A member of the bar, he founded his own law firm in 1968 and served as legal adviser to the Ministry of Planning and Economic Affairs during his uncle's administration. Tubman has extensive United Nations experience. His first job was in the Legal Office in 1973. He served under Samuel Doe as Justice Minister from 1982 to 1983. Tubman traveled to the United Sates in 1990 on behalf of Doe to unsuccessfully lobby the American government to intervene in the First Liberian Civil War. He more recently served as the Secretary-General's representative and head of the United Nations Political Office for Somalia from 2002 to 2005.