Martial law is the replacement of civilian government by military rule and the suspension of civilian legal processes for military powers. Martial law can continue for a specified amount of time, or indefinitely, and standard civil liberties may be suspended for as long as martial law continues. Most often, martial law is declared in times of war and/or emergencies such as civil unrest and natural disasters. Alternatively, martial law may be declared in instances of military coup d'états.

The 2006 Thai coup d'état took place on 19 September 2006, when the Royal Thai Army staged a coup d'état against the elected caretaker government of Prime Minister Thaksin Shinawatra. The coup d'état, which was Thailand's first non-constitutional change of government in fifteen years since the 1991 Thai coup d'état, followed a year-long political crisis involving Thaksin, his allies, and political opponents and occurred less than a month before nationwide House elections were scheduled to be held. It has been widely reported in Thailand and elsewhere that General Prem Tinsulanonda, a key person in the military-monarchy nexus, Chairman of the Privy Council, was the mastermind of the coup. The military cancelled the scheduled 15 October elections, abrogated the 1997 constitution, dissolved parliament and the constitutional court, banned protests and all political activities, suppressed and censored the media, declared martial law nationwide, and arrested cabinet members.