The conflict of treaties and its assessment under the norms of general international law

Andrius Mamontovas


The purpose of this study is to analyze the concept of conflict of treaties in the light of contemporary general international law. According to the author, the conflict of treaties arises when a state party to an earlier treaty concludes or applies a new treaty (or such later treaty enters into force for that state) leading to the violation of obligations arising for that state from the earlier treaty. The author contends that treaty conflict may be resolved by simultaneously applying the Vienna Convention on the Law of Treaties and the law on state responsibility.
After analyzing the provisions of the Vienna Convention and relevant doctrine, author concludes that article 30 of the Vienna Convention shall apply to all treaties having incompatible provisions, irrespective of its limited literal meaning referring to treaties governing “the same subject-matter”.
In the analysis of the contents of article 30, the author advances a number of legal arguments in favor of the criteria of “entry into force” rather than “adoption of the text” for the determination of earlier and later treaties. Author advances the idea that treaty conflict may be entered into by mere conclusion (adoption of the text) of the later treaty, regardless of the fact that such a case is not defined by the wording of the article 30 of the Vienna Convention. This finding is deduced from the legal principles of state responsibility, material breach and treaty modification applicable to such cases irrespective of limited wording of the above mentioned article of the Vienna Convention. The author finalizes the analysis of the Vienna Convention by concluding that the priority of the application of the earlier treaty in case of conflict of treaties is well grounded upon the text of the Vienna convention, as the travaux préparatoires suggests.
In the part of the article dealing with state responsibility the author outlines the main features of the concept of incompatible obligations brought about by the conflict of treaties and notes that in case of conflict of treaties, by default the state shall adhere to the earlier treaty and make appropriate reparation to prior treaty partner. Whereas in regard to the partner of the later treaty such a state shall make reparation for the breach of Article 102 of the UN Charter obliging the defaulting state to publish and register engagements entered into by a state with the Secretariat of the UN, provided the treaty partner was unaware of conflicting treaty obligations.


international law; conflict of treaties; earlier treaty; later treaty; conclusion; international obligation; application of the treaty; priority of application; incompatible obligation; internationally wrongful act; state responsibility

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"Societal studies" ISSN online 2029-2244 / ISSN print 2029-2236