Born in St. Joseph, Missouri, Fenner received a Bachelor of Arts degree from the University of Kansas in Lawrence, Kansas in 1970 and a Juris Doctor from the University of Missouri-Kansas City School of Law in 1973.

Fenner was nominated by President Bill Clinton on December 13, 1995, to be a United States District Judge of the United States District Court for the Western District of Missouri, to a seat vacated by Scott Olin Wright.

In May 2024, NPR revealed that Fenner had received free travel in December 2021 to the Breakers Colloquium, a privately funded legal seminar hosted at The Breakers resort in Palm Beach, Florida, but had failed to disclose this on his required annual financial disclosure report for that year, in violation of federal law.

[2] In response, Fenner told NPR, "I’m embarrassed about the fact that somehow that was overlooked by me.

"[2] This biography of a federal judge in the United States is a stub.