The Gamble appeal followed soon after, with the briefs by both parties and amici curiae suggesting that many think the Court is ready to scrap the “separate sovereigns” theory. Those briefs dwell largely on theoretical issues such as the “original public meaning” of the Fifth Amendment and the “core principles of federalism.” Very little is said about whether a new rule would further the concrete aims of criminal justice, or how many cases a change would affect.

According to a view popular with judges, the federal-state relationship is a brilliant invention of wise Founders who wished to make it harder for government to impede “liberty.” Obstacles to prosecution, some believe, are features of the system. Others, including groups who seek the protection of the federal sovereign from abuse or neglect by local sovereigns, see those obstacles as bugs.

Read: Testing territorial limits

In its brief, the Thurgood Marshall Civil Rights Center at Howard University School of Law reminds the Court that a change in the “separate sovereigns” rule, if not carefully managed, might end up making federal civil-rights statutes difficult, or even impossible, to enforce. “Although this case does not concern police misconduct or federal civil rights enforcement, a decision to abolish dual sovereignty inevitably will require reexamination of several interrelated double jeopardy issues that impact on federal criminal civil rights enforcement,” the brief argues. It asks the justices to take care that a decision in Gamble “not adversely affect or otherwise foreshadow any particular outcome when the framework of a civil rights ‘exception’ ultimately arises in future litigation.”

The Howard Law School professor Adam Harris Kurland, who authored the brief, has written a book-length study of double jeopardy and federal-state relations. In an interview, he argued that the issue before the Court is not simply the “intent” or “understanding” of the Framers of the Bill of Rights, but the structure of the post–Civil War Constitution, which envisions a federal role in protecting minority rights. Citing the work of the Yale professor Akhil Reed Amar, Kurland noted that the federal government needs, at a minimum, the power to prosecute state officials, such as police, who use legal authority to violate constitutional rights. Beyond that, hate-crime laws and prohibitions on housing discrimination might be affected by an overbroad opinion that overturns the “separate sovereigns” rule, he said. “I would expect that each member of the Court would not just make the decision in the abstract.” There’s little evidence that the present rule is unworkable, he added; an overbroad ruling might “unravel the complex tapestry of more than 150 years of double-jeopardy jurisprudence and stare decisis.”

The National Indigenous Women’s Resource Center is on the same side. In a brief, its lawyers argue that a wholesale rejection of the “separate sovereigns” rule would roll back a hard-won victory in the fight against domestic violence and sexual abuse in Indian country.