Writing for the court in a case involving restrictive laws in Chicago and one of its suburbs, Justice Samuel Alito said that the Second Amendment right "applies equally to the federal government and the states."
The court was split along familiar ideological lines, with five conservative-moderate justices in favor of gun rights and four liberals opposed. Chief Justice Roberts voted with the majority.
Two years ago, the court declared that the Second Amendment protects an individual's right to possess guns, at least for purposes of self-defense in the home.
That ruling applied only to federal laws. It struck down a ban on handguns and a trigger lock requirement for other guns in the District of Columbia, a federal city with a unique legal standing. At the same time, the court was careful not to cast doubt on other regulations of firearms here.
Gun rights proponents almost immediately filed a federal lawsuit challenging gun control laws in Chicago and its suburb of Oak Park, Ill, where handguns have been banned for nearly 30 years. The Brady Center to Prevent Gun Violence says those laws appear to be the last two remaining outright bans.
Lower federal courts upheld the two laws, noting that judges on those benches were bound by Supreme Court precedent and that it would be up to the high court justices to ultimately rule on the true reach of the Second Amendment.
The Supreme Court already has said that most of the guarantees in the Bill of Rights serve as a check on state and local, as well as federal, laws.
Monday's decision did not explicitly strike down the Chicago area laws, ordering a federal appeals court to reconsider its ruling. But it left little doubt that they would eventually fall.
Still, Alito noted that the declaration that the Second Amendment is fully binding on states and cities "limits (but by no means eliminates) their ability to devise solutions to social problems that suit local needs and values."