Is There Such a Thing as Admissibility in Investment Arbitration?

The concepts of jurisdiction and admissibility regularly figure in the reasoning of investment tribunals. Most often, the concept of admissibility is accepted without further reflection and occasionally a delimitation of the concept - particularly in relation to jurisdiction - is attempted. However, only in a few instances have arbitrators questioned the usefulness or even the legitimacy of a concept of "admissibility'' in investment arbitration. This also holds true for legal writings where admissibility - e.g. in relation to jurisdiction and tribunal competence - is discussed without the very existence of this concept in treaty-based investment arbitration being questioned. This paper posits that the concept of admissibility has no role to play in investment arbitration. There is no need to make any inquiry into whether a certain objection concerns the "admissibility'' of a claim. If admissibility is discussed at all it must proceed further to a decision on jurisdiction or - alternatively and exceptionally - a finding that the "admissibility'' objection is relevant for the merits.