Born in Winnsboro, Thomas McDonald was the son of attorney James Edwin McDonald and Lillie M. Elliott. In World War I, he attended the Officer’s Training School in Plattsburg, New York. After the war, he received an A.B. from Erskine College in 1919, and an LL.B. from the University of South Carolina in 1921. He practiced law in Winnsboro and became dean of its Bar.
He was married to Mary Camilla Davis of Summerton and they had a daughter and three sons, one of whom practiced with him in the firm of McDonald and McDonald. He served as an Elder in the Associate Reformed Presbyterian Church, as President of the Rotary Club, as a member of the Fairfield Country Club and Director of the Community Federal Savings and Loan Association.
Like his father, he served as Chairman of the Fairfield Democratic Committee from 1928 until 1950. He also served on the South Carolina Board of Corrections and on the first Board of Commissioners on Grievances and Discipline created by the South Carolina Supreme Court. He was often appointed as a Special Circuit Judge.
He was a charter member of the National Association of Railway Trial Council and a member of the South Carolina and American Bar Associations. During World War II, he served on the County Selective Service Board and as a Government Appeal Agent. A gracious gentleman. In representing clients, he was patient, thorough, and tenacious. An able trial lawyer.