What right does amendment 2 protect?

Answer 1

The right to keep and bear arms.

The question that came is whether the 2nd Amendment was a "collective right," that is, a right guaranteed to the states (like the right to a republican form of government), or whether it was an "individual right" (like the right not to have one's home searched by the government absent a warrant.)

This question should have been settled when the U.S. Supreme Court heard United States v. Miller, 307 U.S. 174(1939), in which it was asked to decide whether a sawed-off shotgun was a legitimate weapon. If the 2nd Amendment was only a collective right, the Supreme Court would not have heard the case in the first place (Miller was not a State) and he wouldn't have had standing to raise the 2nd Amendment. However, Miller died before the case was heard, so his side did not send anyone to argue. As a result, 70 years of law on the subject went both ways in various courts,some deciding the Second supported only a collective right, while others deciding the Second fully supports an individual right, until the Supreme Court confirmed what it has always held, that the Second Amendment was an individual right.

NOTE: the debate on if this is just the militia or not is well settled in courts, that it is not - and several hundred pages of quotes can be put here by these courts:

All of the evidence indicates that the Second Amendment, like other parts of the Bill of Rights, applies to and protects individual Americans. We find that the history of the Second Amendment reinforces the plain meaning of its text, namely that it protects individual Americans in their right to keep and bear arms whether or not they are a member of a select militia or performing active military service or training. We reject the collective rights and sophisticated collective rights models for interpreting the Second Amendment. --- U.S. vs. Emerson, 270 F.3d 203 (5th Cir. 2001)

This decision differed from the other circuits who considered the Second was only a right of the states against the federal government depriving them of a militia, and not a right of individuals. The Supreme Court in Heller v. District of Columbia, 554 U.S. 570 (2008) found the rights under the Second Amendment are the rights of individuals, not a collective right or a right of the States.

Some wondered whether the Second Amendment was only applicable to Congress or was it also a right one could invoke against a state. The Supreme Court held the Second Amendment to be applicable to the states, McDonald v. Chicago, 561 U.S. ___, 130 S.Ct. 3020 (2010).

Answer 2

It gives the right for a well-regulated militia to bear arms. Grab a copy of the constitution and read it.