[carguychris]

I should have posted this too. It's out of the Definitions section, 27 CFR (Code of Federal Regulations) § 478.11, and it makes things even more clear:

Adjudicated as a mental defective. (a) A determination by a court, board, commission, or other lawful authority that a person, as a result of marked subnormal intelligence, or mental illness, incompetency, condition, or disease:
(1) Is a danger to himself or to others; or
(2) Lacks the mental capacity to contract or manage his own affairs.
(b) The term shall include--
(1) A finding of insanity by a court in a criminal case; and
(2) Those persons found incompetent to stand trial or found not guilty by reason of lack of mental responsibility pursuant to articles 50a and 72b of the Uniform Code of Military Justice, 10 U.S.C. 850a, 876b.

Committed to a mental institution. A formal commitment of a person to a mental institution by a court, board, commission, or other lawful authority. The term includes a commitment to a mental institution involuntarily. The term includes commitment for mental defectiveness or mental illness. It also includes commitments for other reasons, such as for drug use. The term does not include a person in a mental institution for observation or a voluntary admission to a mental institution.

Note the sections I underlined. There you have it, straight from the horse's mouth.