Van Loon plaintiffs appealed in the Fifth Circuit on September 2 challenging the U.S. Treasury Department's decision to place Tornado Cash on the Specially Designated Nationals (SDN) list. The plaintiffs argued that the Treasury Department's imposition of sanctions on the open-source project without clear guidelines could threaten programmers' First Amendment rights. Van Loon and his team sued the Treasury in September 2023, accusing it of exceeding its authority.