The US Supreme Court is considering a landmark legal battle over gun rights, taking up for the first time in nearly 70 years whether Americans have the right to keep and bear arms.
The court's ruling, expected by the end of June, could have a far-reaching impact on gun control laws in the United States, estimated to have the world's highest civilian gun ownership rate, and could become an issue in the November election.
At issue is whether to strike down or uphold one of the nation's strictest gun control laws - a Washington, DC, ban on private possession of handguns and a requirement that any rifles or shotguns kept at home be unloaded and dissembled or bound by a trigger lock.
The case is widely viewed as one of the most important of the Supreme Court's current term, along with cases on the rights of the Guantanamo Bay prisoners and the US lethal injection method of execution.
The case could resolve the much-disputed meaning of the Second Amendment of the US Constitution and whether it protects an individual's right to possess guns or a collective right of the people for service in a state militia.
The Supreme Court's last review of the Second Amendment came in a five-page discussion in an opinion issued in 1939 that failed to definitively resolve the constitutional issue.
The arguments follow a series of mass shootings in the past year - multiple killings on at least three college campuses, two shopping centres and one Missouri town meeting. Gun deaths average 80 a day in the United States, 34 of them homicides, according to centres for Disease Control data.
The case has split the Bush administration.
Solicitor General Paul Clement, the administration's chief advocate before the Supreme Court, has adopted the position that individuals have a right to own a gun, but it is subject to reasonable government regulation.
Clement, who is arguing before the justices, seeks to preserve all of the current federal restrictions, including a ban on new machine gun sales, a ban on felons owning guns and required background checks for new buyers of handguns.
But Vice President Dick Cheney joined a group of US House of Representatives and Senate members in urging the court to adopt a stronger stand in favour of gun rights.
Walter Dellinger, the attorney defending the Washington law, argued the Second Amendment protected only militia-related firearms rights.
But even if an individual has the right to possess guns, the law should be upheld as a reasonable restriction, he said.
The third attorney scheduled to appear at the arguments, Alan Gura, said the law should be struck down. He represents Dick Anthony Heller, who lives in a high-crime neighbourhood and wants to keep a handgun for self-defence.