Could other countries or individuals of other countries take legal action against the USG? There must be something stopping people from suing etc.
The best that could do in the short term is embarrass the US publicly, as they would probably come up with some legal or moral excuse to not cooperate with the charges ("terr'ism").
The US government likes to have the best of both worlds; everyone else has to conform to the US' most stringent/"imaginative" interpretation of international agreements, but when the US itself has a charge to answer, it bats them off like a fly buzzing around their head.
Walks like an empire, talks like an empire. For some reason, no-one ever says it though... I might see if I can start a trend. "Imperialist US" sounds too polite somehow, "US empire" sounds less euphemistic.