He was admitted to the North Dakota Bar in 1934, and later spent a two-year period as a special agent for the
FBI. He practiced law in
Devils Lake, North Dakota until 1954. He also served as
Ramsey County State's Attorney from 1937 to 1943 and from 1945 to 1946. He served as District Judge for the Second Judicial District from 1954 to 1958. On December 31, 1958, he was appointed to the Supreme Court to replace Justice
Gudmunder Grimson, (1878–1965). He assumed office on January 13, 1959, at the age of 50. He was elected to a ten-year term in 1960 and reelected in 1970. He resigned in July 1974 and was succeeded by
J. Philip Johnson. Following his retirement from the Court, Justice Teigen accepted an appointment as an Administrative Judge with the
Social Security Administration in 1975, but he developed a terminal illness in the late-1970s, which forced his resignation in February 1978. ==Personal life==