In the case of California v. Rooney (1986), the U.S Supreme Court addressed whether a state could impose additional penalties on a defendant who had already been sentenced in federal court for the same criminal conduct. The defendant, Michael Rooney, was convicted and sentenced in both federal and state courts for his role in an armed bank robbery. He argued that this constituted double jeopardy - being tried twice for the same crime - which is prohibited by the Fifth Amendment to the Constitution. The Supreme Court ruled against Rooney, upholding his convictions and sentences in both jurisdictions. They reasoned that because states are separate sovereign entities from the federal government, each has its own right to enforce its laws as it sees fit; therefore they can separately prosecute someone even if another jurisdiction has already done so based on identical facts or circumstances. This decision reaffirmed previous rulings establishing what's known as "dual sovereignty doctrine," allowing parallel prosecutions at different levels of government without violating constitutional protections against double jeopardy.

In the dissenting opinion for California v. Rooney, Justice William Brennan disagreed with the majority's decision to uphold a warrantless search of an impounded vehicle. He argued that this violated the Fourth Amendment rights against unreasonable searches and seizures. Brennan contended that there was no exigency or immediate need to justify bypassing obtaining a warrant before conducting such a search, as law enforcement had already secured control over the vehicle in question. The justice also pointed out inconsistencies between this ruling and previous Supreme Court decisions regarding similar circumstances, which he believed further undermined its validity.