John M. Hemphill was the son of Paul and Bessie McLure Hemphill. He was educated in the Chester public schools and received an A.B. from the University of South Carolina in 1908. He was a member of the Kappa Alpha social fraternity.
In 1910, he was admitted to the Bar after having studied law in the offices of his father and grandfather. He served in the South Carolina General Assembly as a State Representative from Chester County from 1916 to 1917. He was appointed as a Special Circuit Judge for South Carolina Judicial Circuits often between 1928 and 1945.
He served as Grand Chancellor of the South Carolina Grand Lodge, Knights of Pythias from 1924 to 1925. He was a Mason and a Shriner, as well as a member of the York J.O.U.A.M. Presbyterian Church.
In 1913, he married Helen Witherspoon of York and they had three children, Robert Witherspoon, John McLure, Jr. (who died in the armed service in 1942), and Helen H. Wooldridge. For relaxation, he fished and swam.
A prodigious worker, tenacious and persistent in representing his clients, his infinite capacity for detail and his thorough preparation of cases enabled him to enjoy a good courtroom fight, and made him an able trial lawyer.
With vigor and honor, he maintained his family’s tradition of serving the cause of justice.