FinCEN's 2019 crypto guidance (May 2019)
FinCEN, the Treasury bureau that enforces the Bank Secrecy Act, issued guidance stating that anonymity-enhancing cryptocurrency services such as mixers, and peer-to-peer exchangers, are money transmitters. The guidance applied rules written for wire transfer companies to software that moves digital coins.
Crypto firms faced new registration demands, and some startups left the U.S. market.
The interpretation became the legal foundation for the mixer prosecutions of the 2020s.
The August 2026 ruling is the judicial enforcement of that 2019 interpretation, extended to software that never touches funds.
