Mr. Heller was one of six plaintiffs recruited by a wealthy libertarian lawyer, Robert A. Levy, who created and financed the lawsuit for the purpose of getting a Second Amendment case before the Supreme Court. The appeals court threw out the other five plaintiffs for lack of standing; only Mr. Heller had actually applied for permission to keep a gun at home and been turned down.

The Supreme Court last looked at the Second Amendment nearly 70 years ago in United States v. Miller, a 1939 decision that suggested, without explicitly deciding, that the right should be understood in connection with service in a militia. The Second Amendment provides: “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 justices chose their own wording for what they want to decide in the new case, District of Columbia v. Heller, No. 07-290. The question they posed is whether the provisions of the statute “violate the Second Amendment rights of individuals who are not affiliated with any state-regulated militia, but who wish to keep handguns and other firearms for private use in their homes.”

The court’s choice of words is almost never inadvertent, and its use of the phrase “state-regulated militia” was somewhat curious. The District of Columbia, of course, is not a state, and one of the arguments its lawyers are making in their appeal is that the Second Amendment simply does not apply to “legislation enacted exclusively for the District of Columbia.”

For that matter, the Supreme Court has never ruled that the Second Amendment even applies to the states, as opposed to the federal government. The court has applied nearly all the other provisions of the Bill of Rights to the states, leaving the Second Amendment as the most prominent exception. The justices evidently decided that this case was not the proper vehicle for exploring that issue, because as a nonstate, the District of Columbia is not in a position to argue it one way or another.