Printz v. United States (1997)

The Brady Handgun Violence Prevention Act, signed on November 30, 1993, created a national system of background checks for gun purchases. Until a federal computerized system was ready, the act's interim provisions required local chief law enforcement officers to make a reasonable effort to determine within five business days whether a proposed purchase would be lawful. Two sheriffs, Jay Printz of Ravalli County, Montana, and Richard Mack of Graham County, Arizona, challenged the requirement as an unconstitutional command to state officials.

On June 27, 1997, the Supreme Court ruled 5 to 4, in an opinion by Justice Antonin Scalia, that the federal government may not command the states' officers, or those of their political subdivisions, to administer or enforce a federal regulatory program. Building on New York v. United States in 1992, which barred commandeering state legislatures, Scalia relied on the Constitution's structure, early history, and the principle of dual sovereignty, reasoning that commandeering blurs accountability and lets Congress shift costs to the states. Justice John Paul Stevens, in dissent, argued that the framers expected federal use of state officials.

The background checks continued voluntarily in most places until the National Instant Criminal Background Check System began on November 30, 1998. Printz is the basis for the principle that states and cities may decline to help enforce federal law, including immigration detainer requests, which underlies sanctuary policies, and for Murphy v. NCAA in 2018. Defenders say it protects state sovereignty and political accountability, while critics say it hampers national enforcement and is invoked selectively by whichever side opposes a given federal policy.