The Blockchain Association has thrown fresh support behind six plaintiffs suing the United States Treasury Office of Foreign Assets Control (OFAC) over its sanctions on the crypto mixer Tornado Cash.

In a Nov. 20 amicus curiae brief to a U.S. appellate court, the crypto advocacy group argued OFAC’s decision to sanction the privacy protocol was not only unlawful but exceeded its statutory authority and was both “arbitrary and capricious” — contrary to the U.S. Constitution.

It’s the second amicus brief filed by the Blockchain Association supporting a group of Tornado Cash users appealing a lower court’s ruling that upheld OFAC’s decision to add the cryptocurrency mixer to its list of sanctioned entities.

Blockchain Association senior counsel Marisa Coppel emphasized in a Nov. 20 statement that OFAC needs to focus on sanctioning bad actors rather than outright banning tools, which she claimed it has no authority over.

“OFAC must see Tornado Cash for what it is: a tool that can be used by anyone,” Coppel said. “Rather than sanctioning a tool with a lawful purpose, OFAC should remain focused on the bad actors that misuse such tools.”

“OFAC’s action sets a dangerous new precedent that drastically exceeds their authority and jeopardizes law-abiding Americans’ right to privacy.”

In its brief, the Blockchain Association suggested OFAC should act within the bounds of the law by seeking approval from Congress to ban crypto mixers such as Tornado Cash.

“The proper remedy is to seek legislation from Congress that would provide supplemental authority in the uniquely decentralized digital asset context — not to improperly stretch its existing authorities,”  it said.

“Such a power-grab would be a slippery slope that could threaten all manner of internet-based tools that have heretofore been freely available.”

The Blockchain Association has long held that Tornado Cash has no owner or operator and can function automatically without human intervention or assistance.

OFAC first sanctioned Tornado Cash in August 2022. It alleged that individuals and groups had used the mixer to launder more than $7 billion in cryptocurrencies since 2019, including the $455 million stolen by the North Korea-affiliated Lazarus Group.