The Second Amendment (Amendment II) to the United States Constitution is the part of the United States Bill of Rights that protects the right of the people to keep and bear arms. It was adopted on December 15, 1791, along with the rest of the Bill of Rights.

In 2008 and 2010, the Supreme Court issued two Second Amendment decisions. In District of Columbia v. Heller (2008), the Court ruled that the Second Amendment protects an individual's right to possess a firearm, unconnected to service in a militia^[1][2] and to use that arm for traditionally lawful purposes, such as self-defense within the home. Additionally, the Court enumerated several longstanding prohibitions and restrictions on firearms possession that it found were consistent with the Second Amendment.^[3] In McDonald v. Chicago (2010), the Court ruled that the Second Amendment limits state and local governments to the same extent that it limits the federal government.^[4]

resource from  http://en.wikipedia.org/wiki/Second_Amendment_to_the_United_States_Constitution