Warren has a long history in the legal community. He is an attorney at the Minneapolis law firm of Fredrikson & Byron, P.A., where he concentrates his practice on corporate, health and tax law. His clients include a variety of businesses, clinics and hospitals. Warren has held leadership positions at Fredrickson & Byron, serving as chairman of the board from 1997-2002 and president and CEO from 1985-1997.
In addition to advising Persolvent, Warren writes and lectures frequently on health, tax, and corporate law topics. He taught business law as an adjunct professor at Macalester College in St. Paul, MN.
Warren currently serves on three charitable boards and five business corporation boards, both public and private. He was also recognized as one of Minnesota's Outstanding Directors by Twin Cities Business.