The Fifth Circuit has just opined that the smart contracts that comprise the Tornado Cash cryptocurrency tumbler are "not property because they are not capable of being owned", and thus cannot be sanctioned by OFAC.
Some background on the Tornado Cash issue, and some of my thoughts on it from earlier this year: https://www.citationneeded.news/tornado-cash/
Here's the full decision: https://storage.mollywhite.net/pdfs/TornadoCash5Cir.pdf
(CourtListener/RECAP doesn't like it because PACER has a split PDF, apologies)