Dallas Clark graduated from Wake Forest University with a BA and JD. During law school, he enlisted in the US Marines, earned his commission, completed officer combat infantry training and was certified as a military lawyer. He volunteered to serve in Vietnam and was posted with the Third Marine Division where he was assigned as defense counsel, trial counsel and chief trial counsel for the 20,000-man Division.

Shortly after reporting for duty as a legal officer, he was approached by two officers who had successfully prosecuted a Marine charged with crimes relating to the murder of a lieutenant by fragging. The prosecuting officers informed Lieutenant Clark they had begun to believe, after the conviction, the Marine may have been innocent.