He was in the United States Air Force from 1964 to 1967, and then in private practice in Cheyenne from 1968 to 1971.
Johnson was then a United States magistrate judge for the District of Wyoming from 1971 to 1974.
Johnson was a substitute judge of the Municipal Court of Cheyenne, Wyoming from 1973 to 1974, and a judge on the Wyoming state district court from 1974 to 1985.
[1] On October 22, 1985, Johnson was nominated by President Ronald Reagan to a new seat on the United States District Court for the District of Wyoming created by 98 Stat.
[1] Johnson's official portrait was painted by artist Michele Rushworth and was unveiled and installed in the federal courthouse in Cheyenne, Wyoming in 2012.