Militia Members

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
Article IV
Bill of Rights

United States Code: Title 10 – Armed Forces
Subtitle A – General Military Law
Chapter 13 – The Militia

Sec. 311. Militia: composition and classes

• (a) 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 and of female citizens of the United States who are members of the National Guard.
• (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

Note that other than age, health, gender, or citizenship, there are no additional provisions for exemption from membership in the unorganized militia.