ChainCatcher reported that the Van Loon plaintiffs appealed to the Fifth Circuit Court on September 2, suing the U.S. Treasury Department's decision to include Tornado Cash on the Specially Designated Nationals (SDN) list. The plaintiffs believe that the Treasury Department's sanctions on this open source project without clear guidelines may threaten programmers' First Amendment rights. Van Loon and his team sued the Treasury Department in September 2023, accusing it of exceeding its authority.

Tornado Cash was sanctioned for alleged money laundering, with the government claiming that the platform has been involved in more than $7 billion in illegal funds since 2019. The Electronic Frontier Foundation (EFF) supported the lawsuit, fearing that government sanctions would have a chilling effect on open source software development. The local court had previously dismissed the lawsuit, arguing that the sanctions were limited to transactions involving Tornado Cash smart contracts and would not affect the development and discussion of open source code. However, the EFF and other digital rights advocates remain concerned about the broad impact of the case, emphasizing the importance of protecting programmers' rights.