Double Jeopardy’s dual sovereignty doctrine doesn’t prohibit the same sovereign — here, the federal government – from prosecuting a defendant under both Native American and federal law, the U.S. Supreme Court held June 13 in Denezpi v. United States.
Merle Denezpi was convicted of assault and battery for a sex offense in a “Court of Indian Offenses,” also known as a CFR Court. 
CFR Courts were created by the Department of the Interior in 1882.  Their rules are contained in the Code of Federal Regulations – hence, “CFR” Courts.  CFR Courts adjudicate penal code violations for Native American tribes which have not established their own judicial systems.
The Ute Mountain Ute Tribe has its own penal code, which it enforces in CFR Court.
Denezpi was convicted under the Tribe’s penal code, and sentenced to 140 days imprisonment.
An officer from the federal Bureau of Indian Affairs filed and prosecuted the case in CFR Court.
Six months later, a federal grand jury indicted Denezpi of aggravated sexual abuse in Indian country, an offense covered by the federal Major Crimes Act.  This charge involved the same incident as the prior conviction in CFR Court. 
Denezpi moved to dismiss on Double Jeopardy grounds.  He contended that since federal authorities prosecuted him in both courts, the second prosecution violated Double Jeopardy.  The District Court denied his motion. 
He was convicted and sentenced to 360 months in prison.
The 10th Circuit affirmed.
The Supreme Court affirmed, in a 6-3 opinion.
The Court said the case was a “twist” on the “usual dual-sovereignty scenario.”
Denezpi’s single act violated two laws – those of the Ute Mountain Ute Code and the federal Major Crimes Act, the Court said. 
“The two laws, defined by separate sovereigns, therefore proscribe separate offenses,” the Court said.
The Court rejected Denezpi’s argument that the dual-sovereignty doctrine “requires that the offenses be both enacted and enforced by separate sovereigns.”
The Double Jeopardy Clause “does not prohibit successive prosecutions by the same sovereign,” the Court said.  “It prohibits successive prosecutions ‘for the same offense,’” the Court said. 
“[A]n offense defined by one sovereign is different from an offense defined by another,” the Court said.  “Thus, even if Denezpi is right that the Federal Government prosecuted his tribal offense, the Clause did not bar the Federal Government from prosecuting him under the Major Crimes Act.”
Dissenting opinion questions constitutionality of CFR Courts
Justice Gorsuch dissented, joined by Justices Sotomayor and Kagan.
Gorsuch reiterated his prior opposition to the dual sovereignty doctrine, but “even taking the doctrine on its own terms, it does not tolerate what transpired here,” he said.
He said prior cases applying the dual sovereignty doctrine required that the two prosecuting “entities” have “derived their power to punish from wholly independent [sovereign] sources.”
Gorsuch questioned the constitutionality of CFR Courts, though noted that issue wasn’t raised in the case.
“[O]ne might wonder how an executive agency [the Bureau of Indian Affairs] can claim the exclusive power to define, prosecute, and judge crimes – three distinct functions the Constitution normally reserves for three separate branches,” he said.  “[T]hose questions – long lingering and incredibly still unanswered – remain for another day.”
Gorsuch noted that Denezpi had “agreed” his first conviction was for a “tribal offense.”  
But, disagreeing with this concession, Gorsuch said that “[w]hether the Court of Indian Offenses enforces federal regulatory offenses rather than tribal offenses remains an open question for other litigants to preserve and pursue – and its answer is clear.”