Brian Nelson: Leading the Charge Against Tornado Cash

When Brian Nelson left the U.S. Treasury Department late this year, he became a leading crypto voice working on Vice President Kamala Harris' presidential campaign. Nelson had previously carved himself an outsized role with respect to crypto as the Treasury's undersecretary for terrorism and financial intelligence, leading its charge against digital asset mixing services and connections to terrorists, and trying to increase the federal government's reach into the sector.

Nelson focused on crypto's dark side, arguing that the technology poses a danger as a tool for funding international terrorism and criminal cartels and viewing anonymizing services such as Tornado Cash as a means for bad guys to move cash with impunity. To that end, Nelson sought to shift the tools of government to put a stop to that technology.

After Nelson led the push to sanction Tornado Cash in 2022, he became a point person for the federal government's battles against the way the crypto sector does business. Under his watch, the Treasury became a crypto antagonist — well beyond what the Internal Revenue Service has done in proposing tax standards that could threaten decentralized finance (DeFi). Nelson shepherded an effort by the department's financial crimes arm to label mixing services a "primary money laundering concern," insisting that he was aiming for necessary transparency rather than a blanket ban on mixers.

But just last month, his Treasury legacy took a heavy blow from a federal appeals court, which ruled that the department was out of bounds when it went after the software underpinning Tornado Cash transactions. And Nelson's campaign against crypto's illicit finance dangers may soon be further eclipsed by the government's expected sharp turn toward openness to digital assets when Republicans take the wheel in 2025.

This profile is part of CoinDesk's Most Influential 2024 package. For all of this year's nominees, click here.