Ratified without controversy in 1791, the Second Amendment to the United States Constitution reads: “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.” It applied only to the federal government, leaving the states with their pre-existing authority over the regulation of weapons. Although some states adopted a few limited restrictions during the antebellum period, the federal government first enacted significant regulations in a 1934 law that subjected certain firearms to a steep tax and a registration requirement. In United States v. Miller (1939), the Supreme Court issued a narrow decision dealing only with the type of weapons that individuals have a right to keep and bear, namely those that have “some reasonable relationship to the preservation or efficiency of a well regulated militia.”

In the following decades, the federal courts upheld every law that was challenged under the Second Amendment. In District of Columbia v. Heller (2008), the Supreme Court broke new ground, invalidating a regulation that banned the possession of handguns in the nation’s capital. Two years later, in McDonald v. City of Chicago, the Court rejected a similar regulation, holding that the 14th Amendment (ratified in 1868) made the Second Amendment applicable to