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Program on International Law and Armed Conflict

Research guide for Harvard Law School's research program on international humanitarian law and the law of armed conflict.


About this Guide

This is a research guide for the Harvard Law School Program on International Law and Armed Conflict (PILAC). It provides information about helpful resources for the program's research and work.

Research Librarian Jennifer Allison, who is the Harvard Law Library's PILAC liaison, created and maintains this guide. 

PILAC Training Class

Click the PDF icon above to access the PowerPoint from Jennifer's training class on October 20, 2014.

The class covered these topics:

  • Asking questions and creating a research outline
  • "Smart" Googling to compile initial information
  • Searching specific sites, like, for information about the topic using the keywords you have learned
  • Building a bibliography of relevant scholarly articles, using Google Scholar, Hollis+, and legal periodical indexes like LegalTrac
  • Researching primary sources, including treaties and customary law

Help from a Librarian

For help, visit the HLSL Ask a Librarian website:  

This site includes links to all of our research guides, contact information for the research librarians (phone, text, email, chat), and a schedule of our training classes.  

Guiding Principles

Guiding Principles

This section discusses guiding principles with which PILAC is concerned. It provides definitions, quick links to web resources and articles, and references to books that provide more in-depth discussions of the topics.

International Humanitarian Law

International Humanitarian Law (IHL)

International Humanitarian Law (IHL) creates legal restrictions on waging warfare for the purpose of protecting non-participants. It is comprised of international treaties and customary law.

Jus in Bello is the body of legal norms that regulate the conduct of participants in armed conflict.

The International Committee of the Red Cross (ICRC) provides humanitarian protection of and assistance to people impacted by war and armed conflict. In addition to its work on the ground, the ICRC also provides resources for IHL research.

International Committee of the Red Cross (ICRC) definition:
"International Humanitarian Law is a set of rules which seek, for humanitarian reasons, to limit the effects of armed conflict. It protects persons who are not or are no longer participating in the hostilities and restricts the means and methods of warfare."


Exploring IHL: Additional Sources

Jus ad Bellum and Jus in Bello

Jus ad Bellum and Jus in Bello: Introduction

Jus ad Bellum governs the pre-engagement conduct of states and non-state actors that are considering whether to engage in war and armed conflict.  It is concerned with the justification of and limits to the use of force.

Jus in Bello is the body of legal norms governing battle and occupation - the "conduct of individuals and units toward combatants, non-combatants, property, and the environment." Violations are punishable under customary international law and international legal instruments.

Source: Bouvier Law Dictionary

In scholarly literature, Jus ad Bellum and Jus in Bello are often discussed together. They may be discussed under broader philosophical, religious, or moral principles using the terms Just War Theory or Just War Doctrine (Jus Bellum Iustum). Sometimes these are discussed in combination with a third principle, Jus Post Bellum, which encompasses post-conflict legal norms.

Exploring Jus ad Bellum and Jus in Bello

Geneva Conventions Research


Harvard's Library Catalog: HOLLIS

Use the Harvard Libraries' HOLLIS library catalog to search for books, book chapters, articles (from scholarly journals to newspapers and magazines), internet sources, and other types of materials in the Harvard Libraries' collections.

Maximize your HOLLIS searching experience as follows:

  1. Always sign in with your HUID credentials to save your searches and search results. If you are off campus, this will ensure you see everything, including subscription database content.
  2. Limit your search results using the options on the right side of the search results screen.
  3. Use the Advanced Search option to search specific data fields, including title, author, Library of Congress subject heading, ISBN, and others.

Questions about using HOLLIS? Check out the Hollis FAQs and Quick Tips, or contact the law library's research librarians.

Library of Congress Subject Headings

Library of Congress Subject Headings

Library of Congress (LC) subject headings are a controlled vocabulary of subjects used by the Harvard Library catalogers to categorize library materials. They can be useful for finding multiple sources on the same topic, especially sources in languages other than English, where keywords may not be sufficiently precise.

The Library of Congress has a very helpful and brief explanation of how to search a library catalog using LC subject headings. In addition to outlining the principles of subject headings, it offers four excellent suggestions for finding the appropriate subject headings for your search.

Throughout this guide, there are links to pre-populated searches of HOLLIS, the online catalog of the Harvard Libraries, using relevant LC subject heading keywords.  


ICRC IHL Bibliography

Book Series

Book Series

Some publishers offer series of works that discuss topics relevant to war, armed conflict, and international humanitarian law research.  Click a series link below to view a list of the series titles in the Harvard Libraries collection.



Masters theses and PhD dissertations provide book-length information on topics of interest to PILAC and bibliographies of relevant research materials. 



Harvard affiliates can click the journal titles below for information about print and electronic access to them. Journal website links are also provided; some include free content.

Journal Indexes and Directories


Introduction: Topics

This section of the guide presents topic-specific materials for PILAC research projects.   

It is impossible to list every book and article on every topic in a research guide.  Accordingly, each tab shows a few resources related to the stated topic, selected according to these guidelines:

  • In general, only recent (post-2010) materials are included. These will cite older seminal works, so review their citations and references carefully.
  • When possible, links are to final published articles (not drafts or working versions).

For additional resources, make sure you also look at:


Asymmetric Warfare

Belligerent Occupation

Direct Participation in Hostilities

Introduction: Direct Participation in Hostilities

According to the ICRC, in modern combat, "[c]ivilians have been increasingly involved in activities more closely related to the conduct of hostilities, thus blurring the distinction between civilian and military functions. This has created uncertainty as to how the principle of distinction, the very cornerstone of IHL, should be implemented in the reality of contemporary military operations." 

For more information on this topic, see the ICRC's Direct Participation in Hostilities homepage.

To find materials in the Harvard Library collections on this topic, click the link to the HOLLIS search below:

HOLLIS search: Subject = "Combatants and Noncombatants (International Law)"

Drones and Robots

Drones and Robots: Introduction

The use of drones in war and armed conflict also falls under several broader topics covered in this section of the guide, including asymmetrical warfare, evolving nature of warfare, and extraterritorial use of lethal force. However, there has been a significant amount scholarship generated in the last few years specifically discussing legal issues surrounding the use of drones, robots, and other unmanned devices in armed conflict situations.

Evolving Nature of Warfare

Extraterritorial Use of Lethal Force

Extraterritorial Use of Lethal Force

This broad topic covers multiple concepts, including targeted killings, extraterritorial self-defense (anticipatory/preemptive and otherwise), and state-sponsored acts of extraterritorial terrorism.

Goals of War / War's End

International Tribunals

Medical Assistance

Non-International Armed Conflicts

Non-International Armed Conflicts: Introduction and HOLLIS Library Catalog Searches

According to the ICRC, a "non-international armed conflict" (NIAC) are those conflicts "between governmental forces and non-governmental armed groups, or between such groups only." Specific characteristics of an NIAC are further defined in the ICRC Opinion Paper on Armed Conflict (PDF).

State Responsibility & Practice

Helpful Information for Research

Helpful Information

This section includes links to additional materials that may be helpful for the research conducted by PILAC, such as relevant blogs, other institutes involved in similar work, and IHL scholars. If your research involves United Nations documents and materials, check out the links in this section to the UN Library's research guides.

To suggest additional topics for this section of the guide, please contact Jennifer.





Includes online data aggregator services for armed conflict data.

About War & Armed Conflict Data

Check out these resources for additional information about war and armed conflict datasets and using them for your research.

Digital Document Collections

Digital Document Collections

This section lists miscellaneous collections of digitized documents that may be useful for PILAC research projects.

Institutes, Programs, and Organizations

Institutes, Programs, and Organizations

News Compilations

News Compilations

Peace Palace Library Materials

Peace Palace Library Materials

The Peace Palace Library provides research support and services for Peace Palace institutions, including the International Court of Justice, the Permanent Court of Arbitration, and the Hague Academy of International Law.

The library has created an extensive collection of research guides, including several that discuss war, peace, and security (shown below, click the graphic to go directly to this page).

Screenshot of Peace Palace Library Home Page

PILAC-Created Resources

PILAC-Created Resources

Reference Materials



Other Reference Materials

Related Harvard Law Library Research Guides


IHL and Armed Conflict Law Scholars

Below is a list of scholars and academics who teach and research IHL and armed conflict law.  Links to websites with biographical information and, when available, bibliographies are provided.

Treaty Materials

Treaty Materials - Books

Treaty Materials - Internet

Travaux Préparatoires

The documentary history of the preparation of an international agreement is generally known as its Travaux Préparatoires. The resources below can be helpful in finding these materials for international treaties and agreements.

United Nations Materials

United Nations Organizations

United Nations Research Guides

The UN's Dag Hammarskjöld Library's online research guides are helpful for research involving UN documents and materials. Some of the more relevant of these guides to PILAC's research activities include the following:

Other UN Materials

Harvard Law Library Materials

U.S. Naval War College Materials

U.S. Naval War College: Stockton e-portal

The Stockton e-Portal is a research resource for armed conflict law.  It is maintained by Sasha Radin, diector of research at the U.S. Naval War College Stockton Center for the Sutdy of International Law.


Screenshot of Stockton e-Portal on U.S. Naval War College website



Getting Help

For help, visit the HLSL Ask a Librarian website:  

This site includes links to all of our research guides, contact information for the research librarians (phone, text, email, chat), and a schedule of our training classes.  

You may also contact Jennifer directly (contact information is at the top of this page).

Subject Guide

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Jennifer Allison