The ruling specifically focused on the militia aspect militia. Quoting that ruling: The prefatory clause comports with the Court’s interpretation of the operat

The ruling specifically focused on the militia aspect militia. Quoting that ruling: The prefatory clause comports with the Court’s interpretation of the operative clause. The "militia" comprised all males physically capable of acting in concert for the common defense. The Antifederalists feared that the Federal Government would disarm the people in order to disable this citizens’ militia, enabling a politicized standing army or a select militia to rule. The response was to deny Congress power to abridge the ancient right of individuals to keep and bear arms, so that the ideal of a citizens’ militia would be preserved. People conflate militia now a days with military, but they are not the same. The "militia" are the armed citizens of a state. And similarly the security of a free state is talking explicitly about security against government itself - not foreign invaders, which was the domain of the federal government. An armed population can prevent the imposition of tyrannical rule, an unarmed population cannot. In verbose modern text the amendment might read something like, "A well regulated and armed population being necessary for the protection of a state against tyranny, the right of the people to keep and bear arms shall not be infringed."