami connected Chapella to improperly  acquired Hopi masks.


21
The government also presented sufficient evidence to  convict Tidwell for violating the NAGPRA. Under the criminal component of the NAGPRA, 18 U.S.C. S 1170(b), the  government had to prove that Tidwell: (1) knowingly, (2)  sold, purchased, used for profit, or transported for sale or  profit, (3) Native American cultural items obtained in violation of the NAGPRA. See 18 U.S.C. S 1170(b). The government produced expert witnesses who testified that the masks  Tidwell purchased and sold belonged to the Hopi Indians and  were "cultural patrimony." From Agent Fryar's testimony, the  jury reasonably could deduce that Tidwell knew he was selling proscribed tribal artifacts. The government also introduced witnesses who testified that although they had sold the  Acoma robes to Tidwell, they had told Tidwell that they were  prohibited from selling them. A rational jury could have  believed the government's witnesses; therefore, sufficient evidence existed to support the conviction under the NAGPRA.


22
Tidwell also challenges his convictions under 18 U.S.C.  S 1163. Under S 1163, the government must show that  Tidwell: (1) stole or knowingly converted for his use or the  use of another, (2) any property belonging to any tribal organization. See 18 U.S.C. S 1163. The government's evidence  that Tidwell knew that the Hopi owned the masks and were  not permitted to sell them was sufficient to sustain the verdict.


23
Last, Tidwell challenges his conviction under 16 U.S.C.  S 470ee for lack of sufficient evidence. To convict Tidwell for  a violation of this statute, the government had to prove that  Tidwell: (1) purchased or sold, (2) an archeological resource,(3) that was removed from Indian lands, (4) without a permit.  See 16 U.S.C. S 470ee(b). The government's expert archeological testimony and evidence that the robes were owned by  the Pueblo of Acoma were sufficient to permit a rational jury  to conclude that Tidwell violated S 470ee(b) by purchasing  and selling the robes.

V

24
The district court did not err in enhancing Tidwell's  sentence by six levels based on the amount of the loss. The  value of loss is a factual issue. See United States v. Lopez, 64  F.3d 1425, 1427 (9th Cir. 1995). Under the United States Sentencing Guidelines, a district court must first look to market  value when determining the value of the loss of stolen goods.  See United States v. Choi, 101 F.3d 92, 93 (9th Cir. 1996),  cert. denied, 520 U.S. 1120 (1997). " `Ordinarily, when property is taken or destroyed the loss is the fair market value of  the particular property at issue.' " Id.  (quoting U.S.S.G.  S 2B1.1 application note 2). In cases in which market value  " `is difficult to ascertain or inadequate to measure harm to  the victim, the court may measure loss in some other way,  such as reasonable replacement cost to the victim.' " Id. In  United States v. Pemberton, we affirmed a district court's valuation of stolen technical drawings based on their contract price because the drawings were unique and without a "broad  and active market." See 904 F.2d 515, 517 (9th Cir. 1990).


25
In this case, the district court valued the masks at the  prices Tidwell asked Fryar to pay for them. Because the items  do not have a broad and active market, the district court's  decision to use Tidwell's "asking price" was not clearly erroneous.


26
Tidwell also challenges the district court's finding that  Tidwell obstructed justice. We review a district court's determination of obstruction of justice for clear error, but review  de novo whether a defendant's conduct constitutes an obstruction of justice. See United States v. Morales , 977 F.2d 1330,  1330-31 (9th Cir. 1992). Findings of fact related to a defendant's attempt to obstruct justice must be supported by a preponderance of the evidence, see United States v. Garcia, 135  F.3d 667, 670 (9th Cir. 1998), but a sentencing judge may  consider hearsay testimony or other evidence that would not  otherwise be admissible at trial, see United States v. Sustaita,  1 F.3d 950, 952 (9th Cir. 1993).


27
The district court did not err in determining that Tidwell  obstructed justice. The court found by a preponderance of the  evidence that Tidwell willfully created affidavits with the  expectation that they would mislead the court. Further, there  was evidence, although controverted, that Tidwell attempted  to improperly influence a witness by offering cash and that  Tidwell intimidated a witness. Therefore, the district court  could have determined that a preponderance of the evidence  supported the adjustment. See U.S.S.G. S 3C1.1 & application  note 4.

VI

28
In sum, we reject Tidwell's vagueness challenge to the  NAGPRA and affirm his convictions as supported by sufficient evidence. Any error the district court made in excluding  testimony was harmless. The district court did not err in its  sentencing adjustments.


29
AFFIRMED.



Note:


1
 The Honorable Paul R. Michel, United States Circuit Judge for the Federal Circuit, sitting by designation.


