Served on the Iowa Supreme Court from April 17, 1962, when he was appointed to fill the vacancy occasioned by the retirement of Justice William L. Bliss, until his retirement August 2, 1978, at age 75. From 1969 to 1978 he was Chief Justice. He served as a Senior Judge, 1979-1987. His judicial career spanned over 50 years - longer than any justice in Iowa history - and included service on every level of the judiciary.
He was the second native of Des Moines, Iowa's capital city, to serve on the Supreme Court. After graduating from Drake Law School in 1927 he engaged in private practice in Des Moines until he became an Assistant County Attorney of Polk County in 1934. He remained with the office until April 1, 1936. From 1936 to 1943 he served as a Des Moines Municipal Court Judge. Later he was elected to five successive four-year terms in the then Ninth Judicial District [1943-1962].
Chief Justice Moore gave lectures on numerous legal subjects at the Drake Law School from 1942 to 1962. After his retirement from the court, Chief Justice Moore continued to reside in Des Moines in Lee Township until his death May 11, 1988.