Members of the "Federal" military Reserve Components under Title 10 United States Code (i.e., the Army Reserve, Navy Reserve, Air Force Reserve Marine Corps Reserve) or Title 14 United States Code (i.e., Coast Guard Reserve when not operating as part of the U.S. Navy) are subject to the UCMJ if they are either (a) active duty Full-Time Support personnel such as FTS or Active Guard and Reserve (AGR), or (b) "traditional" part-time reservists performing either (a) full-time active duty for a specific period (i.e., Annual Training, Active Duty for Training, Active Duty for Operational Support, Active Duty Special Work, One Year Recall, Three Year Recall, Canvasser Recruiter, Mobilization, etc.), or (b) when they are performing Inactive Duty (i.e., Inactive Duty Training, Inactive Duty Travel and Training, Unit Training Assembly, Additional Training Periods, Additional Flying Training Periods, Reserve Management Periods, etc., all of which are colloquially known as "drills").
National Guard of the United States soldiers and airmen (i.e., Army National Guard and Air National Guard) are also subject to the UCMJ, if and only if, activated in a "Federal" capacity under Title 10 United States Code by presidential executive order. Otherwise, the National Guard of the United States is exempt from the UCMJ. However under Title 32 United States Code, National Guard soldiers are still subject to their respective state codes of military justice if serving in active duty under executive order from their respective state governor.
Because they are considered to be in an active duty status, cadets and midshipmen at the U.S. service academies (i.e., United States Military Academy, United States Naval Academy, United States Air Force Academy and United States Coast Guard Academy are also subject to the UCMJ. However, Reserve Officer Training Corps (ROTC) cadets and midshipmen at colleges and universities (who, unlike Academy cadets and midshipmen, are not considered to be on...