Served as Chief Justice of the Iowa Territorial Supreme Court from 1838 and as the first Chief Justice of the State Supreme Court until he resigned in June 1847.
Born October 24, 1804, in Onondaga County, New York. He was graduated from West Point Military Academy in 1829 at the head of his class which included Robert E. Lee, Jefferson Davis, and Joseph E. Johnston. For two years he remained at the Academy as Professor of Civil Engineering, later being admitted to the bar in New York.
He wrote the first opinion of the Supreme Court in 1839 while Iowa was a territory. This was the case of the ex-slave Ralph in which it was held that a slave brought into the free territory of Iowa became a free man. This was preliminary and contrary to the famous Dred Scott Decision of the United States Supreme Court.
Justice Mason was a member of the Code Commission of 1851 and represented Iowa in the Missouri boundary dispute. He later became United States Commissioner of Patents and a director of the Smithsonian Institution and of the Naval Observatory. He instituted the system which later became the United States Weather Bureau.
Justice Mason died in Burlington February 22, 1882.