Treaties play a fundamental role in international relations. They are recognized as a source of international law in Article 38 of the Statute of the International Court of Justice. Therefore, the Vienna Convention on the Law of Treaties was adopted in 1969. The Vienna Convention regulates the conclusion and entry into force of treaties. Moreover, it regulates the application and interpretation of treaties as well as the amendment, invalidity and termination of treaties.
According to Article 2 of this multilateral agreement, a 'treaty’ means an international agreement concluded between States in written form and governed by international law. Whether is is embodied in a single instrument or in two or more related instruments and whatever its particular designation. A treaty concluded between one or more States and one or more international organizations, or between international organizations, can also be referred to as a treaty. According to Article 38 of the Statute of the International Court of Justice, international conventions must be applied by the Court, when deciding disputes that are submitted to it. These conventions can be general or particular. They establish rules expressly recognized by the contesting states. From this principle, one can conclude that international conventions are one of the principal sources of public international law.
This Research Guide is intended as a starting point for research on the Law of Treaties. It provides the basic materials available in the Peace Palace Library, both in print and electronic format. Handbooks, leading articles, bibliographies, periodicals, serial publications and documents of interest are presented in the Selective Bibliography section. Links to the PPL Catalogue are inserted. The Library's subject headings (keywords) Treaties, and Law of Treaties are instrumental for searching through the Catalogue. Special attention is given to our subscriptions on databases, e-journals, e-books and other electronic resources. Finally, this Research Guide features links to relevant websites and other online resources of particular interest.
Sources of international law
Treaties
- Council of Europe Treaty Series
- HeinOnline Treaties and Agreements Library
- Max Planck Encyclopedia of Public International Law
- Oxford Public International Law, 50th Anniversary: Vienna Convention on the Law of Treaties
To celebrate the VCLT’s golden anniversary, OPIL has put together a collection of articles and chapters exploring its origins and entry into force, as well as an assortment of commentary on some of the current debates such as treaty terminations, Article 62, and the obscure doctrine of rebus sic stantibus. All content is free to read until 31st July 2019.
The Lecture Series contains a permanent collection of lectures of enduring value on virtually every subject of international law given by leading international law scholars and practitioners from different regions, legal systems, cultures and sectors of the legal profession. Lectures on the Law of Treaties (Depositary Functions; Interpretation and Registration) by Ms. Annebeth Rosenboom and Mr. Jan Klabbers.
Collections and compilations of treaties and other documents of international law
Case-law
UN Declarations and Resolutions
The resolutions and decisions of the United Nations General Assembly and Security Council may provide valuable information on treaties and the law on treaties. Although they cannot themselves constitute international law or serve as conclusive evidence of a rule of customary law, such resolutions do have value in providing evidence of existing or emerging law. This point of view has been acknowledged by the International Law Commission.
As every Member State has been recognized and has a vote in the UN General Assembly, finding General Assembly resolutions that passed unanimously or near-unanimously may serve as an excellent starting point in the legal research process. Pay attention to the language of the resolution. Those with firm obligations versus those that are merely aspirational or advisory in nature are more likely to be considered valuable as evidence of customary international law.
→ Official Document System Search. ODS is the UN's Official Document System. You can search for UN declarations, resolutions and other documents by keywords, then narrow your search.
→ Start Your Research: (7) Resolutions and Decisions of International Organizations.
Soft law
Reference works
- Aust, A., Modern Treaty Law and Practice, New York, Cambridge University Press, 2013.
- Barrett, J., and R. Beckman, Handbook of Good Treaty Practice, Cambridge, Cambridge University Press, 2020.
- Cannizzaro, E. (et al.) (eds.), The Law of Treaties Beyond the Vienna Convention, Oxford, Oxford University Press, 2011.
- Chesterman, S. (et al.) (eds.), The Oxford Handbook of United Nations Treaties, Oxford, Oxford University Press, Forthcoming Aug. 2019.
- Corten, O, and P. Klein (eds.), The Vienna Conventions on the Law of Treaties: A Commentary, Oxford, Oxford University Press, 2011.
- Dörr, O., and K. Schmalenbach (eds.), Vienna Convention on the Law of Treaties: a Commentary (2nd ed.), Heidelberg , Springer, 2018.
- Gardiner, Richard K. Treaties. First Edition, Oxford University Press, 2023.
- Gardiner, R., Treaty Interpretation (2nd ed.), Oxford, Oxford University Press, 2017.
- Hollis, D.B. (ed.), The Oxford Guide to Treaties, Oxford, Oxford University Press, 2020.
- Klinger, J. (et al.) (eds.), Between the Lines of the Vienna Convention?: Canons and Other Principles of Interpretation in Public International Law, Alphen a/d Rijn, Kluwer Law International, 2019.
- Kolb, R.,The Law of Treaties. An Introduction, Second edition, Cheltenham, Elgar, 2023.
- Linderfalk, U., On the Interpretation of Treaties: The Modern International Law as Expressed in the 1969 Vienna Convention on the Law of Treaties, Dordrecht, Springer, 2007.
- Luján Flores, María del, et al. Derecho de Los Tratados : Actuales Desafíos. Fundación de Cultura Universitaria, 2023.
- Oliveira Mazzuoli, V. de, Direito dos tratados, 2a̲ edição revista, atualizada e ampliada, Rio de Janeiro, Editora Forense, 2014.
- Oliveira Mazzuoli, V. de, The Law of Treaties: A Comprehensive Study of the 1969 Vienna Convention and Beyond, Rio de Janeiro, Editora Forense, 2016.
- McNair, A.D., The Law of Treaties, Oxford, The Clarendon Press, 1961.
- Villiger, M.E., Commentary on the 1969 Vienna Convention on the Law of Treaties, Leiden, Nijhoff, 2009.
Recent books and peer-reviewed articles
- Beneyto, J.M. and C. Jiménez Piernas (eds.), Galimberti Díaz-Faes, S. et al., Derecho de Los Tratados, Valencia, Tirant lo Blanch, 2023.
- Bianchi, A. and F. Zarbiyev, Demystifying Treaty Interpretation, Cambridge, Cambridge University Press, 2024.
- Kofler, Georg, et al., editors. Tax Treaty Interpretation in Light of the Vienna Convention on the Law of Treaties. Kluwer Law International, 2025.
- Rydberg, Agnes Viktoria. The Duty to Safeguard the Object and Purpose of Pending Treaties : A Closer Examination of Article 18 Vclt. Brill/Nijhoff, 2024.
- Xiouri, M., The Breach of a Treaty. State Responses in International Law, Leiden, Brill Nijhoff, 2021.
For all peer-reviewed articles in the PPL Catalogue, click here.
Periodicals, serial publications
- A Complete Collection of the Treaties and Conventions, and Reciprocal Regulations, At Present Subsisting between Great Britain and Foreign Powers, and of the Laws, Decrees and Orders in Council Concerning the Same; So Far as They Relate to Commerce and Navigation, to the Repression and Abolition of the Slave Trade; and to the Privileges and Interests of the Subjects of the High Contracting Parties
- A Guide to the United States Treaties in Force
- Air Laws and Treaties of the World
- Australian Treaty Series
- Bulletin of Treaty Information
- Compilation of Treaties in Force
- Competent National Authorities Under the International Drug Control Treaties
- Consolidated Native Law Statutes, Regulations, and Treaties.
- Consolidated Treaty Series
- Council of Europe Treaty Series = Série des Traités du Conseil de l'Europe.
- Current Treaty Index ... : A Cumulative Index to the United States Slip Indexes and Treaties
- Der Friedensvertrag; Zeitschrift für Rechts- und Wirtschaftsfragen
- Estado de los Tratados y Convenciones Interamericanos = Status of Inter-American Treaties and Conventions = Relação dos Tratados e Convenções Interamericanos = État des Traités et des Conventions Interaméricains
- European Conventions and Agreements
- European Journal of International Law 24 (2013), No. 4.
- Eur-lex
- European Treaty Series
- Guide to Treaties in Force
- Hein's United States Treaties and Other International Agreements Current Microfiche Service
- Hertslet's Commercial Treaties: A Complete Collection of the Treaties and Conventions, and Reciprocal Regulations, at Present Subsisting Between Great Britain and Foreign Powers
- Intellectual Property Laws and Treaties
- International Treaties and Conventions ... : Texts of International Treaties and Conventions in the Preparation of Which Australia Participated But to Which Australia Did Not become a Party During
- Labour Law Documents : Treaties and Legislation on Labour and Social Security
- Law and Treaty Series (Pan American Union)
- List of Treaties Submitted to the Senate
- Overenskomster Med Fremmede Stater (Norway)
- Recueil des Traites de la France
- Recueil des Traités et Accords de la France
- Recueil des Traités et Conventions Conclus Par le Royaume des Pays-Bas Avec les Puissances Étrangères, Depuis 1813 Jusqu'à Nos Jours
- Recueil des Traités et des Engagements Internationaux Enregistrés par le Secretariat de la Société des Nations = Treaty Series : Publication of Treaties and International Engagements Registered With the Secretariat of the League of Nations
- Recueil des Traités et des Engagements Internationaux Enregistrés par le Secrétariat de la Societé des Nations Treaty Series and International Engagements Registered With the Secretariat of the League of Nations
- Recueil International des Traités du XXe Siècle : Contenant l'Ensemble du Droit Conventionnel Entre les États et les Sentences Arbitrales (Textes Originaux avec Traduction Française).
- Registro de Tratados (Spain)
- Relación de los Tratados y Convenciones Panamericanos = Status of the Pan American Treaties and Conventions = Relacão dos Tratados e Convenções Pan-Americanos = État des Traités et des Conventions Panaméricains
- Répertoire de Traités Internationaux et d'Actes Législatifs = Chronology of International Treaties and Legislative Measures
- Serie Sobre Tratados (Pan American Union)
- Signatures, Ratifications, Acceptances, Accessions, etc. Concerning the Multilateral Conventions and Agreements in Respect of Which the Secretary-General Acts as Depository
- Sino-foreign Treaties
- Statement of Treaties and International Agreements
- Statutory Compilation of the Indian Law Survey. A Compendium of Federal Laws and Treaties Relating to Indians
- Studies on the Law of Treaties
- Sveriges Internationella Överenskommelser
- Sveriges Överenskommelser Med Främmande Makter
- Tax Treaties Between Developed and Developing Countries Report
- Taschenbuch der Noten, Pakte und Verträge
- Three Centuries of Treaties of Peace and Their Teaching
- Tractatenblad van het Koninkrijk der Nederlanden
- Traités Internationaux et Actes Législatifs
- Tratados Publicos y Acuerdos Internacionales de Venezuela
- Travaux Préparatoires of Multilateral Treaties
- Treaties and Agreements With and Concerning China 1894-1919
- Treaties and Other International Acts of the United States of America
- Treaties and Other International Agreements of the United States of America, 1776-1949
- Treaties and Other International Acts Series
- Treaty Information Bulletin
- Treaties in Force : A List of Treaties and Other International Acts of the United States in Force
- Treaty Series (New Zealand)
- Treaty Series (OAS)
- Treaty series (Pakistan)
- Treaty Series (UN)
- United Nations Treaty Collection
- United States Treaties and Other International Agreements
- Verträge der Bundesrepublik Deutschland. Serie A, Multilaterale Verträge
Bibliographies
Dictionaries
- International Law Commission Draft Articles on the Law of Treaties with commentaries, 1966
- International Law of Treaties (an Introduction to International Treaty Law, by Walter Gehr)
- Resource Guide on Treaties, ASIL
- United Nations Conference on the Law of Treaties, 1968-1969
- United Nations Treaty Collection
- United Nations Treaty Reference Guide, Definition of Key Terms
- Vienna Convention on the Law of Treaties 1969
- Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations
- Council of Europe Treaty Series
- International Law Commission on Law of Treaties