He was staff attorney of the Office of Temporary Controls, in Sioux Falls, South Dakota, in 1946.
He was also staff attorney of the Office of Temporary Controls, in Saint Paul, Minnesota, in 1947.
In 1976, Porter was appointed by Governor Richard F. Kneip to a seat as an associate justice of the South Dakota Supreme Court, serving from 1977 to 1979.
While he remained a federal judge, he no longer heard cases or participated in the business of the court.
[1][3] Among the judicial law clerks that served Porter was Roberto Lange, also a United States district judge.