After half a century of silence on the issue, the U.S. Supreme Court will tell Americans whether gun ownership is their right under the Second Amendment or a privilege that lawmakers can revoke.

In deciding yesterday to review whether a handgun ban in the nation’s capital violates the Bill of Rights, the federal high court has reopened one of the most divisive questions in national politics. The gun control debate cuts most cleanly along the urban and rural divide.

The Second Amendment reads, 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 not said conclusively whether those words give private citizens the right to own guns or whether they give states a right to organize an armed militia. The court last took a Second Amendment case in 1939 and failed then to provide an answer that satisfied either side in the debate over guns. In that case, United States v. Miller, which challenged a federal law requiring the registration of sawed-off shotguns, the federal high court “sidestepped the issue,” Chief Justice Roberts said during his confirmation hearing in 2005.

Earlier this year, the federal appellate court in Washington, D.C., whose decision is now under review, struck down that city’s ban on handguns, which is perhaps the nation’s most restrictive, on the grounds that the Second Amendment gives, at a minimum, individuals the right to possess a firearm in their own homes. Yesterday, Mayor Giuliani released a statement urging the Supreme Court to affirm that decision, calling it “an excellent example of a judge looking to find the meaning of the words in the Constitution, not what he would like them to mean.”

A Supreme Court decision acknowledging an individual right would prompt a wave of lawsuits challenging state and municipal gun control laws across the nation, lawyers said yesterday. Because the current case challenges a Washington law, enacted by the city council there in 1976, the case does not call into question whether the Second Amendment restricts not only the federal government, but also states from passing laws restricting gun ownership.

The current case “doesn’t necessarily have any obvious consequence for New York’s laws,” a law professor at New York University who has written on gun control laws, James Jacobs, said. The legal director at the Brady Center to Prevent Gun Violence, Dennis Henigan, said that a Supreme Court affirmance sets the stage for gun rights advocates to “challenge local and state gun laws arguing that if the Second Amendment is a fundamental right, it should be applied to the states.”

Mr. Henigan said that “reasonable regulation” of guns would be compatible with even a Supreme Court decision finding gun ownership to be an individual right.

In New York City, private citizens can keep handguns if they have a license from the police department. The department does not publicize what guidelines it uses to grant licenses and some applicants hire a lawyer to help them navigate the process.

The case is District of Columbia v. Heller. The plaintiff, Dick Anthony Heller, is a court security guard who applied for a license to carry his on-duty gun at home but was denied.

At issue in the case, the chief lobbyist for the National Rifle Association, Chris Cox, said, is whether “law-abiding citizens have the right to keep a firearm in their home to defend themselves. This is about whether or not good people have a right to defend themselves against bad people.”