Born in Brigham City, Utah, Jensen received an Artium Baccalaureus degree from the University of California, Berkeley in 1949 and a Bachelor of Laws from the UC Berkeley School of Law in 1952.

[1] Jensen was a deputy district attorney of Alameda County, California, from 1955 to 1966.

Jensen received a LEAA grant to develop DALITE (District Attorney's Automated Legal Information System),[2] a case management software program, like PROMIS (Prosecutor's Management Information System), developed by Inslaw.

[4] He was the Assistant Attorney General of the Criminal Division of the United States Department of Justice from 1981 to 1983.

Jensen was nominated by President Ronald Reagan on June 2, 1986, to a seat on the United States District Court for the Northern District of California vacated by Judge William H. Orrick Jr.