The case the Justices will hear this spring is an appeal from the District of Columbia, whose gun-control lawthe strictest in the nationwas struck down by a lower federal court last year.
"This case is very likely to produce the most significant Supreme Court decision on the Second Amendment in our history," says Dennis Henigan, vice president of the Brady Campaign to Prevent Gun Violence.
Individuals or Militias?
In more than 200 years, the Court has never decided the fundamental question of whether the Second Amendment refers to individuals or militias. Where the Justices come down on this issue will have a huge impact on federal, state, and local gun-control laws.
One of the most disputed passages in the Constitution, the Second Amendment states, in its entirety: "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."
The Supreme Court has never directly addressed the basic meaning of those words. When it last considered a Second Amendment case, United States v. Miller, in 1939, the Court addressed a peripheral question, holding that a sawed-off shotgun was not one of the "arms" that the Founding Fathers had in mind.
The 1939 ruling suggested, without explicitly deciding, that the Second Amendment right should be understood in connection with service in a militia. That ruling helped support a scholarly and judicial consensus that the Second Amendment protects only the right of the states to maintain militiasand served as the legal basis for federal, state, and local gun-control laws regulating individual ownership of guns.
For three decades, starting in the 1960s, the story of gun control was one of notorious crimes and laws passed in response, beginning with the 1968 federal gun-control law that followed the assassinations of Senator Robert F. Kennedy and Martin Luther King Jr. In 1994, Congress passed an assault weapons ban and created a national system of background checks for gun buyers.
Today, there are some 280 million firearms in private hands in the U.S., and about 30 percent of American households report having a gun at home.
Advocates of gun-control laws say much has changed since the nation's founding, when people kept muskets to be ready for militia service and to hunt for their food. Today, militias have disappeared and hunting is largely recreational.
And modern weapons are far deadlier than those of the 18th century: They fire more powerful ammunition and can deliver dozens of shots at a time. In 2004, almost 30,000 Americans died from gun violence, more than in any other country.
Gun-rights groupsthe most powerful of which is the National Rifle Associationargue that any restrictions on gun ownership infringe upon the rights of law-abiding citizens.
"The only universe of people affected by gun-control laws are law-abiding Americans, since most criminals obtain their firearms on the black market," says Andrew Arulanandam of the N.R.A.
The N.R.A. believes that the Founding Fathers intended the Second Amendment to be a right that applies to individualslike the other rights guaranteed in the Bill of Rights.
The case before the Supreme Court involves a Washington, D.C., law that makes it very difficult to legally own a handgun. The case, District of Columbia v. Heller, will likely be argued before the Justices in the spring and decided in June.
Washington's Gun Law
The plaintiff in the case is Dick Anthony Heller, a security guard who carries a gun while on duty guarding a federal office building. Heller wants to be able to keep his gun at home for self-defensesomething the D.C. law prohibits.
Of the nation's hundreds of state and local gun regulations, the D.C. ordinance is considered the strictest. Chicago comes the closest to it, banning the possession of handguns acquired since 1983 and requiring re-registration of older guns every two years. New York City allows handgun ownership with a permit issued by the Police Department.
The D.C. law not only bans ownership of handguns, but also requires that rifles, shotguns, and other guns that can be kept in homes be disassembled or kept under a trigger lock.
Linda Singer, the District of Columbia Attorney General, says the meaning of the Second Amendment, which is at the heart of the Supreme Court case, is not an academic debate for Washington residents.
"It's truly a life-or-death question for us," she says. "It's not theoretical. We all remember very well when D.C. had the highest murder rate in the country, and we won't go back there."
Even if the Supreme Court finds the D.C. law unconstitutional, that would not necessarily invalidate other, more modest gun restrictions, like those that permit handgun ownership for those who pass a background check and obtain a license.
In fact, lawyers on both sides of the case agree that a victory for the plaintiff in this case would amount to the opening chapter in an examination of the constitutionality of gun control rather than anything close to the final word.
Alan Gura, the lead counsel for the plaintiff in District of Columbia v. Heller, agrees: "This is just the beginning."