Supreme Court extends anti-commandeering doctrine to law enforcement in Printz v. United States

The Supreme Court struck down the Brady Act's requirement that county sheriffs conduct background checks on handgun purchasers while a federal database was being built. Justice Scalia's 5-4 majority opinion held that the federal government cannot conscript state and local law enforcement officers to administer a federal regulatory scheme. The ruling directly established the constitutional foundation for local police departments to refuse ICE detainer requests decades later.