The Kenyatta, Gaddafi, and Gbagbo decisions at the International Criminal Court (the ICC or Court) have brought increased attention to the requirements of the principle of complementarity under Article 17 of the Rome Statute. Little attention has been paid to a related admissibility issue: how regional (and sub-regional) tribunals fit with Article 17. This article argues that a genuine prosecution by a lawfully constituted regional tribunal should be seen as the exercise of jurisdiction by the state such that the case is inadmissible before the ICC. This conclusion follows from a proper understanding of the legal nature of the relationship between states and regional tribunals and the contextualized application of the principles of treaty interpretation enshrined in Article 31 of the Vienna Convention on the Law of Treaties (VCLT). Moreover, it is consistent with the values underlying the central principle of complementarity and makes sense as a matter of policy.