The United States Constitution grants to Congress the power to raise and support armies and a navy, to suppress insurrections, and repel invasion among other military-related governmental roles. The main source of legal authority in this area is federal law. Congress's control over formation, organization and government of the national armies is plenary and exclusive.
Military law consists
of the Uniform Code
of Military Justice
and other statutory
provisions for the government
of persons in the Armed
Forces to which may
be added the unwritten
common law of the usage
and custom of military
service and regulations.
President as Commander
in Chief of the Armed
Forces.
It is a part of our
body of law as a whole,
and is fully recognized
by civil courts; it
is in force in time
of peace as well as
in time of war. All
persons serving in the
Armed Forces of the
United States are subject
to military law at all
times.