Career
Because of his Calvinist background Kooijmans felt themselves politically most at home in the ARP and he held various positions within the party. When this party merged into the CDA Kooijmans remained politically active, both in the Netherlands and at European level.
Kooijmans' career of the jurist largely takes place within the academic world. He was Professor of International Law and European Law at the Free University and at the University of Leiden. In 1973 he was Minister of Foreign Affairs. From 6 February 1997 to February 2005 Kooijmans was a Judge at the International Court of Justice.
On 13 July 2007 he was appointed Minister of State.