A longstanding rule allowing trials of defendants on the federal and state level for the same conduct just came into the U.S. Supreme Court’s crosshairs, after the justices granted review of the practice June 28.

The case “will address whether a citizen can be prosecuted twice for the same crime, once by the state and again by the feds—even after he has been acquitted!—which seems like an obvious violation of the Double Jeopardy Clause,” the Cato Institute’s Ilya Shapiro told Bloomberg Law. He co-authored an amicus brief supporting defendant Terance Gamble.

Gamble was convicted of firearm possession in federal court....