More on the Unorganised Militia

Usually, you get someone pointing to 10 USC §311(b)(2) and saying they are part of the Unorganised Militia.  Unfortunately, this section of the Code doesn't give a gloss on what exactly this means, but I have gone into it before in other posts: Asked and Answered--Unorganised, Sedentary, reserve, etcetera militias explained and Still more on the Unorganised Militia..  Basic info being:

The Sedentary, reserve, inactive, unorganised, general (or other term indicating INACTIVITY) Militia, has always been unorganized and untrained

Active Militias, that is THE organised, enrolled, embodied, active (or other term signifying active) Militia, can be supplemented if necessary by the ballot (selection by lot)--in other words drafted from the Unorganised militia draft pool.

The term "unorganized" did not begin to emerge until the 1830s and 1840s, when a massive wave of opposition destroyed the compulsory militia system. Nobody wanted to serve in the militia. State governors and legislators wanted to be able to accommodate this desire, but they were bound by the 1792 Uniform Militia Act, which stated that every white male aged 18-45 would be in the militia.

Militia service was so unpopular that Delaware abolished its militia system altogether in 1831. Massachusetts eliminated compulsory service in 1840, followed by Maine, Ohio, Vermont in 1844, Connecticut and New York in 1846, Missouri in 1847, and New Hampshire in 1851. Indiana classified its militia according to age in 1840, and exempted all but the young men from service. New Jersey withdrew the right to imprison a man for failure to pay a militia fine in 1844; Iowa did the same in 1846, Michigan in 1850, and California in 1856." - Mahon, John K, The History of the Militia and the National Guard, p. 83

The term "unorganized militia" was kept in use in subsequent decades as a statutory "reminder" that the state could still obligate its citizens to perform military duty, should it ever want them to. Eventually, U.S. law in the early twentieth century picked up this same usage for the same reason: by creating the "unorganized militia," the United States could guarantee usage of this manpower for military purposes, should the (remote) need ever arise. 

Of course, legal method would tell you that there might be another part of the US Code that addresses this issue.  In fact, Title 10 is the Section of the US Code that covers the Armed Forces and there are sections that further elaborate on this topic.  10 USC Chapter 1003 - Reserve Components Generally--specifically addresses who the national guard happens to be:

10 USC 10101
The reserve components of the armed forces are: (1) The Army National Guard of the United States. (2) The Army Reserve. (3) The Naval Reserve. (4) The Marine Corps Reserve. (5) The Air National Guard of the United States. (6) The Air Force Reserve. (7) The Coast Guard Reserve.

10 USC 10105 - Sec. 10105. Army National Guard of the United States: composition
The Army National Guard of the United States is the reserve component of the Army that consists of - (1) federally recognized units and organizations of the Army National Guard; and (2) members of the Army National Guard who are also Reserves of the Army. 

Also 10 USC § 312. Militia duty: exemptions, addresses who exempt from service in the militia. 32 USC § 313 deals with who can enlist to serve in the militia.

As I have said before, you need to actually be a member of the National Guard to actually claim that you are a member of the militia.  And that Constitutionally, the only body that can call itself a militia is one which is organised under Article I, Section 8, Clause 16--not the Second Amendment.

See also

• Legal Basis of the National Guard