@AT1ST Depends what remedies exist under both the MLAT and Swiss law. I'm not sure if they could challenge in US court, Swiss court, or both. In US court, companies can move to quash a subpoena, but if a magistrate judge found probable cause, that would probably be a difficult battle. Not to mention the grounds for quashing a subpoena in the first place are very limited, and I don't think that any remedy is even available here but am not an expert (https://www.law.cornell.edu/rules/frcp/rule_45) Once the case gets the court - and it doesn't seem it ever did here - there could be motions to suppress the evidence on the grounds it was illegally obtained. That seems unlikely to prevail here, especially given that analysis would probably be under US law, not Swiss law. There could also be other challenges to the case, i.e. first amendment challenges, but without knowing the facts its hard to know how successful those challenges would be. All of that is so far down the road that it wouldn't be in Proton's calculus. I am not a lawyer, take everything I said with a lot of skepticism.