The Second Amendment 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."
Some analysts read the amendment as providing for an armed populace and say the first clause is an explanatory statement of the necessity of having an effective military force at the state level – independent of the national government.
Other analysts see the first clause limiting the scope of the right to possess and use weapons to enrolled service in a state-regulated militia.
The Founding Fathers didn't simply write the Constitution. They also had to sell it to reluctant state residents who were fearful that the army of the national government might become as oppressive as the British military. The Second Amendment seeks to answer that fear.
Under the new government, each of the states would retain their ability to organize their own militia. The basic building block of the militia was an able-bodied citizen who reported for state military service, sometimes with his own military-grade weapon.
At issue in the Heller case is to what extent the Second Amendment applies to the private possession of guns in a modern American city.
A federal appeals court in March struck down Washington's handgun ban because it violated what the court said was an individual right to firearms. The city is asking the Supreme Court to overturn the appeals court's 2-to-1 decision.
"This is the first time in the nation's history that a federal appellate court has invoked the Second Amendment to strike down any gun control law," writes the city's Solicitor General Todd Kim in his brief to the court.
Nine other federal appeals courts and the highest local court in Washington have declined to embrace an individual-rights view of the Second Amendment, Mr. Kim writes. The decision "drastically departs from the mainstream of American jurisprudence," he says.
"Only this court can resolve these conflicts about the central meaning of the Second Amendment," Kim's brief says. It adds that the issue is "quite literally a matter of life and death" because of the dangers posed by handguns.