The landmark Heller ruling said the Constitution protects a person’s right to keep a gun in his home for purposes of self-defense, at least as against the federal government (the case was filed in the federal capital city, Washington, DC). Next, the Supreme Court ruled that the right to keep a gun in the home also had to be honored by state and local governments. The litigation has now moved on to consider whether, and to what extent, the right to keep and bear arms must be honored outside the home.

Yesterday, a federal court invalidated a Maryland law that granted carry permits only to those who could show a “good and substantial reason” for carrying a gun (general worry about the possibility of a criminal attack was inadequate). The Court said the Maryland law “impermissibly infringes the right to keep and bear arms guaranteed by the Second Amendment.”

Last month Cato released a study concerning the frequency with which persons use guns for self-defense—way more often than the average person realizes.

Cato associate policy analyst David Kopel, has more over at the Volokh blog.