concurring in part and dissenting in part.
I
The court holds that all extradition treaties to which the United States is a party, including the Mexican-American Extradition Treaty, bar the United States from arresting any suspect within the territory of any other signatory nation. See supra at 1362.
I would rest our holding solely on the ground that Article 9 of the Mexican-American Extradition Treaty bars the United States from arresting a Mexican national like Verdugo within the territory of Mexico. This does not imply that I would disagree with the court’s ruling if I were to reach it, but only that I believe our ruling should be no broader than required for the disposition of the case before us, particularly in a developing area of the law.
Article 9 of the Treaty provides:
Extradition of Nationals
1. Neither Contracting Party shall be bound to deliver up its own nationals, but the executive authority of the requested Party shall, if not prevented by the laws of that Party, have the power to deliver them up if, in its discretion, it be deemed proper to do so.
2. If extradition is not granted pursuant to paragraph 1 of this Article, the requested Party shall submit the case to its competent authorities for the purpose of prosecution, provided that Party has jurisdiction over the offense.
The text of Article 9 plainly reveals the intent of each of the contracting nations to retain absolute discretion to decide whether its own nationals shall be tried in its own courts, or in those of the other contracting nation. The Treaty declares “Neither Contracting Party shall be bound to deliver up its own nationals,” Treaty, Article 9, 111, but imposes on each nation an obligation to prosecute its nationals whom it chooses not to extradite. Treaty, Article 9, II2. As the court states, these requirements “only make[] sense as a blanket reservation of each nation’s sovereign interest in subjecting its own citizens to its own courts, limited only by its own purely discretionary power to deliver such citizens to the other nation.” See supra at 1350.
Other indicia suggest this intent. The Mexican Extradition Law of 1975 prohibits the government of Mexico from extraditing its own nationals. Ley de Extradición In-ternacional, Diario Official de la Federación Mexicana (Dec. 29, 1975). The purpose of the statute is to guarantee Mexican nationals the protections of their own judicial system, shielding them from the uncertainties of exposure to those of other nations. So important is this right to Mexico that since the adoption of its Constitution at the turn of the century it has never entered into any Treaty obligating it to extradite its own nationals. Garcia-Moreno & De La Fuente, La Nueva Ley Mexicana de Ex-tradición Internacional, 1 Revista Mexicana de Justicia 47, 56-57 (Sept.-Oct. 1979).
When the United States entered into the Mexican-American Extradition Treaty, it knew the Treaty was intended to confine prosecution of Mexican citizens to Mexican courts. In submitting the Treaty to the Senate for ratification, Secretary of State Vance wrote “Article 9 ... takes into account the law of Mexico prohibiting the extradition of its nationals but allowing for their prosecution in Mexico.... ” Senate Exec.Rep. No. 21, 96th Cong., 1st Sess. 6 (1979) (Letter of Submittal). Since it is inconceivable that Mexico would enter into a treaty designed in part to protect the right of Mexican nationals to be tried only in their own courts, and yet agree that the United States retained power to kidnap and try Mexican nationals in United States courts without the consent of Mexico, Article 9 must be read as prohibiting the kidnapping of Mexican nationals in Mexico.
If the United States kidnapped Verdugo in violation of Article 9 and Mexico did not acquiesce, the courts of the United States are bound to enforce the Treaty and decline to exercise jurisdiction over the defendant. The Supreme Court made this clear in United States v. Rauscher, 119 U.S. 407, 7 S.Ct. 234, 30 L.Ed. 425 (1886), and Cook v. United States, 288 U.S. 102, 53 S.Ct. 305, *136477 L.Ed. 641 (1933). Neither Ker v. Illinois, 119 U.S. 436, 7 S.Ct. 225, 30 L.Ed. 421 (1886), nor Frisbie v. Collins, 342 U.S. 519, 72 S.Ct. 509, 96 L.Ed. 541 (1952), is to the contrary.
As the court states in Part III(D), the Supreme Court has recognized from the day Ker was decided that courts will enforce treaty provisions that limit the methods the United States may use to obtain custody of a criminal suspect. In United States v. Rauscher, 119 U.S. 407, 7 S.Ct. 234, 30 L.Ed. 425 (1886), a companion case to Ker, the Court held that when the United States obtains custody over a defendant through the formal extradition process, it may not try the defendant for crimes other than the crime of extradition. Id. at 419-23, 7 S.Ct. at 240-42. The Court explicitly rejected the government’s argument “that once being within the jurisdiction of [the United States], no matter by what contrivance or fraud[,] or by what pretence of establishing a charge provided for by the extradition treaty he may have been brought within the jurisdiction, he is, when here, liable to be tried for any offence against the laws as though arrested here originally.” Id. at 422, 7 S.Ct. at 242; see also Johnson v. Browne, 205 U.S. 309, 27 S.Ct. 539, 51 L.Ed. 816 (1907) (applying Rauscher).
In Cook v. United States, 288 U.S. 102, 53 S.Ct. 305, 77 L.Ed. 641 (1933), American officials boarded and seized a British vessel, Mazel Tov, and assessed a substantial fine against its master, Frank Cook. Id. at 107-08, 53 S.Ct. at 306-07. Cook argued the seizure violated a treaty between the United States and Great Britain regulating the boarding by United States officials of British vessels located in international waters. Id. at 109-11, 53 S.Ct. at 307-08. The Court agreed and held that because the seizure violated the treaty the United States was without jurisdiction to libel the vessel. Id. at 120-22, 53 S.Ct. at 311-12. As the Court said, “[t]o hold that adjudication may follow a wrongful seizure would go far to nullify the purpose and effect of the Treaty.” Id. at 121-22, 53 S.Ct. at 312.
Together, Rauscher and Cook stand for the unsurprising proposition that the government of the United States may enter into a treaty regulating American extraterritorial law enforcement activities, and American courts are bound to enforce such a treaty as “the supreme Law of the Land.” U.S. Const. art. VI, cl. 2.
Ker and Frisbie cannot reasonably be read to suggest otherwise. The Court in Ker held as a matter of treaty interpretation that the particular Peruvian treaty did not provide fugitives fleeing from justice in the United States with a guarantee of asylum if they safely reached Peru. Ker, 119 U.S. at 442, 7 S.Ct. at 228. As the Court has since observed, Ker involved no treaty violation; if the United States violates a treaty “the question is quite different.” Ford v. United States, 273 U.S. 593, 606, 47 S.Ct. 531, 535, 71 L.Ed. 793 (1927). Since Article 9 of the Mexican-American Treaty clearly bars the United States from kidnapping a Mexican national like Verdugo in Mexico for trial in United States courts, the Ker holding is inapposite. Frisbie, as this court observes, also has no relevance to this case. It deals strictly with a claim that an interstate kidnapping violated the Due Process Clause and the Federal Kidnapping Act. See supra at 1347 (citing Frisbie, 342 U.S. at 520, 72 S.Ct. at 510).
In sum, Article 9 of the Mexican-American Extradition Treaty in itself barred the alleged abduction of Verdugo from Mexico.
II
Although I agree with the court that the United States violated the Treaty if it kidnapped Verdugo, I cannot agree we may now decide either as a matter of law or of fact that Verdugo has a derivative right to rely upon that violation to bar his trial and conviction in a United States court. In my opinion that issue should be remanded to the district court for initial consideration.
As the majority recognizes, the rights at stake are Mexico’s rights; any right Verdugo may have is entirely. derivative. See supra at 1346-1347. The rights under the Treaty may be waived by Mexico over the defendant’s objection, see supra at 1352; *1365United States v. Valot, 625 F.2d 308, 310 (9th Cir.1980), and Mexico’s silence after a treaty violation will be construed as a waiver of its rights. See supra at 1352; Matta-Ballesteros v. Henman, 896 F.2d 255, 259-60 (7th Cir.1990); United States v. Zabaneh, 837 F.2d 1249, 1261 (5th Cir.1988); United States ex. rel. Lujan v. Gengler, 510 F.2d 62, 67-68 (2d Cir.1975). Verdugo’s standing to seek repatriation because of the alleged treaty violation thus depends upon an assertion of that right by Mexico.
The court concludes that because Mexico protested the alleged kidnapping of Verdu-go as a violation of the Treaty, Mexico necessarily, and as a matter of law, objected to Verdugo’s trial and sought his return, thus preserving Verdugo’s derivative standing to assert that right. Alternatively, the court finds that in fact Mexico did object to Verdugo’s trial and did seek his return. Both of the court’s rulings are premature and, in my opinion, ill advised.
The legal question the court decides and the factual issue it resolves were not squarely addressed by the district court. The district court rested its decision solely on the ground that a kidnapping by the United States would not violate the Mexican-American Extradition Treaty. The court did not address the legal question of whether Mexico’s protest that the Treaty had been violated by Verdugo’s alleged kidnapping was alone enough to give Verdugo standing to demand repatriation, nor did it decide whether Mexico had in fact demanded Verdugo’s return.
Neither the legal nor the factual issue was briefed in this court until we ordered supplemental briefs. The briefs the parties than filed did not discuss the legal issue adequately or the factual issue at all.
We have discretion to remand a question of law to the district court when, as here, it has not been addressed by the district court, has not been properly briefed by the parties, and involves a question of first impression, see Badea v. Cox, 931 F.2d 573, 575 n. 2 (9th Cir.1991); and we should do so in this instance. Factual issues, of course, are within the exclusive province of the district court and should be left to that court.
If these issues were easily resolved it might be permissible for this court to resolve them in the interest of judicial economy, but this is not the case.
The materials before us strongly suggest the court is mistaken in concluding a diplomatic protest necessarily and as a matter of law implies a reservation of all of a nation’s treaty rights and a blanket objection to all criminal proceedings against the defendant. As the most recent Restatement of the foreign relations law of the United States explains:
If a state’s law enforcement officials exercise their functions in the territory of another state without the latter’s consent, that state is entitled to protest and, in appropriate cases, to receive reparation from the offending state. If the unauthorized action includes abduction of the person, the state from which the person was abducted may demand return of the person, and international law requires that he be returned. If the state from which the person was abducted does not demand his return, under the prevailing view the abducting state may proceed to prosecute him under its laws.
Restatement (3d) The Foreign Relations Law of the United States § 432 comment c (1987) (emphasis added).1
Thus, it would appear that under international practice a nation’s protest that its treaty rights have been violated by the manner in which custody of a criminal defendant was obtained does not in itself constitute an objection to the defendant’s trial or a demand for his return.
*1366A review of the authorities confirms the Restatement view. In most cases, the offended nation does seek “the release or restoration of the person illegally carried away[ ],” and that relief is granted by the offending state. J.B. Moore, 1 A Treatise on Extradition and Interstate Rendition § 194 at 288 (1891).2 However, nations do not always insist upon the dismissal of charges and repatriation of an abducted defendant. When this remedy is not requested it is not awarded. See id. § 193 at 287.
Thus, in the celebrated Eichmann case, Argentina initially insisted upon Eichmann’s repatriation, but later determined not to do so in return for a concession by Israel that Argentina’s sovereign rights had been violated by Eichmann’s abduction. Because Argentina chose not to demand Eichmann’s return, the Israeli court held Eichmann’s kidnapping did not bar the exercise of jurisdiction over Eichmann. See Attorney General v. Eichmann (Dist.Ct.Israel 1961) reprinted in 36 Intl.L.Rep. 18, 63 (1968), aff'd sub nom. Eichmann v. Attorney General (Supreme Ct.Israel 1962) reprinted in 36 Intl.L.Rep. 277 (1968). Similarly, in the Nogales case, when Mexican soldiers “rescued” a Mexican prisoner from an American prison, the United States accepted Mexico’s offer to punish the escaped prisoner and the kidnappers, rather than insisting upon the return of the prisoner. J.B. Moore, 1 A Treatise on Extradition and Interstate Rendition § 196 at 288-90. Again, when a Texas sheriff arranged the kidnapping of a fugitive in Mexico near Tombstone, Arizona, the Mexican government did not insist upon return of the fugitive, but demanded that the kidnappers be punished; the United States promised to do so. Id. § 193 at 287. An apology is all that was required by the United States following the kidnapping of an American from Michigan by Canadian authorities. See J.B. Moore, IV A Digest of International Law § 603 at 329 (1906).
The most recent reported decision is that of the Supreme Court of Germany in # 19 GGART 25 Verfahrenshindernis wegen Verletzung von Hoheitsrechten reprinted in 1985 Neue Zeitschrift fur Strafrecht STZ 464. In this case, the defendant was arrested in the Netherlands by a German police officer and taken back to Germany to stand trial for theft. The Netherlands protested the abduction, but did not request the defendant’s return. The German Supreme Court rejected the defendant’s argument that his abduction divested the trial court of jurisdiction because it violated the Dutch-German extradition treaty and customary international law. The court held:
There is no procedural obstacle [to trial] because of the manner in which the police arrested the accused. The violation of Dutch sovereign rights needs to be considered, according to Article 25 of the German Constitution [incorporating international law as part of German law], only if the Netherlands claims that its sovereignty has been violated and its claims oppose continuance of the criminal prosecution, and the Netherlands has demanded, without undue delay, repatriation of the accused.... No request was made by the Netherlands authorities although they had knowledge of the circumstances in which the accused was arrested. In a note from the Dutch Embassy dated December 20, 1983, no request was mentioned. According to that note, the “Dutch government considered *1367this incident a serious offense to Dutch sovereignty” and “requests the Foreign Department for an immediate reply” but [the note] did not include a repatriation demand.3
Because the issue was not explored in the district court and this court has not been aided by adequate briefing, we cannot be confident we are fully aware of the significance of a diplomatic protest that an abduction has violated a treaty. From the material cited, however, it appears possible if not probable that this court’s holding that as a matter of law such a protest is equivalent to an assertion of the right under the treaty to terminate a criminal prosecution and repatriate the defendant, is contrary to prevailing diplomatic understanding and hence to the expectations of the protesting nation. As the United States has argued to this court, nations often lodge a formal protest only to vindicate their national dignity or satisfy domestic political concerns. Under the court’s approach, a nation may not elect this option without also aborting the criminal proceeding in the offending nation and requiring return of an individual the offended nation may not wish (or may be unable) to bring to trial in its own courts.4
In addition to holding a protest alone is sufficient to trigger all of Mexico’s potential rights under the Treaty, the court finds as a fact that Mexico intended to exercise its right to halt Verdugo’s trial and require his return. The court rests this finding upon the subsidiary fact that Mexico asked the Department of State to inform the “U.S. judicial authorities” that Mexico had protested Verdugo’s abduction as a violation of the Treaty. See supra at 1360.
Even if it were appropriate for an appellate court to resolve this factual issue, the record available to us is not adequate to permit us to do so. All we have before us is the text of two notes sent by Mexico to our State Department. We do not know the circumstances in which the notes were presented nor what other communication may have occurred between the two governments.
Moreover, the scanty record before us strongly indicates Mexico did not intend by its protest to seek Verdugo’s return to Mexico for trial. This appears most clearly from a comparison of Mexico’s protest in this case with its protest in a companion case involving Doctor Alvarez-Machain. See United States v. Caro-Quintero, 745 F.Supp. 599 (C.D.Cal.1990) (pending on appeal in this court sub nom. United States v. Alvarez-Machain, No. 90-50459).
After an evidentiary hearing, the district court in Caro-Quintero found the United States had hired Mexican citizens to abduct Dr. Alvarez-Machain and bring him to the United States for trial for his alleged role in the murder of Agent Camarena. Id. at 603.
Mexico’s reaction was prompt and unambiguous. The abduction occurred on April 2,1990. On April 18,1990, Mexico requested our State Department to provide an official report on the role of the United States in the abduction. Id. Following the United States’ response,5 Mexico submitted a protest to the State Department dated May 16, 1990: The note stated:
The Government of Mexico considers that the kidnapping of Dr. Alvarez Ma-*1368chain and his transfer from Mexican territory to the United States of America were carried out with the knowledge of persons working for the U.S. Government, in violation of the procedure established in the extradition treaty in force between the two countries.
The note concluded:
Consequently, the Embassy of Mexico, on the specific instructions of its Government, requests that the Department of State intercede with the appropriate authorities so that Dr. Alvarez Machain can be returned and investigated regarding possible participation in offenses, the investigation and prosecution of which are the responsibility of the Mexican Government. The Embassy therefore respectfully urges the U.S. Government to offer its cooperation so that the aforementioned individual can be tried and sentenced with absolute respect for Mexican laws for any offenses in which he may have been involved.6
Mexico’s note of protest left no doubt Mexico sought the return of Dr. Alvarez-Ma-chain for investigation and trial in Mexico in conformity with Article 9 of the Treaty. Moreover, on November 9, 1990, Mexico’s Consul General in Los Angeles submitted a letter to this court reiterating Mexico’s position that the Mexican-American Extradition Treaty required that Alvarez-Maehain be returned to Mexico and urging this court to uphold the district court’s ruling to that effect.
The contrast with Mexico’s communications in the present case is striking, and may well be significant. In this case Mexico’s first diplomatic note was dated three months after Verdugo’s apprehension. It referred to newspaper reports that Verdu-go had been abducted by Mexican police officers hired by the United States, and requested information regarding the incident. The United States responded that the apprehension of Verdugo was accomplished pursuant to a long-standing local practice of cooperation between law enforcement agents of the United States and Mexico, and that the Mexican police were not hired by United States authorities. After a silence of six months Mexico sent a second communication, noting that Judge J. Lawrence Irving, then presiding over Ver-dugo’s trial on narcotics charges, had recently made a factual finding that the United States had hired Mexican police officers to kidnap Verdugo, contrary to the earlier representations of the United States. Mexico also noted Judge Irving found no treaty violation had occurred because Mexico had not protested Verdugo’s abduction. Mexico requested “the kind mediation of the Department of State in informing the corresponding U.S. judicial authorities of the position of the Mexican Government so that this case will be properly clarified.”
Mexico did not request Verdugo’s return; it did not say it intended to investigate and try Verdugo pursuant to Article 9 of the Treaty. It asked only that the district court trying Verdugo on narcotics charges be advised that Mexico had objected to his abduction.
The United States responded by pointing out Mexico had misconstrued Judge Irving’s findings — and that Judge Irving actually found, consistent with the United States’ earlier representations to Mexico, that the United States had not paid the Mexican officers to kidnap Verdugo. The Department of State also advised Mexico that in accordance with Mexico’s request district court had been informed that Mexico had protested the kidnapping. The note closed with assurances that the United States respected the territorial sovereignty of Mexico and that it had acted in good faith in the reasonable belief that delivery of Verdugo to the United States by Mexican officers reflected a law enforcement decision of the appropriate Mexican authorities. The note concluded: “The Depart*1369ment trusts that the foregoing clarifies any misunderstandings regarding this case, and looks forward to continued cooperation between the two governments on law enforcement matters.” Following these assurances by the United States, the Director General of the Mexican Federal Judicial Police authorized a joint Mexican-American search of Verdugo’s homes in Mexicali and San Felipe, Mexico. United States v. Verdugo-Urquidez, 494 U.S. 259, 110 S.Ct. 1056, 1059, 108 L.Ed.2d 222 (1990).
It may also be significant that Mexico’s note of protest was lodged while Verdugo was facing trial on narcotics charges before Judge Irving in the Southern District of California, well over a year before this prosecution for murder began. So far as the record before us indicates, Mexico did not object to this proceeding against Ver-dugo for murder: Mexico remained silent when Verdugo was indicted on the present charges, remained silent when Verdugo went to trial, remained silent when Verdu-go received an unfavorable ruling below on the treaty issue, and remained silent when Verdugo was convicted.
On the basis of this information, and such other evidence a properly developed record might contain, a trier of fact might agree with this court’s finding that Mexico intended that this criminal proceeding be abated and Verdugo be returned to Mexico. However, a trier of fact could also conclude that Mexico intended only to protest a possible invasion of its territorial integrity and treaty rights; that it was satisfied with the explanation given by the United States and with the formal assurances by the United States that the United States respected Mexico’s rights as a sovereign and as a party to the Treaty; and that Mexico was satisfied to allow Verdugo’s trial and conviction to stand. The trial court should be allowed to decide which inference to draw.
For these reasons, I dissent.
. Contrary to the majority’s suggestion, see supra at note 22, Reporters’ Note 3 of the Restatement is entirely consistent with the Restatement text. Reporters’ Note 3 unambiguously states:
Under the prevailing practice ... states ordinarily refrain from trying persons illegally brought from another state only if that state demands his return.
Restatement (3d) The Foreign Relations Law o/ the United States § 432 Reporters' Note 3.
. For example, in the Bratton case over a century ago, a Canadian national was kidnapped in Canada by Americans and brought to South Carolina for trial. The British government demanded that the charges be dismissed and Bratton be permitted to return to Canada. The United States complied. J.B. Moore, 1 A Treatise on Extradition and Interstate Rendition § 190 at 283-84. Similarly, in the Blair case, the United States insisted upon the return of an American citizen kidnaped by Great Britain and the British government complied. Id. § 191 at 285. More recently, in United States v. Caro-Quintero, 745 F.Supp. 599 (C.D.Cal.1990), the government of Mexico demanded the return of the defendant following his kidnapping by paid agents of the United States, id. at 603-04, 608, and the district court ordered his return. Id. at 614. Caro-Quintero is currently on appeal before another panel of this court sub nom. United States v. Alvarez-Machain, No. 90-50459.
.Contrary to the majority’s suggestion, see supra at note 22, the German court's conclusion that a repatriation request is required was not dictum. As the quoted text reveals, the lack of a repatriation request was essential to the court’s holding. Nor was the German court’s decision based upon the peculiarities of German constitutional law. Article 25 of the German constitution, relied upon by the German court, merely incorporates international law as part of German law. Thus, the German court’s decision rests squarely upon the customary practice among nations.
. The majority defends its bright line rule by suggesting that an inquiry into the actual intent of Mexico “comes dangerously close to the inquiries forbidden under the political question doctrine.” Supra at note 22. The majority fails to explain why presuming, contrary to diplomatic practice, that Mexico’s protest was intended as a demand for Verdugo’s repatriation, is any less invasive of the executive sphere than determining whether in fact Mexico has demanded Verdugo’s return.
. This court does not have a copy of the United States' response.
. Mexico’s letter of protest was not part of the record below. However, a diplomatic protest is a public document of which we may take judicial notice. See, e.g,, United States v. Payton, 918 F.2d 54, 56 (8th Cir.1990); United States v. Jordan, 913 F.2d 1286, 1287 n. 2 (8th Cir.1990); Fibreboard Paper Prod. Corp. v. East Bay Union of Machinists, Local 1304, 344 F.2d 300, 302 n. 2 (9th Cir.1965); Zahn v. Transamerica Corp., 162 F.2d 36, 48 n. 20 (3d Cir.1947); National Labor Relations Board v. E.C. Atkins & Co., 147 F.2d 730, 734 n. 1 (7th Cir.1945).