Second Amendment
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.
Where the Second Amendment comes from
In 1786, the United States existed as a loose national government under the Articles of Confederation. This confederation was perceived to have several weaknesses, among which was the inability to mount a Federal military response to an armed uprising in western Massachusetts known as Shays' Rebellion.
In 1787, to address these weaknesses, the Philadelphia Convention was held with the idea of amending the Articles. When the convention ended with a proposed Constitution, those who debated the ratification of the Constitution divided into two camps; the Federalists (who supported ratification of the Constitution) and the Anti-Federalists (who opposed it).
Among their objections to the Constitution, anti-Federalists feared a standing army that could eventually endanger democracy and civil liberties. Although the anti-Federalists were unsuccessful at blocking ratification of the Constitution, through the Massachusetts Compromise they insured that a Bill of Rights would be made, which would provide constitutional guarantees against taking away certain rights.
One of those rights was the right to bear arms. This was intended to prevent the Federal Government from taking away the ability of the states to raise an army and defend itself.
Comments
The meaning of this amendment is controversial with respect to gun control.
The National Rifle Association, which supports gun rights, has a stone plaque in front of its headquarters bearing the words "The right of the people to keep and bear arms shall not be infringed." The slogan means that individual citizens have the right to own and use guns.
The problem is that when the entire sentence is quoted, the first part makes it sound as if the amendment is talking only about the militia. The phrase "the people" can be read as meaning "the states."
American law has always said that the militia includes ordinary private citizens, and gun rights advocates say that the amendment means individuals have the right to own and use guns. Gun control advocates say it means only that there is only some sort of collective or state-controlled right.
Supreme Court opinions have all been consistent with the individual rights interpretation of the Second Amendment, but the lower court opinions are mixed.
As of 2007, people argue about the meaning of the Second Amendment, but there is no definitive answer. The latest ruling is Parker v District of Columbia, in which the DC Circuit court of appeals ruled on March 9, 2007 that the DC gun ban violated individual rights under the Second Amendment.