a 51% attack that double spends appears to violate the Computer Fraud and Abuse Act. i think even a mere censorship attack would qualify based on that legal theory.

whether it's enforceable is another matter. it carries a prison sentences of 10 years per count, and victims could sue for damages, but this is all theoretical. it's never been done, and the legal theory has never been tested in court. i assume the discovery process would be an absolute nightmare.