Washington DC had a set of gun laws that made owning a handgun illegal without a special one-year permit. An additional lock-and-trigger requirement prohibited keeping loaded “fire-ready” guns in DC homes. A policeman, Dick Heller, applied for a permit to possess a handgun in his Washington home. After being denied a permit, Heller sued the city using an argument under the Second Amendment that DC’s laws deprived him of the right to a handgun for self-defense and the lock-and-trigger requirement effectively banned useful firearms from the home. In 2008 Heller’s argument prevailed at the Supreme Court with a 5-4 vote. In District of Columbia v. Heller, the Supreme Court rejected the view that the Second Amendment only applied to militias. For the first time, the Court held that the Second Amendment conveyed an individual right to gun ownership and that to protected possession of guns in the home. Prior to Heller, the court in US v. Miller limited Second Amendment protection to weapons useful to militias and did not extend the right to individuals. The court conducted a more thorough review in Heller and found handguns to be protected by the historical extent of the Second Amendment’s purpose, and struck down the DC’s ban. It also struck down the city’s trigger-lock mandate because it rendered guns in the home useless for the self-defense purpose protected by the individual right. Justice Scalia, writing for the majority, reasoned that the effect of the requirement amounted to a ban on guns in the home.

Because DC is a federal enclave, however, the Heller decision established a narrow precedent. In 2010 the Supreme Court decided its next major Second Amendment case, McDonald v. Chicago. That case was brought by Otis McDonald, who sought to apply the Second Amendment Heller right to local and state governments by suing the City of Chicago over laws similar to those at issue in Heller. Justice Alito, who authored the Court’s opinion, found that the individual right was one historically regarded as a “substantive guarantee,” and one that the majority of the states recognized in some manner. In a 5-4 opinion a majority of the Court found that the individual right pronounced by Heller was incorporated by the Fourteenth Amendment and fully applied to the states. The plurality of the Court reasoned the Second Amendment right from Heller applied to the states through the Fourteenth Amendment‘s Due Process Clause. Justice Thomas, who concurred in part and concurred in judgment, reasoned that Fourteenth Amendment’s Privileges and Immunities Clause applied Heller‘s to the states.