Sean Berry practiced law with Musick, Peeler & Garrett, a civil litigation firm in Los Angeles, from 1987 to 1989, then joined the US Attorney's Office for the Central District of California, where he worked until 1999. That year he moved to the US Attorney's Office for the Northern District of Iowa, where he served until his retirement in 2022. Professor Berry served as United States Attorney, First Assistant United States Attorney, and Criminal Chief. 

Professor Berry has extensive experience investigating and prosecuting complex financial crimes. He taught Federal Criminal Practice at the University of Iowa and trial advocacy at the National Advocacy Center, an arm of the US Department of Justice that provides training to Department prosecutors. Professor Berry also has lectured internationally for the US Department of Justice.