David Costello

David Costello is Counsel at Boies Schiller Flexner LLP, where he focuses on complex business and government-related litigation.

Before entering private practice, David served as Chief Deputy Solicitor General in the Florida Solicitor General's Office. In that role, David supervised the State of Florida's civil appellate docket, managed its key trial-court matters, and directed its civil amicus practice. During his tenure, David also served as managing attorney and primary drafter for some of the State's most high-profile litigations, including Planned Parenthood of Southwest and Central Florida v. State, 384 So. 3d 67 (Fla. 2024); Warren v. DeSantis, 125 F.4th 1361 (11th Cir. 2025); Byrd v. Black Voters Matter Capacity Building Institute, No. SC23-1671 (Fla.); and Disney v. DeSantis, 716 F. Supp. 3d 1216 (N.D. Fla. 2024). He has argued several times in the Florida Supreme Court, the United States Court of Appeals for the Eleventh Circuit, and Florida's District Courts of Appeal, and he is a former chair of the Hillsborough County Bar Association's Appellate Practice Section.

David clerked for Judge Charles R. Wilson of the United States Court of Appeals for the Eleventh Circuit and Judge Robert L. Hinkle of the United States District Court for the Northern District of Florida. Between his clerkships, David worked as an associate at Hunton Andrews Kurth LLP. He received his undergraduate degree from the University of Florida and his J.D. from Georgetown University Law Center.