By 2025, Americans owned an estimated 24 million AR-style rifles, making them the most popular firearms in the country. When the Supreme Court ruled in District of Columbia v. Heller (2008), it held that the Second Amendment protects those weapons that are in 'common use' by law-abiding citizens for lawful purposes. Courts now use this 'common use' standard to evaluate whether firearms regulations violate the Second Amendment.
This doctrine originated in the Heller decision and was reinforced in New York State Rifle & Pistol Association v. Bruen (2022). The test matters because weapons protected under 'common use' receive full Second Amendment protection, while weapons not in common use can be regulated or banned. The central dispute is whether 'common use' turns on raw ownership numbers—in which case 24 million AR-style rifles qualify almost automatically—or on a weapon's role in public safety, in which case widespread ownership of a weapon designed for rapid, high-volume fire cuts the other direction. The Supreme Court has not yet definitively ruled on whether AR-15s qualify, though several lower court cases are working their way through the federal appeals system.