John A. Hunter was born on November 15, 1833, in Manchester, Ohio, to Hocking H. Hunter and Anne Matlock. His father Hocking H. Hunter was a prominent lawyer in Lancaster, Ohio, and his grandfather Joseph Hunter was the first white settler in Fairfield County. His boyhood friend was Charles Ewing, whose father Thomas Ewing, Sr., was also an eminent lawyer and Whig politician in Lancaster. The two children often played together and pulled pranks on the town’s older boys. In 1857, Hunter enrolled at the University of Virginia with his friend “Charley” in order to study law. For unknown reasons, however, they were granted a leave of withdrawal from the university on March 25, 1858. 

Hunter entered into a law practice with his father in Lancaster in 1860. Just prior to the outbreak of war, he and Ewing moved to St. Louis, Missouri, where they opened their own law practice and lived with Ewing’s brother-in-law William T. Sherman. Hunter and Ewing were with Sherman during the “Camp Jackson affair,” when a deadly riot broke out after Union forces captured a unit of secessionists outside the city. All three men survived, and they soon joined the Union army.

Hunter was mustered into the 13th Ohio Infantry Regiment as a lieutenant. He was soon promoted by the Governor of Ohio to captain and served as an aide-de-camp "by virtue of the laws of Ohio" in the 3rd Ohio Infantry Brigade. Hunter served alongside Charles's brother, Hugh Boyle Ewing, under Generals George McClellan and William S. Rosecrans in West Virginia. He turned down the opportunity to join General William S. Rosecrans's staff while Old Rosy was serving in West Virginia. By August 30, 1861, he had mustered out in Columbus, Ohio. He briefly contemplated rejoining the army, filing an application for a paymaster position in December 1862. By the time his application was successful and he was appointed a major and paymaster in Washington, D.C., the following year, he had to decline as he had already "entered into [other] business." He tried once more in the fall of 1864 for a paymaster position, appealing directly to President Abraham Lincoln and citing his efforts on the National Union party's behalf at his local nominating convention, but his application was unsuccessful.

He was an active member of the Lancaster Union party following his service. He appeared on the party's ticket as Prosecuting Attorney of Hocking Township in 1862. He and his father were appointed as delegates to the Union party convention in 1866. Sometime before 1862, Hunter married Mary Duncan, a deeply religious woman. Mary gave birth to their daughter, Ellen Duncan Hunter, known as Nellie, on November 5, 1862, in Lancaster. Mary died of a sudden illness on March 10, 1868.

After his service in the army ended, Hunter became an internal revenue collector for four years. Hunter then briefly returned to St. Louis, forming a law partnership with a Joseph Noble that lasted from 1869 to 1872. He spent a year in England, seeking support for an iron mine in Missouri. At some point, Hunter suffered financial trouble, but Noble insisted it was “rather a misfortune than a fault.” He received an appointment to Chief Justice of the Supreme Court of Utah on July 2, 1879, and held the position until 1884. Hunter faced considerable backlash from the people of Utah for many of his judicial rulings, especially in cases dealing with polygamy, a practice of the Mormon Church. One critic accused, "in the judicial history of America there has seldom been seen such a glaring exhibition of moral cowardice on the part of judges as that which the people of Utah are compelled to witness in the three Justices of the Supreme Court of the Territory.” Fellow UVA Unionist Jacob S. Boreman also served as an Associate Justice on the court from 1873 to 1880, meaning the two judges served on the bench together for one year.

On November 10, 1881, Hunter married Mary Gilbertson, who was over two decade his junior. Mary gave birth to their son, John A. Hunter, Jr., born around 1884. Hunter died after a years-long struggle with diabetes on June 22, 1887, in Salt Lake City. One obituary recalled, "in his capacity as Judge, he made many friends and many enemies.” He was buried with Masonic rites after an Episcopalian funeral. He died intestate, leaving Mary to struggle through lengthy court proceeding in order to settle his affairs. Nellie, by then married to an Englishman and living in Iowa, waived all claims to her father's estate in favor of her brother.

Document:

John A. Hunter to General Rosecrans, December 12, 1861

Memoirs of General William T. Sherman