What does the Second Amendment actually say and mean?

The text reads that a well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed. The relationship between the opening clause and the operative clause was contested for most of American history, with one reading treating the right as tied to militia service and the other treating it as an individual right that the militia clause explains but does not limit. For decades the Supreme Court said little, and lower courts largely followed the militia-linked reading.

District of Columbia v. Heller in 2008 resolved that dispute, holding five to four that the Second Amendment protects an individual right to possess firearms unconnected to militia service, at least for self-defense in the home. McDonald v. City of Chicago in 2010 applied that right against state and local governments through the Fourteenth Amendment. Heller also stated explicitly that the right is not unlimited, listing presumptively lawful measures including prohibitions on possession by felons and the mentally ill, bans in sensitive places such as schools and government buildings, and conditions on commercial sale.

New York State Rifle and Pistol Association v. Bruen in 2022 changed how courts evaluate gun regulations, rejecting the balancing approach lower courts had used and requiring the government to show that a challenged regulation is consistent with the nation's historical tradition of firearm regulation. That test has generated substantial litigation and inconsistent results as courts work out which historical analogues count and how closely they must match, and the Court has since revisited its application. The practical landscape therefore remains unsettled and varies considerably by circuit and by state, which is why specific questions about what is lawful where require current local legal advice rather than general principles.