He was born in Geoje, South Korea.He was the first son among five children of his parents.His father, Moon Yong-hyung was a refugee from South Hamgyeong Province (presently in North Korea) who settled in Geoje as a laborer.Moons family finally settled in Busan, where he attended the high school.During his studies in Kyunghee University, he was arrested and expelled from the university for organizing a student protest against the Yushin Constitution.Later, he was commissioned in the South Korean Military and became a part of a military mission during the Axe murder incident.He stood 2nd in the Bar Exam. However, he was not allowed to become a judge/government prosecutor as he had been involved in the activities against the dictatorship as a student. So, he chose to become a lawyer instead.As a lawyer, he worked with future President Roh Moo-hyun and became a close friend of him. He remained his friend until Rohs suicide in 2009.He took a number of cases involving civil rights issues and human rights. He became a member of Minbyun and later, served as the Chairman of Human Rights at Busan Bar.In 1988, he became a founding member of the South Korean newspaper The Hankyoreh..