The right to bear arms, as established by the Second Amendment, formally reads as -  “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.” There have been many debates on the meaning of this amendment and it has been interpreted in several ways in Supreme Court rulings. While some believe that the phrase "the right of the people to keep and bear arms" creates a constitutional right for the US citizens, others opine that "a well-regulated Militia" intends to restrict Congress from legislating away a state's right to self-defense. You may read more about it here.