After graduating from law school, Cain worked in private legal practice in Walhalla, South Carolina from 1986 until 1988 (including a stint in 1987 as a public defender in Seneca, South Carolina), and then as an assistant county solicitor in Seneca from 1988 until 1989. He then worked as an associate for a Seneca law firm from 1990 until 1991. Cain then worked as a partner in differently comprised firms in Seneca from 1991 until 1993, 1993 until 1996. 1996 until 1998 and 1998 until 2000.[1] During Cain's time in private practice, he worked alongside future United States Senator Lindsey Graham for about three years.[3] Cain also served as county attorney for Oconee County, South Carolina from 1992 until 2000.[1] In 2000, Cain became a family court judge in Columbia, South Carolina.[1][2]
Federal judicial service
On February 16, 2011, President Barack Obama nominated Cain to a seat on the United States District Court for the District of South Carolina that had been vacated by Judge Patrick Michael Duffy who assumed senior status in 2009.[4] The Senate confirmed Cain on September 20, 2011 by a 99–0 vote.[5] He received his commission on September 26, 2011. He became the Chief Judge on June 4, 2024.[2]