Disputes relating to the time aspect may arise in a variety of forms in the context of investment treaty arbitration. They may arise in the form of a procedural issue, or a jurisdictional issue, or an issue of substance, and they may also arise in the interface between these fields or categories. This paper deals with this latter aspect of the problem and focuses on whether there is a distinction between jurisdiction ratione temporis and substantive protection ratione temporis. Recent arbitral jurisprudence suggests that such a distinction may indeed be made, and in certain circumstances should be made, although it remains less than clear what its practical relevance might be.
Indeed, the question, as formulated, appears on its face somewhat academic. Is it not the case that the jurisdiction ratione temporis of an arbitral tribunal established under an investment treaty and the substantive protections available under the treaty must be co-extensive in terms of time in the sense that tribunals generally have no jurisdiction ratione temporis to deal with acts or omissions that occurred prior to the entry into force of the treaty? And is it not the case that they must be co-extensive precisely because the State parties to the treaty are required to comply with the substantive obligations the treaty imposes only as of the date the treaty enters into force, and not before? Moreover, even if the tribunal did have jurisdiction to deal with such existing disputes based on the express terms of the treaty or otherwise, would such jurisdiction be of any practical relevance if the substantive obligations created by the treaty apply only as of the date the treaty entered into force and were not applicable at the time when the act or omission in question occurred?