The only commentary available to Congress when it ratified the Second Amendment was written by Tench Coxe, one of James Madison's friends. Explained Coxe: "The people are confirmed by the next article of their right to keep and bear their private arms."
Madison's original structure of the Bill of Rights did not place the amendments together at the end of the text of the Constitution (the way they were ultimately organized); rather, he proposed interpolating each amendment into the main text of the Constitution, following the provision to which it pertained. If he had intended the Second Amendment to be mainly a limit on the power of the federal government to interfere with state government militias, he would have put it after Article 1, section 8, which granted Congress the power to call forth the militia to repel invasion, suppress insurrection, and enforce the laws; and to provide for organizing, arming, and disciplining the militia. Instead, Madison put the right to bear arms amendment (along with the freedom of speech amendment) in Article I, section 9--the section that guaranteed individual rights such as habeas corpus. Finally, in ratifying the Bill of Rights, the Senate rejected a change in the Second Amendment that would have limited it to bearing arms "for the common defense." Gun control advocates argue that the Second Amendment's reference to the militia means that the amendment protects only official uniformed state militias (the National Guard). It is true that the Framers of the Constitution wanted the state militias to defend the United States against foreign invasion, so that a large standing army would be unnecessary. But those militias were not uniformed state employees. Before independence was even declared, Josiah Quincy had referred to "a well-regulated militia composed of the freeholder, citizen and husbandman, who take up their arms to preserve their property as individuals, and their rights as freemen." "Who are the Militia?" asked George Mason of Virginia, "They consist now of the whole people."  The same Congress that passed the Bill of Rights, including the Second Amendment and its militia language, also passed the Militia Act of 1792. That act enrolled all able-bodied white males in the militia and required them to own arms.
Although the requirement to arm no longer exists, the definition of the militia has stayed the same; section 311(a) of volume 10 of the United States Code declares, "The militia of the United States consists of all able-bodied males at least 17 years of age and . . . under 45 years of age." The next section of the code distinguishes the organized militia (the National Guard) from the "unorganized militia." The modern federal National Guard was specifically raised under Congress's power to "raise and support armies," not its power to "Provide for organizing, arming and disciplining the Militia." Indeed, if words mean what they say, it is impossible to interpret the Second Amendment as embodying only a "collective" right. As one Second Amendment scholar observed, it would be odd for the Congress that enacted the Bill of Rights to use "right of the people" to mean an individual right in the First, Fourth, and Ninth Amendments, but to mean a state's right in the Second Amendment. After all, when Congress meant to protect the states, Congress wrote "the States" in the Tenth Amendment.Moreover, several states included a similar right to bear arms guarantee in their own constitutions. If the Second Amendment protected only the state uniformed militias against federal interference, a comparable article would be ridiculous in a state constitution.