Cambridge University Press, December 2017

The Leuven Manual project was notably inspired by the 1994 San Remo Manual on international law applicable to armed conflicts at sea, the 2010 HPCR Manual on international law applicable to air and missile warfare, the 2013 Tallinn Manual on the international law applicable to cyber warfare, and the Tallinn Manual 2.0 on the international law applicable to cyber operations. Just like these manuals, the Leuven Manual is also intended to serve both practitioners and academics.

The Leuven Manual covers “consensual” Peace Operations, both of the traditional peacekeeping variety and of multi-dimensional Peace Operations which include aspects of peacekeeping and peacebuilding, and support for the political process of conflict resolution. Such Peace Operations are based on three bedrock principles: consent of the parties, impartiality and limited use of force. These three principles have evolved along with the evolution of complex multi-dimensional mandates and increasingly volatile operating environments.

The Manual devotes attention to the various stages of the planning and conduct of Peace Operations conducted by both the United Nations (UN) and by regional organizations and other arrangements. It attempts to address all relevant issues, with a particular focus on those which required further research and clarification in doctrine, and where useful or necessary it offers policy recommendations, notably where the law is silent or unclear.

Its authority rests in its bringing the relevant law and associated good practices together in a structured and accessible form of rules to which all contributors (forming the Group of Experts) have subscribed.

The Manual consists of “black letter rules” (145 in total) and an accompanying “commentary”. The black letter rules reflecting existing law are phrased so as to reflect legal obligation and use wordings such as ‘shall’, ‘must’ or ‘have to’… Best practices as reflected in the black letter rules are phrased in conformity with applicable law but are distinguished from positive legal obligations by use of appropriate language such as ‘should’ rather than ‘shall’. The commentary devotes attention to the application and interpretation of the black letter rules.

Over the years, the project to draft the Leuven Manual generated academic activities across the globe: A Group of Experts and Observers (see annex 1) discussed the international law applicable to Peace Operations notably at events in Belgium, Cameroon, Canada, China, the Czech Republic, Germany, Italy and Peru. Observers from the UN’s Office of Legal Affairs and the Department of Peace Operations (formerly DPKO, now DPO), from the ICRC, from the African Union and from NATO participated in the many discussions during the drafting of the black letter rules and commentary. They were given the opportunity to provide specific comments and input on matters related to the policies and practice of their respective organizations, some of which are included as appendices to the Manual. The European Union did not formally designate an Observer to the project, but EU expertise was available thanks to the participation in a personal capacity of Dr. Frederik NAERT (of the Legal Service of the Council of the EU). Furthermore, the project could count on the participation of the Director of the European Security and Defence College, Mr Dirk DUBOIS, a member of the project’s Advisory Board.

The Leuven Manual project was financed by the Society and the Manual is a product of the Society. The Leuven Manual was endorsed by the Society’s Boards on the occasion of their 2017 meetings in Stockholm.

The project was managed by a Project Management Team, headed by the Society’s Assistant Secretary-General, Mr. Alfons VANHEUSDEN. The project’s Senior Academic Advisors were Dr. Dieter FLECK, Professor Terry GILL, and Air Commodore (ret.) Dr. William H. BOOTHBY, three well-known scholars. They acted in the capacity of General Editors of the Manual, along with Mr. VANHEUSDEN, and they ensured the overall quality and cohesion of the Leuven Manual, provided input concerning the structure of the Manual, and participated in the drafting of rules and commentary. Mr. Marco BENATAR and Mr. Remy JORRITSMA supported the project, notably as members of the Project Management Team and as Assistant Editors.

The Project Management Team and Senior Academic Advisors requested selected experts to form the project’s Group of Experts. These contributors were responsible for submitting pieces of publishable quality within the agreed time limits and framework set by the project plan.

The Group of Experts was supplemented by the Advisory Board. This Advisory Board provided viewpoints and offered its advice on best practices.

Support was provided by many governments and institutions by covering the costs of their participating experts or hosting project-related meetings. Their support is acknowledged in the Leuven Manual (see annex 2).

The Leuven Manual has been sent to the leadership of the UN, the EU, NATO, the AU and the ICRC. Furthermore, it has been sent or given to other authorities, organizations etc., including at the national level.

In February 2018, the Society launched the Leuven Manual in New York, in the presence of the UN Undersecretaries-General for Legal Affairs, for Peace Operations (formerly ‘Peacekeeping Operations’), and for Operational Support (formerly ‘Field Support’).

Another event about the Leuven Manual took place at the Geneva Centre for Security Policy (GCSP) on 11 May 2018, for the international community present in Geneva.

In March 2018, the Manual was also presented in Lviv to a Ukrainian audience, including the Ukrainian military, as well as to the ‘Africa Military Law Forum’ convened in Oberammergau with support of US EUCOM.

At the end of October 2018, Professor GILL presented the Leuven Manual to an Italian audience in Taranto at an event organized by the Italian Group of the Society.

In November 2018, a special event on the Leuven Manual took place at NATO’s new Headquarters in Brussels, and later that month Assistant Editor Remy JORRITSMA presented the Leuven Manual in Cameroon’s capital, Yaoundé for an African audience.

In June 2019, the Leuven Manual was presented in Seoul on the occasion of the 10th International Symposium on Security and Military Law, organized for an international audience by the Office of the Judge Advocate General of the ROK Army.

Many of the Leuven Manual’s chapters have been discussed at recent activities of the International Society for Military Law and the Law of War. Participants received the Leuven Manual as part of their conference package at the Congress in Lisbon in May 2018; at the second ‘Silent Leges Inter Arma?’ Conference held in Bruges last September; and at the Dublin conference co-organized in November with the Irish Group of the International Society for Military Law and the Law of War, the Defence Forces Ireland, and the Irish Centre for Human Rights. The Leuven Manual featured also on the Agenda of the 12th Seminar for Legal Advisors of the Armed Forces, hosted by GCSP in June 2019.

In May 2019, the International Review of the Red Cross published a book review written by Mr. Tobias VESTNER and Mr. Alessandro Mario AMOROSO on the Leuven Manual. According to VESTNER and AMOROSO “… there is no other contribution that has taken up the challenge of collecting, analyzing and restating the entire body of law applicable to peace operations. The Manual has therefore at least as much merit as comparable projects realized in other areas of international law, notably the San Remo Manuals, the HPCR Manual and the Tallinn Manual. The choice to supplement the restatement of existing law with best practices in the form of policy recommendations goes even beyond the book’s main purpose and will hopefully contribute to the settling and development of law by practice.”

In the Oxford Bibliographies on normative aspects of international peacekeeping published in October 2018, Professor Boris KONDOCH calls the Leuven Manual The most comprehensive overview and detailed commentary on legal rules applicable to peace operations conducted by the UN, the EU, the North Atlantic Treaty Organization (NATO), the AU, and other organizations. Written by leading scholars and practitioners”.

The Society is currently preparing a scenario-based training package referencing the Leuven Manual.

In order to reach the widest possible readership translation of the Leuven Manual into other UN languages is envisaged. Mrs. Laurence DE GRAEVE coordinated the work on the French version of the Manual, which was published in March 2021.

The Society is also exploring new themes that could be included in a future second edition of the Leuven Manual: In Bruges we discussed the protection of the environment in peace operations, and in Dublin we discussed the protection of personal data in peace operations. Indeed, the Leuven Manual is intended to be a living reference work. This means that the Society envisages a second edition at some stage, that a Group of Experts will update it regularly as appropriate and feasible, and that the Society is already making use of academic events to explore themes that could be added to the Leuven Manual someday. In other words, the Leuven Manual is here to stay.

As stated in the Leuven Manual, all revenues derived from the publication of the Manual will be used in furtherance of the objectives of the Society, with priority given to Manual-related activities. Please note also that all office holders of the Society do their work pro bono. They do not receive any salary or other financial compensation for their work for the organization. The same holds true for all contributors to the Leuven Manual.

The Manual is made up of 21 chapters. None of these chapters is the result of the exclusive work of one contributor as the Group of Experts jointly worked on all chapters. The book discusses:

– The bedrock principles of Peace Operations
– The history of Peace Operations
– The nature and role of the Mandate of a Peace Operation
– The specific legal framework and procedures applicable in
operations of the United Nations, the African Union, the European
Union, NATO and sub-regional organizations
– The Applicability of International Human Rights Law
– The Applicability of International Humanitarian Law
– The Gender perspective
– The Status of Forces and Status of Mission
– Host State Law
– Sending State Law
– Troop Contributing Country MOUs and other instruments and
– The use of force
– Detention
– The Protection of Civilians
– The Aerial and Maritime Dimensions of Peace Operations
– Conduct and discipline
– The promotion of the Rule of Law
– Demining and removal of explosive remnants
– Accountability and responsibility
– Third party claims
– Individual criminal responsibility and international criminal justice
in relation to Peace Operations

See annex 3 for a detailed overview.


Humanitarian Law