Thomas Boyd has spent the vast majority of his almost 40 years in litigation and trial practice with the Minneapolis-based Winthrop & Weinstine, where he is one of the firm's earliest members and a noted mentor. Throughout his career, Boyd has earned trial and appellate victories influential enough to shape law at the national level. He represented the Minnesota Chamber of Commerce in challenging a 2023 Minnesota law that broadly barred “foreign-influenced corporations” from contributing to state elections; he led the constitutional challenge under the First Amendment, securing summary judgment and a permanent injunction in January 2025. The decision has drawn national attention as other states consider similar laws.