He served in the United States Army from 1967 to 1969, attaining the rank of captain. He was a public school teacher in El Paso and a legislative aid in both houses of the Texas Legislature. He was admitted to the bar and was an assistant county attorney in El Paso County from 1969 to 1973. He attended the University of Kent in 1981.
He was elected as a to the 98th United States Congress and to the six succeeding Congresses. serving from 1983 to 1997. He was not a candidate for re-election to the 105th United States Congress. In 1992, it was revealed that Coleman had over 670 overdrafts as part of the House banking scandal but was still able to win re-election.[1] In Congress he was a member of the House Appropriations Committee, the House Armed Services Committee, and the Select Committee on Intelligence.