The Supreme Court has just announced its decision in District of Columbia v. Heller, a case about the constitutionality of Washington, D.C.'s ban on handguns. In an opinion written by conservative Justice Antonin Scalia, the court affirmed a lower court's ruling on the case; that ruling struck down the ban, and said that the Second Amendment protects an individual right to bear arms.

This is the first time the court has ruled on the meaning of the Second Amendment since 1939.

I'll have more on this case shortly, once the opinion itself comes out on the Internet.

Update: Just to clarify a bit, the key question the Supreme Court decided today was what exactly the Second Amendment means. The amendment reads, "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." There has been quite a bit of debate historically about the significance of that "well regulated militia" bit, not to mention the odd placement of the commas.

During oral arguments in the case, former Solicitor General Walter Dellinger, arguing on behalf of D.C., said that the amendment protects "a right to participate in the common defense."

The court disagreed, and found -- for the first time -- that the amendment protects an individual right to bear arms.

The ruling also said that laws that require a trigger lock on guns kept in the home are unconstitutional, as such locks might restrict the owner's ability to use the gun "for the purpose of immediate self-defense."

However, Scalia was careful not to strike down all gun laws. "The Second Amendment does not protect those weapons not typically possessed by law-abiding citizens for lawful purposes, such as short-barreled shotguns," Scalia wrote. Additionally, he said, "nothing in our opinion should be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms." Licensing requirements were also held to be constitutional.

Update 2: This was a 5-4 decision. Voting in the majority, along with Scalia, were Chief Justice John Roberts and Justices Anthony Kennedy, Clarence Thomas and Samuel Alito. There were two dissenting opinions. The first was written by Justice John Paul Stevens and joined by Justices David Souter, Ruth Bader Ginsburg and Stephen Breyer. The second was written by Breyer and joined by Stevens, Souter and Ginsburg.