The US Treasury is finalizing a “mixer rule” under the PATRIOT Act to ban privacy tools in crypto, while Congress revives legislation granting sweeping powers to block digital asset transactions. Critics warn this could criminalize everyday practices like swaps and wallet splitting, threatening privacy and open-source development.

The story centers on a U.S. regulatory and legislative push to use USA PATRIOT Act authorities against cryptocurrency privacy tools, with critics warning that the emerging framework could reach far beyond traditional “mixers” to encompass common on-chain privacy and self-custody practices. On the regulatory side, the U.S. Treasury’s Financial Crimes Enforcement Network (FinCEN) has already issued an October 2023 Notice of Proposed Rulemaking under Section 311 of the PATRIOT Act, designating convertible virtual currency (CVC) mixing as a “class of transactions of primary money laundering concern.” The proposal defines CVC mixing broadly as any facilitation of virtual currency transactions that obscures source, destination, or amount, regardless of protocol or tool. It would require Bank Secrecy Act‑regulated financial institutions to file extensive reports on any transactions they know, suspect, or have reason to suspect involve CVC mixing, particularly when there is an international nexus. Commentary highlighted in coverage of the “mixer rule” notes that Treasury and FinCEN are now explicitly applying PATRIOT Act Section 311, historically used against foreign banks and jurisdictions, to categories of crypto transactions, signaling an intent to treat many privacy‑enhancing techniques as inherently suspect. In parallel, Congress is revisiting legislation to expand Treasury’s unilateral power to restrict or block digital asset activity. Reporting tied to this debate points to the Special Measures to Fight Modern Threats Act, initially introduced in 2022 by Rep. Jim Himes, which would broaden the Section 311 toolkit so Treasury could prohibit categories of transactions it deems risky, potentially without traditional notice-and-comment constraints. Policy analysts such as Nicholas Anthony have warned that such authority could be used, for example, to bar U.S. banks from dealing with crypto transactions validated by foreign miners, and that the combination of an expansive “mixer” designation plus new special-measures powers could chill open-source development, DeFi protocols, and routine practices like swapping tokens, splitting wallets, or using disposable addresses. While Treasury has more recently acknowledged in a separate report that mixer tools can have legitimate security uses, the overall direction of these measures raises significant concerns among privacy advocates, developers, and some industry participants about overbroad surveillance, potential criminalization of ordinary self-custody behaviors, and the precedent of applying counterterrorism-era authorities to general-purpose blockchain software.

✨ AI-generated background, compiled from web sources — not editorial content.

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