Van Agt a jurist by occupation, worked as a lawyer for the law firm Van der Putt, Nijst, Van Sandick en Depla from 1956 until 1958 when he became a civil servant working for the Ministry of Agriculture and Fisheries and the Ministry of Justice until 1968. Van Agt became a professor of criminal procedure at the Radboud University Nijmegen in 1968. In 1971 he was appointed as a judge at the court of Arnhem. After the Dutch general election of 1971 Van Agt was asked by the Catholic People's Party (KVP) to become Minister of Justice in the first Biesheuvel cabinet. Van Agt accepted and resigned as a professor and judge the same day he took office as the new Minister of Justice on 6 July 1971. Van Agt remained Minister of Justice in the Den Uyl cabinet following the Dutch general election of 1972 and also became Deputy Prime Minister on 11 May 1973. On 10 December 1976 Van Agt was selected as the first Leader of the Christian Democratic Appeal and became the lijsttrekker (top candidate) for the Dutch general election of 1977. He resigned as Deputy Prime Minister and Minister of Justice to become the first Parliamentary leader of the Christian Democratic Appeal in the House of Representatives and a Member of the House of Representatives taking office on 8 June 1977. Following the election the Christian Democratic Appeal became the second largest party in the House of Representatives.
After a failed cabinet formation with the Labour Party, Van Agt struck a deal with the Leader of the People's Party for Freedom and Democracy Hans Wiegel that resulted in the formation of the Van Agt-Wiegel cabinet with Van Agt becoming Prime Minister of the Netherlands taking office on 19 December 1977. With the following Dutch general election of 1981, Van Agt again as lijsttrekker lost one seat and a coalition formation with the Labour Party and the Democrats 66 (D66) resulted in the second Van Agt cabinet. On 29 May 1982 the second Van Agt cabinet collapsed after the Labour Party retracted their support. A rump cabinet Van Agt III was formed with Van Agt also serving as Minister of Foreign Affairs. The third Van Agt cabinet stayed in office until the Dutch general election of 1982. Van Agt again as lijsttrekker lost three seats and the Christian Democratic Appeal became the second largest party. A cabinet formation with the People's Party for Freedom and Democracy (VVD) was formed but Van Agt unexpectedly announced his retirement from national politics and stood down as Leader of the Christian Democratic Appeal on 25 October 1982. Van Agt remained Prime Minister of the Netherlands until the first Lubbers cabinet was installed on 4 November 1982.
After his premiership, Van Agt remained in active politics and became the Queen's Commissioner of North Brabant taking office on 1 June 1983. On 22 April 1987 Van Agt resigned as Queen's Commissioner because of criticism on his cooperation with the States-Provincial. Van Agt he became a diplomat for the European Communities and served as Ambassador of the European Union to Japan from 1 April 1987 until 1 January 1990 when he became Ambassador of the European Union to the United States serving until 1 April 1995 when he retired from politics at the age of sixty-four. Following the end of his active political career, Van Agt occupied numerous seats on supervisory boards on international non-governmental organizations (InterAction Council, Green Cross International and the Edmund Burke Foundation). Van Agt served as a visiting professor of international relations at the Ritsumeikan University, the United Nations University and the Kwansei Gakuin University from 1995 until 2004.
Van Agt is known for his abilities as a negotiator and debater. During his premiership, his cabinets were responsible for reforming the public sector and civil service and the struggle with the recession in the 1980s. He holds the distinction of being the first Christian Democratic Appeal Prime Minister of the Netherlands. Van Agt also has been active as an anti-war and human rights activist and as an advocate in promoting the Two-state solution for the Israeli–Palestinian conflict. Van Agt continues to comment on political affairs as a statesman. With the death of Piet de Jong in July 2016, he became the oldest living former Dutch Prime Minister.
Andreas Antonius Maria van Agt was born on 2 February 1931 in Geldrop in the Netherlands Province of North Brabant in a Roman Catholic family. After receiving his diploma Gymnasium-A at the Augustinianum he studied at the Catholic University of Nijmegen, where he received his Doctorate in Law in 1955. After graduating, he practiced law in Eindhoven until 1957, after which he worked in the office of legal and business affairs of the Ministry of Agriculture and Fisheries until 1962. From 1962 to 1968, he worked for the Ministry of Justice.
Van Agt entered politics as a member of the Catholic People's Party, which merged with the other two major Christian Democratic parties in 1980 to form the Christian Democratic Appeal (CDA). From 1968 to 1971, Van Agt was Professor of Criminal Law at the Catholic University of Nijmegen. From 1971 to 1973, he was Minister of Justice in the government of Barend Biesheuvel. He caused outrage when he tried to pardon the last three Nazi war criminals still in Dutch prisons in 1972. From 1973 to 1977 he was Deputy Prime Minister and Minister of Justice in the government of Joop den Uyl.
In 1976, Van Agt was elected the first Leader of the Christian Democratic Appeal, then still a federation of the three religious parties Christian Historical Union, Catholic People's Party and Anti-Revolutionary Party, which first ran in 1977 with a united list (the merger followed in 1980). With Van Agt as top candidate, the Christian Democratic Appeal reversed in 1977 years of decline to return to power.