Joseph Holt was born in Breckinridge County, Kentucky, on January 6, 1807. From 1828 until his retirement in 1842, Holt practiced law in Kentucky and Mississippi. After he retired as an attorney, Holt moved to Louisville and became active in Democratic politics. In 1857, President James Buchanan appointed Holt commissioner of patents. Holt then became postmaster general in 1859 and secretary of war in 1860. When the Civil War broke out in April 1861, Holt worked to prevent secession in Kentucky and was crucial in strengthening Unionist sentiment in the state. In 1862, President Abraham Lincoln appointed Holt judge advocate general, where he served until 1864, when he was made head of the Bureau of Military Justice. In that office, he oversaw the trial of the Lincoln assassins. In 1875, he resigned from that position and lived in Washington until his death on August 1, 1894.

James D. Bennett, "Joseph Holt," in The Kentucky Encyclopedia, ed. John E. Kleber (Lexington: University Press of Kentucky, 1992), 438.