[1] He served as a law clerk for Justice William J. Brennan Jr. of the Supreme Court of the United States from 1960 to 1961.

[1] He was legislative assistant to United States Senator Dale Bumpers from 1975 to 1978.

His service terminated on March 7, 1980, due to his elevation to the Eighth Circuit.

[1] Arnold was nominated by President Carter on December 19, 1979, to the United States Court of Appeals for the Eighth Circuit, to a new seat authorized by 92 Stat.

He served as Chief Judge and as member of the Judicial Conference of the United States from 1992 to 1998.