In several recent International International Centre for Settlement of Investment Disputes (ICSID) cases, investors accused the respondent state of unfairly using its criminal law enforcement powers to advance its position in the arbitration. If the investor turns to the tribunal to intervene by ordering provisional measures, the tribunal finds itself in the most uncomfortable position: at the heavily contested border between state sovereignty and the tribunal’s duty to safeguard the arbitration process. The latest decisions indicate that tribunals are prepared to step in and order the suspension of domestic criminal proceedings when presented with specific evidence of harassment or intimidation of claimants or witnesses. This article reviews these controversial cases, describes the situations in which a request for provisional measures can be successful, what exactly the investor is required to show, and how far tribunals have been willing to go.