Alexander Campbell King was born on December 7, 1856 in Charleston, South Carolina to J. Gadsden and Caroline Clifford (Postell). At the age of nineteen, King was admitted to the South Carolina Bar although he had not finished college. In 1916, King received a civil law degree from the University of the South, in Sewanee, Tennessee. Following his admittance to the bar, King began a series of jobs serving as general legal counsel to various railroad companies. For the Atlanta & West Point Railroad he took the position of assistant general counsel (1887-1893), simultaneously serving as general counsel for the East & West Railroad of Alabama (1887-1889), and again as assistant general counsel to the Richmond & Danville Railroad and Richmond & West Point Terminal Co., from 1890-1892. Lastly, King represented the Chattanooga, Rome & Columbus Railroad from 1894-1901. In 1912, King was appointed to the U.S. Court of Appeals, 5th Circuit, as a committee member to report on revision in equity in U.S. courts. He also served on the board of directors, and as one term chairman, of the State Bar Examiners from 1913-1918.
In November of 1918, President Wilson appointed King to serve as solicitor general. With his breadth of knowledge in railroad legislation he was a valuable asset to the administration, contributing his expertise when faced with cases involving the Southern Pacific Railroad throughout 1919. During this time he also served as a counselor for the American Red Cross. After his appointment as a judge to the U.S. 5th Circuit in May 1920, King resigned from his position as SG. He served the 5th District from 1920-1925, upon which he resigned to become a partner in the firm of King, Spalding, MacDougal & Sibley, near his home in Atlanta, Georgia. King passed away soon thereafter on July 26, 1926. He was survived by his wife of 45 years, Alice May Fowler, and sons Edward and Alexander C., and laid to rest in Atlanta, Georgia.