S Jayakumar was born on 12 August 1939.
He was educated at Raffles Institution. He studied law at the University of Singapore, where he graduated with a Bachelor of Law (Honours) degree in 1963. He was admitted to the Bar in 1964. He furthered his education at the Yale Law School, US, where he received his Master of Law in 1966.
He taught at the Faculty of Law in the National University of Singapore (formerly known as the University of Singapore) from 1964 to 1981. He became the Dean of the Law Faculty in 1974.
During his career at the university, Prof Jayakumar wrote 3 books and 32 articles on constitutional law, international law and legal education.
In 1971, he was seconded to the Ministry of Foreign Affairs to serve as Singapore's Permanent Representative to the United Nations (UN) and High Commissioner to Canada. He served in this capacity until 1974. From 1974 to 1979, he was a member of Singapore's delegation to the UN Law of the Sea Conference.
In 1980, he was elected the Member of Parliament (MP) for Bedok Constituency. He was re-elected the MP for Bedok in 1984. Under the Group Representation Constituency (GRC) scheme, he was elected as one of the three MPs in the same GRC in 1988. He was re-elected as one of the four MPs in the same GRC in the 1991 General Election. He was re-elected as one of six MPs for the East Coast GRC in the 1997 GE. In 2006, he was re-elected in the new five-member East Coast GRC.
He was appointed Minister of State for Law and Minister of State for Home Affairs in 1981. He was appointed Minister for Labour, Second Minister for Home Affairs and Second Minister for Law in 1984.
In 1985, Prof Jayakumar was appointed Minister for Home Affairs and Second Minister for Law. In 1988, he was appointed Minister for Law and Minister for Home Affairs.
In November 1990, he was re-appointed Minister for Law and Minister for Home Affairs in the Government led by Prime Minister Goh Chok Tong. He was re-appointed to these posts in September 1991.
On 2 January 1994, he relinquished his appointment as Minister for Home Affairs. He was appointed Minister for Foreign Affairs while retaining his portfolio in Law. On 25 January 1997 he was re-appointed Minister for Law and Minister for Foreign Affairs. After the General Election in 2001, he was re-appointed to the same portfolios on 23 November 2001.
On 12 August 2004, he was appointed Deputy Prime Minister and Minister for Law and he relinquished his appointment as Minister for Foreign Affairs.
On 1 September 2005, he was appointed Co-ordinating Minister for National Security.
On 30 May 2006, he was re-appointed Deputy Prime Minister, Co-ordinating Minister for National Security and Minister for Law by Prime Minister Lee Hsien Loong.
On 1 May 2008, he relinquished his appointment as Minister for Law.
He was awarded the Public Service Star (BBM) in 1980. He is married to medical doctor, Dr. Lalitha Rajahram. They have two sons and a daughter.
Prof Jayakumar enjoys jogging, golfing and in-line skating.