The Constitution of the Kingdom of Thailand provides the basis for the rule of law in Thailand. Since the abolition of the absolute monarchy in 1932, Thailand has had 20 charters or constitutions, an average of one roughly every four years. Many changes followed military coups, reflecting the high degree of political instability in the country. After each successful coup, military regimes abrogated the existing constitution, generally without public consultation.

Thailand, officially the Kingdom of Thailand and historically known as Siam, is a country in Southeast Asia on the Indochinese Peninsula. With a population of almost 70 million, it spans 513,120 square kilometres (198,120 sq mi). Thailand is bordered to the northwest by Myanmar, to the northeast and east by Laos, to the southeast by Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the southwest by the Andaman Sea; it also shares maritime borders with Vietnam to the southeast and Indonesia and India to the southwest. Bangkok is the state capital and largest city.