I have heard opponents argue that the second-amendment’s “well-regulated militia, being necessary to the security of a free state” is subsumed by the National Guard such that there is no right for citizens to organize lay-militia. Without expressing an opinion on lay-militia and para-militia groups, I’m not convinced that the subsuming approach is correct.
The adjacent Fifth Amendment has specific language that perhaps better illuminates the Framers’ conceptualization of “militia.” It reads: “No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a grand jury, except in cases arising in the land or naval forces, or in the militia, when in actual service in time of war or public danger;” Through this prose, the Framers distinguish “militia” from rank-and-file “land” (Army, Marines, Air Force) and “naval” (Navy, Coast Guard). Depending on how one interprets the text’s commas, it also suggests that militia could be “in actual service in time of war” but not necessarily that a “militia” must serve in congressionally-declared war which is fundamentally different than the National Guard, active reservists, and inactive reservists. The wording of this amendment also speaks “militia” serving in a time of “public danger.” While this does seems to describe routine duties of the National Guard, it could just as easily describe well organized neighborhood watches who ambush foreign invaders or who defend their neighborhood or community from civil unrest where rioters, arsonists, and looters cannot be held in check by the executive government.
Such service requires armament equal to that of posed by “public danger.”