That year Simpson resigned to become Chief Justice of the South Carolina Supreme Court.

He practiced law in Laurens with his partner (and father-in-law) Henry Clinton Young.

[1] He served in the South Carolina legislature in the 1850s and early 1860s, and in the Confederate States House of Representatives from 1863 to 1865.

[2][3][4] After the Civil War, Simpson returned to practice law in Laurens until 1876, when he ran successfully for the post of lieutenant governor.

Upon Wade Hampton resigning from the governorship to assume his US Senate seat (to which he was elected by the state legislature), Simpson was elevated to become the 78th governor of South Carolina.