La Rue was born in Guatemala. Born legally blind, he nevertheless enrolled in and graduated from the Universidad de San Carlos de Guatemala with a law degree. La Rue served as legal adviser to the Central General de Trabajadores de Guatemala, the country's largest labor federation, from 1975 to 1980, during which time he had occasion to defend numerous labor union personnel and clergymen amid the country's worsening Civil War. He was consequently marked for death, and in 1981 he and his family sought exile in the United States. He served until 1989 as attorney and political analyst for numerous Guatemalan political exiles, including Rigoberta Menchú (1992 Nobel Peace Prize laureate), and in 1990 co-founded the Center for Legal Action for Human Rights (CALDH). LaRue obtained a postgraduate degree in U.S. foreign policy from Johns Hopkins University in 1985.