As the U.N. Charter’s drafters might have predicted, various categories of cases have arisen since 1945 in which states have sought to use force in situations not expressly contemplated by the treaty text. Those who view the Charter as a “living instrument” urge flexibility in interpretation when approaching these nonstandard cases. But they also recognize that allowing excessive flexibility will destabilize the Charter. As a result, some states and scholars seek to promote constrained flexibility by proposing multi part tests to guide state decision making in these nontraditional cases. The MPTs propound on the meaning of sparse texts by articulating specific, legalistic elements or factors against which states may evaluate their contemplated actions.
This Article identifies the common use of MPTs in the jus ad bellum to structure and assess state uses of force in nontraditional contexts. Analytically, it explores why states and scholars turn to MPTs, arguing that MPTs emerge where treaty amendments or Security Council authorization are unlikely. Although not binding on states that have not adopted them, MPTs promote law specification and development and offer a way to reduce interstate conflict. The Article also argues that an MPT will garner more support when it is more rule like and when it closely tracks the underlying Charter or customary rule on which the MPT expounds. Using that analysis, it predicts that MPTs in the area of humanitarian intervention are likely to encounter continued skepticism, at least in the near term.
Ashley S. Deeks, Multi-Part Tests in the Jus ad Bellum, 53 Houston Law Review, 1035–1064 (2016).