He was a deputy prosecuting attorney of St. Joseph County, Indiana in 1935 and 1936, returning to private practice until 1938.

He was an unsuccessful candidate for reelection to the Eighty-first Congress in 1948, and resumed the practice of law in South Bend.

He served as Chief Judge from 1961 to 1972 and as a member of the Judicial Conference of the United States from 1969 to 1972, assuming senior status on December 1, 1972.

In 1976, he was appointed by Chief Justice Warren E. Burger to the United States Temporary Emergency Court of Appeals, serving until 1993.

Grant continued to serve in senior status until his death on March 2, 1998, in Sarasota, Florida.