An Introduction to Sources for Treaty Research

By Mark Engsberg and Kwanghyuk (David) Yoo

Mark Engsberg is the Director of Library Services and Professor of Practice at the Hugh F. MacMillan Law Library at Emory University School of Law. Before coming to Emory Law, he worked at the Lillian Goldman Law Library at Yale Law School for eight years, where he served as the international and foreign law reference librarian and as head of reference. Professor Engsberg is active in professional legal and law librarianship organizations. Since 2005, he has served as editor-in-chief of the International Journal of Legal Information, published by the International Association of Law Libraries. Engsberg received his M.S.L.I.S. degree, as well as an M.A. and Ph.D. in English literature from the University of Illinois at Urbana-Champaign. He also holds a J.D. from Willamette University College of Law in Salem, OR, and a B.A. from Drury University in Springfield, MO.

Kwanghyuk (David) Yoo is a Law Librarian for Research Services at the Hugh F. MacMillan Law Library at Emory University School of Law. David received an S.J.D. and an LL.M. from the University of Iowa College of Law and an M.L.I.S. from the University of Iowa School of Library and Information Science. He also holds a Ph.D. and an M.A. in International Law, as well as a B.A. in law from Hanyang University School of Law in Seoul, South Korea.

Published May/June 2021

(Previously updated by Mark Engsberg and Mary Beth Chappell Lyles in October 2011 and in March 2016)

See the Archive Version!

1. Introduction

This brief guide provides a broad overview of the sources necessary or helpful to conduct treaty research. It covers background and definitional issues. It is not meant to be a “how to” guide, rather it provides a description of the tools necessary for researching both bilateral and multilateral treaties. This guide mostly covers information for researching treaties to which the United States is a party, but it also includes information useful for researching treaties to which the United States is not a party.

The first portion of the guide contains information about treaties, locating treaties, finding aids for treaty documents, and other related matters. The final segment of the guide provides an overview of electronic sources for conducting treaty research.

2. Treaties and International Agreements

What is a treaty? A treaty is a “formally signed and ratified agreement between two nations or sovereigns.”[1] It is a record of the terms of agreement between two or more countries and is governed by international law.[2] Treaties or treaty-like instruments go by many other names as well, such as

  • Accords
  • Pacts
  • Conventions
  • Agreements
  • Covenants
  • Final Acts
  • Charters
  • Protocols
  • Constitutions for international organizations

Regardless of the various terms used to describe them, apart from some minor differences, they are all basically the same thing.[3]

A treaty binds only the parties to the treaty unless a third State expresses consent to be bound by the treaty.[4] The US government is bound by the provisions of a treaty only when the agreement has been submitted to the US Senate for advice and consent, 2/3 of the Senate vote to approve it, and the President ratifies it.[5] The entire process is called ratification.

International agreements are sometimes confused with treaties, though they are not treaties. Rather, they are executive in nature, can be approved with a simple majority vote of both houses of Congress, or may not even be submitted to Congress for approval. These documents directly govern or implement a great deal of US foreign policy, especially matters related to trade. International agreements are often preferred by various parties because they are often easier and more expeditious to obtain. After all, a 2/3 majority in the Senate—the proportion necessary to ratify a treaty—can be very difficult to achieve.[6]

3. A Brief Treaty Lexicon

When working with treaties, it is important to have a basic understanding of several key terms. As with many areas of the law and legal research, there is a specialized vocabulary, knowledge of which is essential for competent research and full understanding of treaty documents.[7] Below is a quick guide to some of the more important terms, or those terms one most frequently encounters in treaty research:

  • Accession – formal adoption of the provisions of a treaty already agreed upon by other nations.[8]
  • Bilateral – a treaty between just two countries.[9]
  • Enter into force – when the terms of a treaty become binding on a party. A treaty does not necessarily enter into force when the treaty is signed, or even when it is ratified, but it enters into force when parties agree that the treaty enters into force (“enter into force” is a concept usually associated with a specific date and time).[10]
  • International agreements – International agreements are not treaties but are treaty-like. They do not require Senate ratification. The United States says international agreements are not governed by international law. The UN says international agreements are governed by international law. Most of the United States’ formal relations with other countries are governed by international agreements. There are currently about 4000 IAs in force and only about 400 treaties in force where the United States is a party.[11]
  • Multilateral – a treaty between more than two countries.[12]
  • Parties – countries that have ratified a treaty; parties are bound by the terms of the treaty.[13]
  • Ratification – a country’s internal confirmation or acceptance of terms of a treaty agreement, usually accomplished through some form of legislative process.[14]
  • Reservation – a term or terms of a treaty objected to by a country.[15] A country will formally declare it will not be bound by the objectionable term or terms of a treaty usually during the ratification phase.
  • Signatories – countries that have signed a treaty.[16] Signing a treaty indicates intent to be bound by the terms of the treaty but is not necessarily the same as actual accession.

4. Locating Treaty Texts

There is no single correct way to do treaty research, but once one has become acquainted with the principal terms and sources of treaty documents it becomes a relatively simple matter to locate the text of a treaty. It can be a bit more difficult to discover the current status of a particular treaty. And it can be quite a challenge to find information about the negotiation or legislative history of a treaty, travaux preparatoire (unless the US is a party and you’re interested only in the US Senate ratification process).[17]

So where does one locate the text of a treaty or agreement? Where can one find the status and ratification information about a treaty? Sources for locating a treaty text where the United States is a party include the following:

  • United States Statutes at Large – contains US treaties until 1950
  • Treaties and Other International Agreements of the US 1776-1949 (Bevans)
    • In 1950, this became the official source of all US treaties and agreements
    • Volumes are published annually, each with a subject and country index
    • There is an unfortunate 8-10-year lag in publishing
    • Superseded by US Treaties and Other International Agreements (UST) since 1950
  • Treaties and Other International Acts Series (TIAS) (1946-present)
    • Treaties first appear in slip form in the TIAS
    • There is a publishing lag time of 5-6 years
    • Before ratification but before publication in TIAS, some treaties can be found in the Senate Document Series
    • Accessible online through U.S. State Dept. website
  • For many US treaties in various stages, status and ratification information can be accessed without cost online via United States Treaties (Law Library of Congress), Govinfo, and the website of the Senate Foreign Relations Committee.

There are many finding aids for treaties to which the US is a party. Here are six of the most important ones, along with a brief description of the salient features of each resource:

  • Treaties in Force (TIF)
    • Covers treaties from 1950 to present
    • Annual publication
    • Arranged by country and subject
    • Gives references to UST and TIAS numbers
    • Use to verify the existence of a treaty
    • Available for free on the US Department of State website
    • Also offered through Hein Online and WestlawEdge
  • A Guide to U.S. Treaties in Force (1982-present and is used with TIF) (current to 2019)
    • Annual publication
    • Accessed by a combined subject index as well as by numerical and country index
  • Guide to U.S. Treaties in Force: Current Treaty Action Supplement (use with TIF and Guide to U.S. Treaties in Force) (current to 2002)
  • U.S. Treaty Index
    • Currently contains 13 volumes and 5 supplements
    • Replaces, in its entirety, the former UST cumulative indexing service, which began in 1973
    • Beginning with 2001 revised volumes, date coverage expands: 1776-2000 consolidation
    • Consists of master guide (numerical), chronological index, country index, subject index, and geographical subject index
    • Kept up to date by supplements, revised volumes, and Kavass’s Current treaty index
  • Current Treaty Index
    • Cumulative index to the United States slip treaties and agreements, and treaties and agreements not published in TIAS
    • Volumes for 1982- include information on TIAS
    • Issues for 1982-1999 also known as 1st through 24th editions
    • Companion service to The United States Treaty Index: 1776-… consolidation, and its supplements
    • Updates the UST cumulative indexing service
    • Changed to loose-leaf format in 1999. Also available through Hein Online.
  • Index to International Treaties & Agreements
    • This index covers in-force treaties and agreements from 1783 to present
    • Available in electronic format as part of the Oceana Online Web site, TIARA
    • Known as Treaty and International Agreements Online

For treaties to which the US is a party, one should consult one or more of the following to locate information on the treaty’s status, updating a treaty, and ratification of a treaty:

  • TIF available on HeinOnline and Westlaw
  • Guide to TIF
  • CCH Congressional Index available on Congress and Govinfo
  • Current Treaty Index available on Hein Online.
  • Senate Website
  • Shepard’s U.S. Citations. N.B. Pre-1950 treaties are listed by their Statute at Large # and post-1950 treaties are listed by their UST or TIAS #s.
  • Some treaty secretariats have web sites that might provide status info
  • Department of State Office of Treaty Affairs may be able to help (202) 647-1345 or .

Keep in mind that treaties, which have not been ratified, do not necessarily die at the end of a US congressional session – they frequently carry over to subsequent sessions.

5. Multilateral Treaties

The following sources are helpful for locating the text of multilateral treaties:

  • Multilateral Treaties: Index & Current Status (kept up to date by cumulative pamphlet supplements)
  • Multilateral Treaty Calendar 1648-1995 (current to 1995)
  • Status of Multilateral Treaties Deposited with the Secretary General

    • Includes status and reservation information
    • For the texts of these agreements, refer to the United Nations Treaty Series
    • Available in print and electronic formats
    • Print begins in 1959; discontinued in 2010
    • The electronic version is a huge UN database United Nations Treaty Series
    • UN Charter requires member nations to register their bilateral or multilateral treaties with the UN
    • UNTS is still the most complete list
  • Other multilateral treaty series include:
    • League of Nations Treaty Series
    • Organization of American States Treaty Series
    • Pan American Union Treaty Series
    • European Conventions and Agreements (also known as European Treaty Series)

Europe – EU founding treaties available online. Treaties the EU has entered into as a party are also published in the Official Journal of the European Union (OJ), L Series. These are available in electronic form from 1998 to the present. International Legal Materials (ILM) – The ILM has been published since 1962. It is a useful source for draft treaties, new, or unusual treaties. It is available in electronic format on LexisAdvance and WestlawNext. To find the status of a multilateral treaty, a good place to begin is with the Multilateral Treaties Deposited with the Secretary General. This is a print product but is also available online.

Finding the reservations of parties to a multilateral treaty can be a really tough job. Reservations often arise during the ratification process, and so they can be discovered in legislative histories (if any exist). For European treaties, one should consult the European Treaty Series. In the US, reservations can typically be found in the Congressional Record. For other countries, a researcher may need to contact a given country’s diplomatic mission for information about that country’s reservations for a specific treaty.

To learn about the ratification process or status of a treaty, remember that a country may be a signatory but not ratify a treaty. To determine the process of ratification outside the US, there are two main resources:

  • National Treaty Law and Practice (available through HeinOnline)
  • Parliamentary Participation in the Making and Operation of Treaties, a Comparative Study

Most modern multilateral treaties create an administrative body called a secretariat. The secretariat is charged with the administration of the terms of the treaty. Secretariats can be useful sources for information relevant to treaty research. The secretariat is generally charged with:

  • Holding the text of the treaty
  • Tracking signatures
  • Tracking accession and ratification
  • Monitoring compliance

Many secretariats have their own websites with links to important treaty documents and other information.[18] These websites are easily found using a general search engine.

6. Bilateral Treaties – US Not a Party

Researching bilateral treaties where the US is not a party can be very challenging indeed. First of all, every country deals with its bilateral treaties differently.[19] Perhaps the easiest way to find these treaty documents is in a commercial compilation of bilateral treaties by subject or online databases. Examples include

  • Investment Promotion and Protection Treaties (from 1983) (Oceana)
  • Diamond’s International Tax Treaties of All Nations (Oceana) (the original 55-volume set is now available in a searchable electronic format)
  • The World Treaty Index (ceased publication in the late 1980s; begins with the League of Nations Treaty Series and the United Nations Treaty Series).[20]
  • For bilateral treaties between non-U.S. countries and some multilateral treaties, WorldLII International Treaties Collection can be a helpful resource.
  • Also, both U.S. and non-U.S. treaties can be found in EISIL (Electronic Information System for International Law) which is provided through the American Society of International Law (ASIL).[21]

Some government websites publish indexes to treaties or the full texts of treaties. The United Kingdom, Australia, France, and the Netherlands have complete treaty information for those countries. Keep in mind that diplomatic missions of countries can also provide treaty information, so if one is having trouble locating the text of a bilateral treaty to which the United States is not a party, one could contact the official representative(s) of the government in question. A place to find contact information for embassies or consulates is Embassy World.

For treaties to which the US is a party that you cannot find in other sources, you can contact the country desk at the Department of State or Department of Commerce.

7. Electronic Resources for Treaty Research

This guide concludes with a very brief survey of some of the more important electronic resources for treaty research. While we have included links to the electronic platforms for a number of resources listed above, what follows is a listing of materials that did not easily fit into the descriptions or organizational scheme. Electronic access to important legal information of all kinds has increasingly become the norm. This is particularly true with respect to international treaty information. Because of the dynamic nature of the digital world of treaty information, the following section does not pretend to be comprehensive, and we are sure the guide overlooks any number of excellent electronic resources. We strive merely to represent the nature and variety of electronic resources for treaty information.

United Nations and United States treaty sources are perhaps the easiest to find in electronic formats. In fact, it is probably fair to say that the UN is the leader in electronic access.[22] Below is a sampling of several free Internet resources for treaty information. Included in this section are resources for United Nations treaties, United States treaties, and European and Organization of American States treaties. The final section contains information about several subscription or proprietary databases, excluding Lexis and Westlaw.

7.1. Free Internet Resources

United Nations Treaty Collection

  • Huge full text database of UN treaties
  • Many helpful indices and tools
  • Use the help menus!
  • Advanced and Basic search options
  • The advanced search option contains very useful menus of “Title/Keyword of the Agreement,” “Subject,” “Participants,” and other limiting factors.
  • Updated daily.

UN Official Document System

  • Full-text database
  • Search engine retrieves documents only from the UN Documentation database (documents and preliminary versions of UN resolutions)
  • Contains convenient tabs for the General Assembly, Security Council, Economic and Social Committee, Secretariat, International Court of Justice, and the Trustee Council.
  • Simple and advanced search capabilities, including full text search. Full text searches will often result in the most hits.
  • Contains a very helpful link to the Dag Hammerskjöld Library Research Guides. Offers e-subscription feature that will send documents automatically by email or RSS feed.
  • Offers access to the Dag Hammerskjöld Library Reference Team via email and phone.

UN Digital Library – online catalogue of United Nations documents and publications indexed by the Dag Hammarskjőld Library.

  • Includes open access and commercial publications as well as non-UN sources.
  • Goes back to 1979 but expanding to include earlier years regularly
  • Access to some full text documents in Arabic, Chinese, English, French, Russian, and Spanish.

Treaty Research Guide of the Dag Hammarskjőld Library

  • Located on the International Law section of the library’s comprehensive UN Documentation Research Guides.
  • Introduces UN Treaty Collection, Treaty Monitoring Bodies and how to research treaty drafting.

Legal Research Guide of the Library of the UN Office in Geneva

  • Housed on the Law section of the Library’s Research Guide.
  • Incudes a guide to treaty research that provides selected online treaty sources.

World Legal Information Institute

  • Free and non-profit global legal research database developed and updated collaboratively by multiple legal information institutes, including Australasian Legal Information Institute (AustLII), British and Irish Legal Information Institute (BAILII), Canadian Legal Information Institute (CanLII), Hong Kong Legal Information Institute (HKLII), Legal Information Institute (Cornell) (LII (Cornell)), Pacific Islands Legal Information Institute (PacLII), and Wits University School of Law (Wits Law School).
  • Provides a single search platform for legal databases located on participating institutes.
  • Offers International Treaties Collection and country-specific treaty information.

Statutes at Large

  • Permanent collection of laws and resolutions enacted during each session of Congress.
  • Statutes at Large ceased publishing US treaties in 1948.
  • This is a good source for older US/Native American treaties.

US Department of State

  • Limited quantity, but what’s there is free and available in full text
  • Includes Private International Law Database.
  • No quick link to treaties on the home page; use the search function to locate treaties

US Trade Representative

  • Site contains the text of many US trade agreements and treaties
  • Includes global, regional, and bilateral trade agreements and/or links to secretariats, organizations, or other related documentation

Other sites to consider:

ASIL Electronic Resource Guide – Look Guide to Public International Law that includes an instruction to treaty research.

Use or any other search engine to locate treaties. This is the most imprecise method (a broadcast method), and you need to be particularly mindful of the varied quality of the sources you get from this kind of search. A general search for “treaty” on Google currently results in over 56,300,000 hits. Most of these sites are worthless, but some may be quite helpful. Use the advanced search tool to help focus your search.

7.2. Subscription Databases

Access UN

  • Premier index to UN documents, including Official Records, masthead documents, draft resolutions, meeting records, UN Sales Publications, and the UN Treaty Series citations. Also included are the full text records of thousands of UN documents.
  • Permits searching in multiple fields (e.g., subject, country, document number, etc.)
  • You can limit the search to full text documents, or by date ranges
  • The help menu is very helpful indeed.


  • HeinOnline uses a stable, reliable platform.
  • Treaty research resources found primarily in the United Nations Law Collection and the extensive Treaties and Agreements Library, which includes official and unofficial publications as well as guides, indexes, treatises, and books.
  • Contains full text images of several key treaty research tools (e.g., Bevans)
  • Full text documents available only as an image (PDF)
  • Not 100% complete or current, but they’re adding more all the time
  • Not easily searchable; best for KNOWN ITEM searches (i.e., when you have citation)
  • This includes the full text of the Statutes at Large from 1789-2008. HeinOnline is providing electronic access to Indian treaties (1778-1971) and treaties between the U.S. and foreign nations, and treaties and other international agreements.


  • WestlawNext contains treaties in addition to other international materials
  • “International Materials Index” very helpful in navigating treaty sources in WestlawNext
  • Standard Westlaw search features apply


  • Offers treaty-related materials under the “international law” subject area tab.
  • Standard Lexis search features apply

[1] Black’s Law Dictionary, 15c (11th ed. 2009).

[2] Vienna Convention on the Law of Treaties of 1969, art. 2, §1(a) (defining a treaty as “an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation”).

[3] See United Nations Treaty Handbook, Glossary (providing the definition of these treaty-like instruments).

[4] Vienna Convention on the Law of Treaties of 1969, art 34.

[5] U.S. Const. art. II, § 2, Cornell Law School Legal Information Institute.

[6] See International Agreements and U.S. Law, ASIL Insights (1997) (providing a more complete description of the difference between treaties and international agreements).

[7] See United Nations Treaty Collection (describing treaty terms in further detail).

[8] Black’s Law Dictionary, 16c (11th ed. 2019).

[9] Id. at 18c.

[10] See United States Treaty Collection

[11] See International Agreements and U.S. Law, ASIL Insights (1997) (providing a more complete description of the difference between treaties and international agreements).

[12] Black’s Law Dictionary, 1827 (11th ed. 2019).

[13] See United Nations Treaty Handbook, Glossary 69.

[14] Black’s Law Dictionary, 15c (11th ed. 2019).

[15] Id.

[16] Id. at 1866.

[17] See Jonathan Pratter’s excellent guide to travaux preparatoire on GlobaLex.

[18] See, for example the website for the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

[19] Stephanie Weigmann has created a very useful guide for locating treaties where the US is not a party. Her guide can be found at

[20] The site is administered by Glenda Pearson at the University of Washington. According the to the site, The World Treaty Index provides access to over 55,000 treaties of the 20th century, from sources ranging from the United Nations Treaty Series to various national indexes, gazettes, and official files. This site has temporarily resided in the new WTI site since a complete site resign in 2010. The updated page will provide a comprehensive database of over 75,000 treaties in the new WTI site.

[21] The EISIL is temporarily unavailable due to ongoing upgrade to EISIL 2.0.

[22] UN treaty documents are typically found in all six official languages: Arabic, Chinese, English, French, Russian, and Spanish.