Power and persuasion in investment treaty interpretation: The dual role of states

States entering into investment treaties establish dual roles for themselves as treaty parties (with an interest in interpretation) and actual or potential respondents in investor-state disputes (with an interest in avoiding liability). By viewing states primarily as respondents rather than also as treaty parties, investment tribunals often ignore the relevance and persuasiveness for interpretation of those parties’ subsequent agreements and practice. The approach proposed here seeks to recalibrate interpretive power between states and tribunals by increasing consideration of such evidence.