| Sanya Dharmasakti | |
| Native Name Lang: | th |
| Honorific-Suffix: | MPCh MWM PCh NR GCS |
| Office1: | President of the Privy Council |
| Monarch1: | Bhumibol Adulyadej |
| Term Start1: | 5 December 1975 |
| Term End1: | 4 September 1998 |
| Predecessor1: | Dej Snidvongs |
| Successor1: | Prem Tinsulanonda |
| Office2: | 12th Prime Minister of Thailand |
| Monarch2: | Bhumibol Adulyadej |
| Term Start2: | 14 October 1973 |
| Term End2: | 26 February 1975 |
| Predecessor2: | Thanom Kittikachorn |
| Successor2: | Seni Pramoj |
| Office3: | Rector of Thammasat University |
| Term Start3: | 1 April 1971 |
| Term End3: | 16 October 1973 |
| Predecessor3: | Prince Wan Waithayakon |
| Successor3: | Adul Wichiencharoen (acting) |
| Office4: | President of the Supreme Court |
| Monarch4: | Bhumibol Adulyadej |
| Term Start4: | 1 October 1963 |
| Term End4: | 1 October 1967 |
| Predecessor4: | Prawat Pattabongse |
| Successor4: | Prakob Hutasingh |
| Birth Name: | Sanya |
| Birth Date: | 5 April 1907 |
| Birth Place: | Thonburi, Krung Thep, Siam (now Bangkok Yai, Bangkok, Thailand) |
| Death Place: | Ramathibodi Hospital, Ratchathewi, Bangkok, Thailand |
| Profession: | Lawyer |
| Signature: | Sanya Thammasak signature.svg |
Sanya Dharmasakti (Thai: สัญญา ธรรมศักดิ์,, in Thai pronounced as /sǎn.jāː tʰām.mā.sàk/; 5 April 1907 – 6 January 2002) was a Thai jurist, university professor and politician. He served as the 12th Prime Minister of Thailand from 1973 to 1975.
Sanya Dharmasakti was one of the most influential figures in the politics of Thailand. He served as the president of the Supreme Court (1968–1973) and was dean of the faculty of law and chancellor of Thammasat University during the democracy movement of October 1973. When the "three tyrants" fled, leaving the country leaderless, Sanya was appointed prime minister by royal command (establishing a precedent exercised only three times since for appointment of prime ministers.) Sanya served a second consecutive term by a House resolution for a combined total of 1 year, 124 days, during which he ordered the withdrawal of US forces in what was called Operation Palace Lightning. Sanya appointed a drafting committee for the 1974 constitution, served as vice-president of the constitutional congress, and was requested by the monarch to serve as the president of the privy council.
Dharmasakti was born on Friday, 5 April 1907 in Thonburi Province, in central Thailand. His father was the high ranking Buddhist scholar, Mahamtree, and abbot, Dhammasarnvetvisetpakdee Srisattayawatta Phiriyapaha or Thongdee Dharmasakti. His mother was Shuen Dharmmasarnvet. Sanya married Pa-nga Dharmasakti, also known as Phenchart, who died in 2001. They had two sons, named Chartsak and Jakatham.
Dharmasakti went to Assumption College in 1914 and finished high school, majoring in English in 1925. He went to the law school of the Ministry of Justice for three years, graduating in 1928. He got the highest score and received the Rapheeboonnithi scholarship. This scholarship allowed him to study law in England at the Middle Temple for three years. He was called to the English Bar in 1932.
Palace Lightning was the name given the plan by which the USAF withdrew its aircraft and personnel from Thailand. After the fall of the US-supported governments in both Phnom Penh and Saigon in the spring of 1975, the political climate between Washington and the government of Judge Sanya soured, and US military forces were ordered to withdraw by the end of the year.[1] Strategic Air Command units left in December 1975;[2] U-Tapao Royal Thai Navy Airfield, however, remained under US control until formally handed back to the Thai government on 13 June 1976.[3]
Sanya Dharmasakti died at Ramathibodi Hospital, Bangkok on 6 January 2002.
Sanya received the following royal decorations in the Honours System of Thailand:
Japan : 
Germany : 
Philippines : 
Peru :