[1] He subsequently taught school and then began the study of law under Governor Aaron V. Brown and James K. Polk, who were then partners.
In 1831 he moved to Florence, Alabama, and became associated with John McKinley, who later became a justice of the United States Supreme Court.
On the resignation of Chief Justice William L. Sharkey, Governor James Whitfield appointed Tarpley to the supreme bench.
He drafted its charter, was one of its directors, devoted much time to the enterprise, and lived to see the fruition of the project which was regarded by many "as the dream of a visionary".
He was an ardent Democrat, was a member of the Baltimore convention of 1852, and earnestly advocated the election of Jefferson Davis as governor of Mississippi.