He is the son of Pierre Cot, also politician and minister.
After studying law at Sorbonne University in Paris from 1955 to 1965, he earned a Ph.D. in 1966. He then was professor of public law and international law at the University of Amiens, then the University of Paris I, before being elected to the Savoy in 1973. He was later re-elected, before joining the Socialist government of Pierre Mauroy in 1981 as deputy Minister in charge of Co-operation and Development.
Since 2002 he has been a member of the International Tribunal for the Law of the Sea.