Tornado Cash is a decentralized cryptocurrency mixing service built on Ethereum. Its open-source protocol allows users to obscure the trail of their cryptocurrency transactions by pooling funds together, making it difficult to trace the origin and destination of any given transfer.

In August 2022, the U.S. Treasury Department took the unprecedented step of sanctioning Tornado Cash, effectively criminalizing its use by American citizens and businesses. Authorities accused the service of facilitating money laundering, including processing hundreds of millions in stolen funds linked to North Korean hackers. In the wake of the sanctions, Tornado Cash's website was taken down, its GitHub repository removed, and one of its developers arrested in Amsterdam.

The crackdown has sent shockwaves through the crypto and privacy advocacy communities. Proponents argue that Tornado Cash is a neutral tool, akin to VPNs or Tor, with many legitimate uses beyond illicit finance. They warn that banning a piece of code sets a dangerous precedent and undermines fundamental rights to privacy and free speech. On the other hand, regulators contend that mixers like Tornado Cash have become a haven for cybercriminals and rogue state actors, necessitating more aggressive enforcement.

As the legal and political battle unfolds, Coin Center, a leading crypto policy think tank, has taken up the mantle of defending Tornado Cash and its users. Director of Research Peter Van Valkenburgh, who also serves as a board member for Zcash, joins The Dynamist today to walk through this crackdown and the implications for decentralized finance and open-source software today. Luke Hogg, director of policy and outreach, guest hosts this episode. You can read more from Peter on this issue here.