10 U.S.C. §311: "The militia of the United States consists of all able-bodied males at least 17 years of age and, except as provided in section 313 of title 32, under 45 years of age who are, or who have made a declaration of intention to become, citizens of the United States (...) (Many modern state statutes include women in the definition of the militia.) (...)
As the Supreme Court said in United States v. Miller, "The debates in the Convention, the history and legislation of Colonies and States, and the writings of approved commentators ... show plainly enough that the Militia comprised all males physically capable of acting in concert for the common defense. ... And further, that ordinarily when called for service these men were expected to appear bearing arms supplied by themselves and of the kind in common use at the time."
Gee, I hope they're not throwing that piece of logic to the wind. Old people like MODU and disabled people like J.J. clearly have no constitutional right to bear arms based on this. (although of course the 45 cutoff is arbitrary and could easily be found unconstitutional.)
No, it says that I don't have to join the Militia. I wouldn't suggest that al Qaeda count on me opting out.