2nd amendment (not directly anyway), it comes from a Supreme Court decision ABOUT the 2nd Amendment called "The District of Columbia vs. Heller" . The 2nd Amendment, as written by the Founding Fathers and set down in the Bill of Rights is:
"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."
Which (until 2008 when the Washington gun lobby stepped in) has always been interpreted as "You have the right to bear arms, as long as you are serving in a militia". It was only AFTER DoC v. Heller (when the NRA flooded the case with cash) that it was re-interpreted as "You have the right to bear arms, unconnected with military service".