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Guide to Treaty Research

Written by Nam Jin Yoon
Maintained by Nam Jin Yoon
Last Updated June 2020

Introduction to Treaty Research

This guide is intended to help legal researchers find treaties. Because there is no single one-stop repository for all treaties, treaty research requires an understanding of what treaties are and what types of treaties are covered by the various finding aids and full-text sources available to you.

Treaty citations and short form abbreviations in this guide are intended for US legal researchers interested in publishing in the United States, and are governed by Rule 21.4 of the Bluebook.

Please send all questions and comments regarding this guide to Nam Jin Yoon. If you are a Columbia affiliate and have a research question, please send an email from your LionMail account to

What is a Treaty?

A treaty is an agreement between two or more nations. Treaties may be referred to by other names (e.g., accords, agreements, charters, covenants, conventions, pacts, and protocols), but the choice of name holds no legal significance in international law.

Treaties are often categorized as bilateral (between just two countries) or multilateral (between three or more countries). Understanding these categories and the following terms will help guide your treaty research:

Entry into force – Date on which the treaty becomes legally binding on parties. This date is often specified in the treaty itself, and may differ for different parties.
Ratification – Formal acceptance of the terms of a treaty by a party.
Reservation – Statement made by a nation upon signing or ratifying a treaty that excludes or modifies the legal effect of certain provisions of the treaty for that party.
Signature – Indication of an intent to be bound by the terms of the treat.y

The UN Treaty Collection also offers a helpful Glossary for treaty-related terminology.

Secondary Sources for Treaty Law

If you are unfamiliar with treaty law and would like further context, we recommend the following secondary sources.

For an introductory overview of treaties and treaty law:

Max Planck Encyclopedia of Public International Law, edited by Rüdiger Wolfrum
The “Treaties” article by Malgosia Fitzmaurice provides a concise overview, and the many following sub-entries will provide both background and useful bibliographies on various aspects of treaty law.
UN Treaty Handbook (2012)
Intended as a practical guide to assist States in becoming parties to international treaties, this handbook contains useful diagrams and flow charts that are useful for understanding treaty procedure.

For more in-depth treaty law coverage:

Modern Treaty Law and Practice, 3rd edition by Anthony Aust (2013) (eBook link).
Comprehensive treatise on treaty law from a practitioner’s viewpoint.
The Oxford Guide to Treaties, edited by Duncan B. Hollis (2012)
This guide provides a mix of academic scholarship and practice-oriented articles discussing how treaties are formed, applied, and interpreted.
Treaty Interpretation, 2nd edition by Richard K. Gardiner (2015)
This treatise focuses on the rules of treaty interpretation codified in the Vienna Convention on the Law of Treaties.

How to Find Treaties Using this Guide

To quickly find the text of a treaty, ask yourself the following two questions:

1. Is the United States a party to the treaty?
a. If so, go to U.S. Treaties. If not, proceed to question two.
2. Is the treaty bilateral or multilateral?
a. If there are only two parties, go to Bilateral Treaties.
b. If there are more than two parties, go to Multilateral Treaties.

If you are unsure of the answers to the above questions or if you cannot locate your treaty using the resources provided in the above sections, you can also try finding treaties by topic.

If you are researching pre-1949 treaties that are no longer in force, please read our Guide to Researching Historical Treaties.

U.S. Treaties

When dealing with treaties to which the United States is a party, it’s important to understand the difference between a treaty and an executive agreement under U.S. law. The United States reserves the word “treaty” for an agreement that is made “by and with the Advice and Consent of the Senate” (Article II, Section 2 of the Constitution). Agreements made by the President that are not submitted to the Senate are called “executive agreements.” While executive agreements are not treaties under U.S. law, they may still be considered legally binding treaties under international law.

For more information on the ratification and implementation of treaties under U.S. law, see Treaties and Other International Agreements: The Role of the United States Senate, S. PRT. 106–71 (2001).

Indexes and Finding Aids for U.S. Treaties & Agreements

Over the years, U.S. treaties have been published in a number of different sources, each often known by its citation shorthand. Since treaties still in force can date back centuries, finding the official full-text sources for a treaty can be a tricky endeavor. Rather than individually checking each full-text source, we recommend starting your search by first consulting one of the following indexes or finding aids to find the relevant citations for your treaty:

Treaties in Force (TIF)
Usually published annually by the State Department, Treaties in Force is the best source for finding citations for U.S. treaties and other international agreements that are currently in force. The current 2019 edition is available online, split into bilateral and multilateral sections. Bilateral treaties and agreements are arranged by country, and multilateral treaties and agreements are arranged by subject.
Kavass's Guide to the United States Treaties in Force (Kavass)
Kavass supplements Treaties in Force by providing additional ways to sort treaties, including a combined subject index for bilateral and multilateral treaties, as well as treaties organized by country, subject, date, and number. Available through HeinOnline and on the 4th Floor / Reference Office, KZ235 .G85.
Kavass’s Current Treaty Index
Whereas Kavass’s Guide to the United States Treaties in Force is intended as a companion to Treaties in Force, Kavass’s Current Treaty Index supplements Kavass’s Guide by indexing more recently concluded treaties and agreements. These include both treaties published in slip form in Treaties and Other International Acts Series as well as treaties not yet published in TIAS, which are then assigned a separate “KAV number.” Available through HeinOnline and on the 4th Floor, KZ235 .U58 1991 Suppl..

Full-Text Sources for U.S. Treaties & Agreements

Under Bluebook Rule 21.4.5, U.S. treaties and international agreements should be cited by the following sources, in the following order of preference: U.S.T. (or Stat.); T.I.A.S. (or T.S., or E.A.S.); U.N.T.S.; Senate Treaty Documents or Senate Executive Documents; the Department of State Dispatch; Department of State Press Releases. Many treaties will have more than one citation and source.

For multilateral treaties to which the United States is a party, a parallel citation may be added from one source published by an international organization (e.g., U.N.T.S.). Doing so will make your research more accessible for international readers, who may not be able to track down U.S. sources.

The following are “official” full-text sources for U.S. treaties and international agreements:

Treaties and Other International Acts Series (T.I.A.S.) [1945 – Present]
Since 1945, U.S. treaties and agreements that have entered into force have been published in this series. Since 2006, T.I.A.S. has been published in electronic form only. Note that under Bluebook R. 21.4.5, you should cite to T.I.A.S. only if a U.S.T. or Stat. citation is unavailable. Available through the Department of State [1981 – Present], HeinOnline [1950 – Present], and on the 2nd Floor, JX235.9 A4.
U.S. Treaties and Other International Agreements Series (U.S.T.) [1950 – 1984]
From 1950 to 1982, slip copies of the T.I.A.S. treaties were bound into volumes as part of this series. Available through HeinOnline and ReCAP, JX235.9 A5.
Statutes at Large (Stat.) [1776 – 1950]
From 1776 to 1950, treaties and international agreements that entered into force were published in the Statutes at Large.
Treaty Series (T.S.) [1795 – 1945]
From 1795–1945, treaties that entered into force were included in this series. Most executive agreements prior to 1929 were also included in this series.
Executive Agreement Series (E.A.S.) [1929 – 1945]
From 1929–1945, agreements that entered into force were included in this series.
Senate Treaty Documents [1981 – Present] / Senate Executive Documents [1789 – 1980]
When treaties are signed and submitted to the Senate, they are published in this collection (Senate Treaty Documents, formerly Senate Executive Documents).

If you cannot find the full text of your treaty from the official sources listed above, Bluebook Rule 21.4.5 allows for the citation of unofficial sources. The following unofficial sources may be helpful to you:

International Legal Materials (I.L.M.) [1962 – Present]
Under Bluebook R. 21.4.5(c), you should cite to this series if you cannot cite to any of the sources listed above. International Legal Materials publishes select U.S. treaties and executive agreements along with other international law documents. Access is available through HeinOnline [1962 – 2017] and Cambridge University Press [2012 – Present].
KAV Agreements [1950 – Present]
Available through HeinOnline, this source provides the full text of U.S. treaties and agreements since 1950 that have not yet been published in U.S.T. or T.I.A.S. In short, this is the most comprehensive source for recent and unpublished U.S. treaties and agreements.

Updating Treaties

Once you’ve located your treaty or international agreement, you’ll likely want to make sure the information regarding the treaty’s status (e.g., whether it’s in force, whether it’s been ratified, list of parties) is up to date.

To see if a U.S. treaty or agreement has entered into force, start with the latest edition of Treaties in Force (TIF). Each entry should provide the date on which the treaty entered into force.

If the treaty is recent and has not yet been ratified, you can check on the status of treaties received and approved by the current congress on the Senate’s webpage for Treaties.

If the treaty was submitted to the Senate in the past but have not yet received Senate advice and consent to ratification, you can find it on the State Department’s Treaties Pending in the Senate.

Multilateral Treaties

For non-U.S. multilateral treaties, the research process largely mirrors the process for U.S. treaties: (1) find a citation or link in an index; (2) use the citation to locate the full text of the treaty; and (3) check the current status of the treaty to ensure your information is up to date.

Multilateral treaties will often designate a depository (usually, the United Nations or the country on which the treaty was signed), who then keeps custody of the original text of the treaty, accept all notifications and documents related to the treaty, register the treaty, and notify all relevant acts to the treaty's parties. For more information on the role of a treaty depository, see the Summary of Practice of the Secretary-General as Depositary of Multilateral Treaties and Article 77 of the Vienna Convention on the Law of Treaties.

Many treaties are also separately registered with the United Nations, which then publishes the treaty in its United Nations Treaty Series. This practice is in accordance with Article 102 of the UN Charter, which states that "every treaty and every international agreement entered into by any Member of the United Nations after the present Charter comes into force shall as soon as possible be registered with the Secretariat and published by it."

Reservations are statements made by a nation upon signing or ratifying a treaty that excludes or modifies the legal effect of certain provisions of the treaty for that party.

The following indexes are useful for multilateral treaties:

Multilateral Treaties Deposited with the Secretary-General (MTDSG)
This database provides up-to-date information regarding over 560 major multilateral treaties deposited with the Secretary-General of the United Nations. Useful information provided by this database include subsequent treaty actions, texts of reservations, declarations, and objections, and a participation table showing each party’s relevant treaty actions.
Cumulative Index to the United Nations Treaty Series [1946 – Current]
Available online through the United Nations Treaty Collection and HeinOnline, this index consists of a Chronological Index and an Alphabetical Index for the treaties in the UN Treaty Series. The index provides relevant dates, parties, Treaty registration number, and subject headings.
Multilateral Treaty Calendar [1648 – 1995]
Also available online through HeinOnline’s Treaty Index, this chronological index provides citations to full-text sources along with the subject, date of entry into force, and parties.
Electronic Information System for International Law (EISIL) [1900 – Present]
While this index is currently inaccessible as it migrates to a new platform, EISIL is a searchable index providing linked citations and basic information for treaties dating back to 1900.

The following sources provide full-text multilateral treaties:

United Nations Treaty Series (U.N.T.S.) [1945 – Present]
The United Nations Treaty Series is available online as a fully searchable database. It contains bilateral and multilateral treaties and international agreements registered or filed and recorded by the Secretariat since 1945.
League of Nations Treaty Series (L.N.T.S.) [1920 – 1948]
Also part of the U.N. Treaty Collection, the League of Nations Treaty Series includes bilateral and multilateral treaties registered with the League of Nations from 1920 – 1948.
International Legal Materials (I.L.M.) [1962 – Present]
See description supra at Full-Text Sources for U.S. Treaties & Agreements.
Organization of American States Treaty Series (O.A.S.T.S.) [1940 – Present]
This collection covers Inter-American multilateral and bilateral treaties from 1940 through the present.
European Treaty Series (E.T.S.) [1949 – 2003] / Council of Europe Treaty Series (C.E.T.S.) [2004 – Present]
The European Treaty Series (and its predecessor Council of Europe Treaty Series) is a searchable database with full text and accompanying reports of treaties dating back to 1949.
International Legislation [1919 – 1945]
Collection of multilateral treaties from 1919 to 1945. Includes treaties never entered into force.
Consolidated Treaty Series [1648 – 1919]
Collection of bilateral and multilateral treaties from 1648 to 1919. All texts are in their original languages. Only available in print from Offsite Clancy, JX120 P35.

To check the current status of multilateral treaties, try the following resources:

Multilateral Treaties Deposited with the Secretary-General (MTDSG)
This database provides up-to-date information regarding over 560 major multilateral treaties deposited with the Secretary-General of the United Nations. Useful information provided by this database include subsequent treaty actions, texts of reservations, declarations, and objections, and a participation table showing each party’s relevant treaty actions.
Treaties in Force (Section 2: Multilateral Treaties and Other Agreements)
In Section 2 of the latest TIF, you will find depository information for each multilateral treaty listed along with an introductory section titled “Depository Websites” providing links to depository countries and agencies. Going directly to these depositary websites is a good way to check the latest status of relevant treaties.

Bilateral Treaties

When dealing with treaties to which the United States is not a party, it’s generally more difficult to find bilateral treaties than it is to find multilateral treaties. States are not obligated to deposit bilateral treaties with the United Nations, and these treaties are less likely to be collected in large sets.

For non-U.S. bilateral treaties, your best bets are to look in: (1) general databases and collections publishing both bilateral and multilateral treaties; (2) official gazettes and country treaty series of the relevant parties; and (3) subject-specific treaty databases.

General Databases

The two best general databases to start your bilateral treaty search are the previously-mentioned United Nations Treaty Collection (where you can filter by “Treaty type” and select “Bilateral”) and HeinOnline’s World Treaty Library (where you can search HeinOnline’s extensive collection).

Official Gazettes and Country Treaty Collections

Many countries publish their bilateral treaties in official gazettes or collect their treaties on government websites and repositories.

To find official gazettes for specific countries, we recommend going to the Foreign Law Guide, browsing to the relevant country, and clicking on the “Official Gazette” link under Primary Sources. Other good directories for official gazettes include the Library of Congress’s Guide to Law Online and GlobaLex’s Foreign Law Research guides.

To find national treaty series and collections online, we recommend checking WorldLII’s International Treaties Collection and the United Nations Audiovisual Library of International Law’s List of Treaty Collections.

Finally, the World Treaty Index [1900 – 1980] contains bilateral treaties and a list of “Source Codes” in its Thesaurus. Because the World Treaty Index was last updated for treaties completed by 1980, these sources may no longer exist and must be updated.

Finding Treaties by Topic

A number of various international organizations and federal agencies maintain databases of subject-specific bilateral and multilateral treaties. Some of these databases are arranged by topic below.

Arms Control

Bilateral Investment Treaties (BITs)


Human Rights

Intellectual Property

International Trade


Legal Databases

For treaty research, we recommend using HeinOnline's U.S. Treaties and Agreements Library and World Treaty Library. As a result, many of the treaty sources linked in this guide use HeinOnline where available.

If HeinOnline is unavailable and you are interested in U.S. treaties, both Westlaw and Lexis offer full texts of U.S. treaties.

Other Research Guides

For additional guidance on researching pre-1949 treaties, read our Guide to Researching Historical Treaties. For additional guidance on researching European Union treaties, read our European Union Legal Materials guide.

For more on drafting histories of treaties, go to Yale Law Library’s Collected Travaux Préparatoires and GlobaLex’s À la Recherche des Travaux Préparatoires: An Approach to Researching the Drafting History of International Agreements.

For more on treaty research, read Georgetown Law Library’s Treaty Research Guide and Berkeley Law Library’s Treaties and International Agreements.

Further Assistance and Acknowledgements

Please send any questions and comments regarding this guide to Nam Jin Yoon, Reference Librarian, Arthur W. Diamond Law Library, Columbia Law School.

If you are a Columbia affiliate and have a research question, please send an email from your LionMail account to

This guide is based in part on an earlier treaty guide written by Simon Canick.