… to a jury beyond a reasonable doubt.

Here are the materials in United States v. Zepeda:

CA9 opinion

CA9 memorandum (related opinion on other issues)

Zepeda Opening Brief

US Answer Brief

Zepeda Reply Brief

US Supplemental Brief

Zepeda Supplemental Brief

The court’s summary:

The panel reversed jury convictions under the Major Crimes Act, 18 U.S.C. § 1153, which provides for federal jurisdiction over certain crimes committed by Indians in Indian country.
The panel held that whether a given tribe is federally recognized, as required for jurisdiction under § 1153, is a question of fact for the jury, not a question of law for the court; and rejected the government’s request that this court take judicial notice of the Bureau of Indian Affairs’s list of federally recognized tribes in 2008 and 2010.
The panel held that a Certificate of Enrollment in an Indian tribe, entered into evidence through the parties’ stipulation, is insufficient evidence for a rational juror to find beyond a reasonable doubt that a defendant is an Indian for purposes of § 1153, where the government offers no evidence that the defendant’s bloodline is derived from a federally recognized tribe.
Dissenting, Judge Watford would hold that federal recognition of an Indian tribe is a question of law for the court to resolve.