Assault weapons ban

An assault weapons ban prohibits specified semi-automatic rifles, and sometimes pistols and shotguns, defined by features such as pistol grips, folding stocks, flash suppressors and detachable magazines, and often limits magazine capacity. "Assault weapon" is a legal and political term, not a technical military one; true assault rifles are capable of automatic fire and are already tightly regulated under the National Firearms Act.

Congress enacted a federal ban as part of the 1994 crime bill. It banned 19 named models and weapons with two or more listed features, with a ten-year sunset, and expired in 2004. Studies of its effect on crime were inconclusive. A number of states, including California, New York, Illinois and Washington, have their own bans, and bills to restore a federal ban have repeatedly been introduced.

Supporters argue that the weapons are used disproportionately in mass shootings and that limiting them and high-capacity magazines would reduce casualties. Opponents argue that the rifles such as the AR-15 are widely owned for lawful purposes including self-defense and sport, that the definitions are arbitrary and that rifles of any kind are used in a small fraction of gun deaths. Courts have split on whether the bans are consistent with District of Columbia v. Heller and the test in New York State Rifle & Pistol Association v. Bruen, and the Supreme Court has so far declined to take a case.