The Second Amendment says: "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."
As a nation mourns deaths from the massacre of school children in Connecticut, and a pro-gun lawmaker says assault weapons should be curbed and President Obama says more needs to be done to prevent such killings, we have been thinking about the history of the right of Americans to bear arms.
In April, The New Yorker called the Second Amendment our Lost Amendment, noting "no amendment received less attention in the courts in the two centuries following the adoption of the Bill of Rights than the Second, except the Third (which dealt with billeting soldiers in private homes)."
Still, there is an interesting history here, including a mention in the Dred Scott case in 1857, when the Supreme Court ruled against affording slaves full rights of American citizenship. The court noted that citizenship would include the right of slaves “to keep and carry arms wherever they went.” (See paragraph 77)
The first major gun-control legislation was passed in the early 1930s and was a result, in part, of another mass shooting: the Saint Valentine's Day massacre in 1929.
But it wasn't until 2008 that the U.S. Supreme Court decided the fundamental question that the amendment's language leaves room for debating: Does everyone have a right to carry a weapon and use it for lawful purposes?
Yes, the court said, in District of Columbia v. Heller, which tied gun ownership to a right of self-defense. (Heller applied to the federal government while a 2010 case made the same conclusion for state and local governments.) The written opinion and dissents show both sides in the 5-4 decision wrestling with the very meaning and weight of the Second Amendment's words adopted more than two centuries ago.
Wikipedia also has a good background on Heller, which incorporates plenty of history on the Second Amendment. Its own background page on the amendment is here.