Arnold was nominated by President George H. W. Bush on November 6, 1991, to a seat on the United States Court of Appeals for the Eighth Circuit vacated by Judge Donald P. Lay. He was confirmed by the Senate on May 21, 1992, and received his commission on May 26, 1992. He assumed senior status on October 9, 2006. He served as a Judge of the United States Foreign Intelligence Surveillance Court of Review from 2008 to 2013, serving as Presiding Judge from 2012 to 2013.
