Recent mass shootings reignited the debate over legislation to combat gun violence. Here's a look at laws already on the books in the United States dealing with firearms.
1791 -- Second Amendment: Congress ratifies the Second Amendment to the Constitution, which 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."
1934 -- National Firearms Act: The law was designed to make it difficult to obtain especially lethal guns. These would include preferred weapons of the era's gangsters, like sawed-off long rifles or shotguns and machine guns. It also regulated specialty weapons concealed in canes, pens or other items.
1968 -- Gun Control Act of 1968: Following the assassinations of President John F. Kennedy, Rev. Martin Luther King Jr. and Sen. Robert F. Kennedy, Congress passed this law prohibiting convicted felons from possessing firearms. It also required licenses to trade in guns and created procedures to track serial numbers and control imports.
1984-1986 -- Comprehensive Crime Control Act and the Armed Career Criminal Act: These laws enhanced penalties for using or carrying firearms while committing serious drug offenses, for felons with three prior convictions of violent crimes or drug offenses, for using short-barreled rifles and shotguns and semiautomatic weapons and for automatic weapons or those equipped with a silencer.
1986 -- The Firearms Owners' Protection Act of 1986: Allowed licensed dealers to operate outside of their normal places of business, like gun shows, and excluded hobbyists or collectors from some regulations. It permitted sales of ammunition without a license, allowed convicted felons to obtain guns if their civil rights were restored after prison, and banned the production of machine guns for civilian use. It also made it illegal for anyone to sell firearms to those prohibited from owning them.
1993 -- The Brady Law: After a seven-year legislative battle, Congress passed the Brady Handgun Violence Protection Act, which required background checks for those buying firearms.
1994 -- Violent Crime Control and Law Enforcement Act: Increased fees and required photographs and fingerprints to obtain a dealer's license.
1994 -- Youth Handgun Safety Act: Banned possession of handguns by those under 18 and prohibited adults from transferring them to juveniles.
1994 -- Assault weapon ban: The Violent Crime Control and Law Enforcement Act made it unlawful, with a few exceptions, to make, transfer, or possess semiautomatic assault weapons. It also made it illegal to possess large capacity magazines that held more than 10 rounds. The law expired in 2004.
Sources: U.S. Department of Justice; Congressional Research Service