By Robert Barnes and Dan Eggen
Washington Post Staff Writer

The Second Amendment provides Americans a fundamental right to bear arms that cannot be violated by state and local governments, the Supreme Court ruled Monday in a long-sought victory for gun rights advocates.

The 5 to 4 decision does not strike down any gun-control laws in place, nor does it elaborate on what kind of laws would offend the Constitution. One justice predicted that an "avalanche" of lawsuits would be filed across the country asking federal judges to define the boundaries of gun ownership and government regulation.

But Justice Samuel A. Alito Jr., who wrote the opinion for the court's dominant conservatives, said: "It is clear that the Framers . . . counted the right to keep and bear arms among those fundamental rights necessary to our system of ordered liberty."

The decision extended the court's 2008 ruling in District of Columbia v. Heller that "the Second Amendment protects a personal right to keep and bear arms for lawful purposes, most notably for self-defense within the home." That decision applied only to federal laws and federal enclaves such as Washington; it was the first time the court had said there was an individual right to gun ownership rather than one related to military service.

Monday's decision might be more symbolic than substantive, at least initially. No cities have laws as restrictive as the handgun bans in the District and in Monday's case from Chicago and its suburb of Oak Park. Although the court's decision did not specifically strike those laws, Chicago Mayor Richard M. Daley said it would make the city's 28-year-old law "unenforceable."

Those who have fought for years for such an interpretation of the Second Amendment were ecstatic. "A great moment in American history," said Wayne LaPierre, executive vice president of the National Rifle Association, marking the occasion when "the Second Amendment becomes a real part of constitutional law."

The decision came on a typically frenetic last day of the court's term. But it was also one marked by sadness, melancholy and change.

Bow ties popped up on men and woman throughout the courtroom, a tribute to Justice John Paul Stevens, 90, who first came to work at the court 63 years ago as a clerk. He is retiring from the seat he assumed on Dec. 19, 1975, and said in a letter to his colleagues that "if I have overstayed my welcome, it is because this is such a unique and wonderful job."

Also on the bench was Justice Ruth Bader Ginsburg, whose husband of 56 years, Martin D. Ginsburg, died on Sunday. Ginsburg, 77, looked directly ahead as Chief Justice John G. Roberts Jr. recounted Martin Ginsburg's accomplishments as a renowned tax attorney and university professor, and she smiled sadly when Roberts mentioned her husband's skills as a "gourmet cook."

The court's gun decision in McDonald v. Chicago divided the nine justices just as the Heller case had done almost exactly two years earlier. Roberts and Alito were in the majority with Justices Antonin Scalia, Anthony M. Kennedy and Clarence Thomas. Stevens and Ginsburg dissented, along with Justices Stephen G. Breyer and Sonia Sotomayor, who was marking her first term replacing David H. Souter.

States and cities have a variety of laws placing restrictions on gun ownership, such as requiring mental health background checks or waiting periods before gun purchases. And the court's designation of the individual right to gun ownership as a fundamental right, like freedom of speech, will provide a tool for those who want to challenge restrictive local laws. Subsequent legal battles may set national guidelines on restrictions on who can own guns, what kind of guns and whether weapons can be carried outside the home.

Alito said the court had made clear in its 2008 decision that it was not casting doubt on such long-standing prohibitions on gun possession by felons and the mentally ill, or keeping guns out of "sensitive places" such as schools and government buildings.

"We repeat those assurances here," Alito wrote. "Despite municipal respondents' doomsday proclamations, [the decision] does not imperil every law regulating firearms."

Dennis A. Henigan, vice president for law and policy at the Brady Center to Prevent Gun Violence, noted that the District has survived a legal challenge to a new system of regulations implemented after Heller, including mandatory background checks, firearms training and other requirements for gun ownership.

"When you look at all these categories of presumptively legal gun laws, it's actually hard to find any regulation that doesn't fit into one of those categories other than the handgun bans that are now off the table," Henigan said. "Over the long run, this apparent victory for gun rights may be more symbol than substance. It's actually a very narrow holding."

But the Gun Owners of America, which fashions itself as a more conservative alternative to the NRA, predicted "tremendous ramifications" for gun-control laws in California, New York and elsewhere.

New York Mayor Michael R. Bloomberg (I), who has joined other big-city mayors in advocating tougher gun restrictions, said the Heller and McDonald rulings "both make clear that we can work to keep guns out of the hands of criminals and terrorists while at the same time respecting the constitutional rights of law- abiding citizens. That's what New York City has always done."

Stevens said the decision "invites an avalanche of litigation that could mire the federal courts in fine-grained determinations about which state and local regulations comport with the Heller right -- the precise contours of which are far from pellucid -- under a standard of review we have not even established."

Justice Stephen G. Breyer objected to the majority decision and read his dissent from the bench. He disagreed with the majority that it is a fundamental right, saying the court was restricting state and local efforts from designing gun-control laws that both fit their particular circumstances and save lives.

"In a nation whose constitution foresees democratic decision-making, is it so fundamental a matter as to require taking that power from the people?" Breyer wrote. "What is it here that the people did not know? What is it that a judge knows better?"

Although it might seem unsurprising to most that the Bill of Rights applies to states and cities, it was conceived as a restriction on the federal government. In the past century, the court has said most of the amendments also apply to state and local governments.

Until Monday, the court had not extended the Second Amendment, which holds that "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."

Four members of the majority said the amendment was "incorporated" through the 14th Amendment's guarantee that the states may not "deprive any person of life, liberty, or property, without due process of law."

Thomas agreed with the outcome of the case but said the right was more correctly located elsewhere in the 14th Amendment, in a clause that forbids laws that abridge "the privileges or immunities of citizens of the United States."