An Introduction to Sources for Treaty Research

By Mark Engsberg and Isa Elfers

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 the head of reference. Professor Engsberg is active in professional legal and law librarianship organizations. From 2005 to 2022, he served as editor-in-chief of the International Journal of Legal Information, published by the International Association of Law Libraries (IALL). He became president of IALL in 2022 and recently began serving his second three-year term in that role. 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.

Isa Elfers is a Law Librarian for Research Services at the Hugh F. MacMillan Law Library at Emory University School of Law. She holds an M.L.I.S. from Louisiana State University, a J.D. from the University of California College of Law, San Francisco (UC Law SF, formerly UC Hastings), and a B.A. in literature and creative writing from the University of California, San Diego (UCSD).

Published January/February 2026

(Previously updated by Mark Engsberg and Mary Beth Chappell Lyles in October 2011 and in March 2016; by Mark Engsberg and Kwanghyuk (David) Yoo in May/June 2021)

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, how to locate treaties, how to find aid 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 an “agreement formally signed, ratified, or adhered to between two countries 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, and 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 préparatoires (unless the US is a party and you are 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 eight-to-ten-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 five to six 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 Westlaw Advantage
  • A Guide to U.S. Treaties in Force (1982-present and is used with TIF) (current to 2023)
    • 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 thirteen volumes and five 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 a 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.

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 ratifying a treaty:

  • TIF is available on HeinOnline and Westlaw
  • Guide to TIF
  • CCH Congressional Index available on Congress and GovInfo
  • Current Treaty Index is 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. Available on Lexis+.
  • 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 treatyoffice@state.gov.

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:

Europe — EU founding treaties is available online. Access to all other EU treaties are available via Eur-Lex. EU treaties are published in the Official Journal (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 Hein Online and JSTOR with a two to three year moving wall for full-text publications, as well as on Lexis+ and Westlaw Advantage.

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 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 Hein Online)
  • 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:

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 several 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.[20] Below is a sample 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 Hammarskjöld Library Research Guides.
  • Offers e-subscription feature that will send documents automatically by email or RSS feed.
  • Offers access to the Dag Hammarskjöld Library Reference Team via email and phone.

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

Library of Congress 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 instructions to treaty research.

Use Google 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

UN Digital Library

  • It is the official online catalog and repository for UN documents and publications, including the Official Records, masthead documents, draft resolutions, meeting records, voting records, and speeches. It permits basic, advanced, or authority searches. It provides access to robust metadata. Results can be limited by date, authoring body, draft of final document, and several other facets.
  • UN Sales Publications are available via the UN iLibrary.
  • The UN Treaty Series offers access to UN treaties and depository documents.

Hein Online

  • Hein Online uses a stable, reliable platform.
  • Treaty research resources found primarily in the United Nations Law Collection and the extensive U.S. 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 are 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 1789-2021. Public and Private Laws from 2011-2025, which have not yet been added to the Statutes at Large, are also available.
  • Hein Online provides electronic access to Indian treaties (1778-1971), treaties between the U.S. and foreign nations, and international agreements.

Westlaw Advantage

  • Westlaw Advantage contains treaties in addition to other international materials
  • “International Materials Index” (link leads to Westlaw list which is behind paywall) very helpful in navigating treaty sources in Westlaw Advantage
  • Standard Westlaw search features apply

Lexis+

  • Offers treaty-related materials under the “international law” (link leads to Lexis list which is behind paywall) subject area tab.
  • Standard Lexis search features apply

[1] Black’s Law Dictionary, 15c (12th ed. 2024).

[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 (12th ed. 2024).

[9] Id. at 18c.

[10] See United Nations 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 (12th ed. 2024).

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

[14] Black’s Law Dictionary, 15c (12th ed. 2024).

[15] Id.

[16] Id. at 1866.

[17] See Jonathan Pratter’s excellent guide to travaux préparatoires 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 Weigman has created a very useful guide for locating treaties where the US is not a party. Her guide can be found on LLRX.com.

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