DEFINITION & ETYMOLOGY
Martial law (戒厳令 / 계엄령) is the imposition of direct military control over normal civil functions of government. The term derives from the Japanese kaigenrei, combining 戒 (caution), 厳 (strict), and 令 (decree/order) — literally, a "strict caution decree."
Under martial law, the military commander of an area or country assumes absolute authority. Civil liberties are suspended, habeas corpus is set aside, and the civilian judicial system is replaced by military tribunals. The decree transforms the relationship between state and citizen from one of negotiated rights to one of commanded compliance.
The legal basis for martial law varies by jurisdiction. In some constitutions, the power is explicitly granted; in others, it exists as an implicit executive prerogative. The ambiguity itself is the mechanism — when the rules for suspending rules are unclear, authority defaults to whoever commands the most force.