While in law school, Fenner was a member and an editor of the Tulane Maritime Law Journal and authored an article published in the Journal regarding the Foreign Sovereign Immunities Act. After law school, she worked as a judicial law clerk to the Honorable Robert B. Maloney, United States District Judge for the Northern District of Texas.

Fenner regularly speaks and writes on healthcare, employment law and public law matters. Fenner is Vice-chair of the Government and Administrative Law Section and an active member of the Labor and Employment Section of the Oklahoma Bar Association. She also serves on the OBA Professionalism Committee.  Upon invitation, Fenner attended the 2007 OBA Leadership Conference. Fenner is a member of the Oklahoma County Bar Association and chairs the Work/Life Balance Committee. She also serves as a volunteer, teaching grade school and high school children law-related and citizenship education. She has served in the past as an officer for the Central Oklahoma Federalist Society. Fenner is a 2005 graduate of Leadership Edmond Class XX.

After spending nine years with the State in various capacities, Fenner returned to private practice in August 2003. She began working for the State as an Assistant Attorney General in 1994, and later served as Assistant General Counsel at the Oklahoma State Department of Health and General Counsel for the Department of Mental Health and Substance Abuse Services. Throughout her legal career, she has represented individuals and various governmental and business entities and practiced primarily in the areas of employment, civil rights and tort litigation and administrative and health care law. She will continue to focus her practice in these areas. Fenner is licensed in Oklahoma and Texas.