 12 years after being appointed Reporter of Decisions, Appleton was appointed by Governor John Hubbard on May 11, 1852 to serve on the Maine Supreme Judicial Court as an Associate Justice to fill one of the seats created by Appleton's own recommendation to the legislature.Appleton received national recognition at the time for his efforts to reform rules of evidence.Appleton was an opponent of the prevailing legal philosophy of the time that assumed juries could not rationally discern between reliable and unreliable testimony and evidence.