the bill of rights. Amendments 2 & 10
the 2nd amendment states "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". This means that the people have a right to own guns and defend themselves and that the government cannot take away this right.
the 10th amendment says " the power not delegated to the united states by the Constitution, nor prohibited by the states, are reserved to the states respectively, or to the people. this means that any power that is not given to the government is given to the people.