Gun Quotes : Militia Meaning
At the time of the writing, the definition of militia was, "The whole body of civilians, that are NOT part of the regular army”. Since the Guard/Reserves are part of the regular army (or reserves), they are the unorganized militia (which was everyone else). Basically, anyone old enough to defend their home, town or country (that was not in the army already) was the militia.
But even today, the meaning hasn’t changed as much as some think. Some people mistakenly think it means reserves or National Guard (established 1903, and subject to federal control) — but since those didn’t exist at the time of authoring, there is no way it could have been the type of body envisioned by the framers. Today’s legal definition is, the "militia" consists of "all able-bodied males at least 17 years of age”, with a few exclusions for medical, mental or job deferments (by their choice) (10 U.S.C. 311 and 32 U.S.C. 313).
You don’t have to take my word for it, there are multiple Constitutional rulings and the words of the authors listed below — but they’re all variants of the following:
(b) The classes of the militia are - (1) the organized militia, which consists of the National Guard and the Naval Militia; and (2) the unorganized militia, which consists of the members of the militia who are NOT members of the National Guard or the Naval Militia. ❞