The viability of international law rests largely on the viability of treaties as a source of law. In the second half of the twentieth century, the international state system was supported by the development of treaties. States focused the majority of their regime-building efforts on three sets of concerns: restraining interstate conflict, securing human rights, and managing the economic system. States used treaties as the primary tool in the construction of these international institutions and in the codification of these norms. Moreover, treaties shift issues from the political arena into a juridical, rule-based, forum.
The very success of treaties as a policy tool has caused a new dilemma: a surfeit of treaties that often overlap and, with increasing frequency, conflict with one another. For the treaty partners of states that have adopted conflicting treaties, this results in a lack of certainty as to which-if either-treaty would be honored. After the successes of the last fifty years, international law may become increasingly dysfunctional in the first decades of the twenty-first century due to the sheer number of these treaties and the lack of useful, principled, methods to resolve conflicts between them.
This Article addresses a particular cause of fragmentation—unresolved conflicts between treaties—and considers how lawyers and policymakers may respond to the challenges posed by treaty proliferation and conflict. I argue that treaty conflicts are a key underlying cause of fragmentation and that the current rules are inadequate to provide clear, systematic solutions to treaty conflicts.
This Article proceeds in five parts. Part I describes treaty conflicts in terms of the subject-matter and the structure of the treaties. Part II considers techniques of resolving treaty conflicts as alternatives to application of the Vienna Convention on the Law of Treaties (VCLT). Strategies include the drafting of clauses to avoid potential conflicts and the use of interpretive techniques to analyze texts that have already been written. Part III turns to the codification of conflict resolution rules in the VCLT and considers their strengths and weaknesses. Part IV analogizes from other types of textual conflicts, such as conflicts between contracts or between statutes. Part V draws from the previous sections to suggest options in addressing treaty conflicts, including: (a) ending the "same subject-matter" rule in assessing whether or not treaties conflict and in the application of conflict resolution rules; (b) increasing the use of purposive interpretation to assess and resolve treaty conflicts; (c) drafting more detailed conflict avoidance clauses in treaties; and (d) increasing the use of a procedure of assurance to determine the intention of a state that has ratified conflicting treaties. While there is no single solution to this complex dilemma, there are ways to minimize some of the unwanted effects of the proliferation of treaties. Part V also broadens the focus from these specific recommendations and considers the implications of the preceding discussion on the status of international law as a coherent legal system.