Tan Boon Teik SC DUBC (/ˌtɑːn ˌbʊn ˈteɪk/ tahn-buun-TAYK;[2] 17 January 1929 – 10 March 2012) was a Singaporean judge who served as the second attorney-general of Singapore between 1969 and 1992.

Tan attended University College London before he was called to the Bar in 1952 as a barrister-at-law of England and Wales by Middle Temple, and became an advocate and solicitor of the Supreme Court of the Federation of Malaya in 1954.

He was subsequently appointed Deputy Registrar and Sheriff of the High Court in 1956, Director of the Legal Aid Bureau in 1959, and Senior Crown Counsel in 1963.

During his tenure, he prepared many legal opinions on important constitutional and administrative law issues, and was also the Government's lead counsel in a number of notable cases.

[10] In 1961, he represented Singapore at the Seminar on the Protection of Human Rights in the Administration of Criminal Justice organised by the United Nations in Wellington, New Zealand.

He was also the Government's lead counsel in a number of notable cases,[8] including Lee Mau Seng v. Minister for Home Affairs (1971),[13] which involved four executives of the Nanyang Siang Pau (South Seas Business Newspaper), a Chinese-language newspaper, who had been detained without trial under the Internal Security Act ("ISA")[14] for "glamorising communism and stirring up communal and chauvinistic sentiments over Chinese language, education and culture".

[16] Although the judgment was later disapproved by the Court of Appeal in Chng Suan Tze v. Minister for Home Affairs (1988),[17] in 1989 Parliament amended the Constitution and the ISA to "freeze" the law relating to detentions under the Act to that applying in Singapore on the date when Lee Mau Seng was decided.

[8] Under Tan's leadership of the Attorney-General's Chambers, Gemini's managing director Abdul Gaffar Mohamed Ibrahim pleaded guilty to criminal breach of trust of $3.2 million and was sentenced to life imprisonment,[21] and its chairman V.K.S.

[23] Tan also successfully brought proceedings for scandalising the court against Wong Hong Toy, the Chairman of the Workers' Party of Singapore, in 1983,[24] and against respondents involved in publishing, printing and distributing articles that appeared in the Asian Wall Street Journal in 1985[25] and 1991.

[29] In January 1990, the Attorney-General's Chambers launched LawNet, a computer database then containing the full text of Singapore legislation, at the cost of $4.3 million.

[1][8] Tan was appointed the Chairman of the Singapore International Arbitration Centre (SIAC) when it was formed in July 1991,[31] and held the post until August 1999.

[38] In September that year he was named Ambassador to Hungary resident in Singapore,[39] and in January and May 1994 the non-resident ambassadorships of Austria and the Slovak Republic were respectively added to his portfolio.

[4][43][44] In July 1992, Tan was appointed a director of United Industrial Corporation Ltd. (UIC) and its property arm, Singapore Land Ltd.[45] He became Chairman of Morgan Grenfell Asia Ltd. in November 1993.

The Attorney-General's Chambers itself released a statement saying that Tan had held office "during a crucial period in Singapore's history in the years after independence.