 De Brichambaut joined the Council of State, France's supreme court for judicial review, in 1974.In 1983 and 1984, de Brichambaut was chief of staff to Roland Dumas, then Minister of European Affairs, and after Dumas became Minister of Foreign Affairs, de Brichambaut continued to serve as his chief of staff.In 1986, he moved to Washington, D.C., where he worked as cultural Counsellor for the French Embassy, returning to Paris in 1988 as Principal Adviser to Defense Minister Jean-Pierre Chevenement.