The court voted 8-1 Wednesday in favor of Lamar Evans, who was charged with arson after he was seen running away from a burning vacant house in Detroit with a gasoline can in his hand.
A judge acquitted Evans midway through his trial based on a mistaken interpretation of the law.
Justice Sonia Sotomayor said for the court that the acquittal is final, even if granted in error. Justice Samuel Alito dissented.
The case is Evans v. Michigan, 11-1327.