International Judicial Monitor
Published by the International judicial Academy of the International Law Institute, Washington, D.C.
with circulation assistance from the American Society of International Law

Spring 2017 Issue


International Law and Crimes of Terrorism

International Law and Crimes of TerrorismBy: Issam M. Saliba, Legal Specialist, Law Library of the United States Congress

In 1937 the League of Nations adopted the first multilateral Convention for the Prevention and Punishment of Terrorism. Article 1 of the Convention defines acts of terrorism as:

Criminal acts directed against a state or intended to create a state of terror in the minds of particular persons, or a group of persons, or the general public.

This Convention was never ratified and never entered into force Attempts to adopt a substitute treaty have long been frustrated since.

The United Nations member states are still unable, for several years now, to move forward on the Draft Comprehensive Terrorism Convention which requires acts of terrorism to be intended “to intimidate a population or to compel a Government or an international organization to do or to abstain from doing any act.”

The main stumbling block against moving forward is the lack of agreement among the states on a clear definition of the elements that constitute terrorism. This is despite a rich repertoire of definitions crafted by distinguished scholars in the field and from other sources.

In United States v. Yousef  the U.S. Second Circuit Court of Appeals ruled in 2003 that terrorism is not an international crime giving rise to universal jurisdiction because there is no “international consensus on the definition of terrorism or even its proscription” Yet a minority view exists to the effect that terrorism has already been defined by international customary law. 

In an article (Journal of Criminal Justice, Multi-Faceted Criminal Notion of Terrorism in International Law) published in 2006 the late Antonio Cassese, a distinguished professor of international law at the University of Florence, wrote:

"Contrary to what many believe, a generally accepted definition of terrorism as an international crime in time of peace does exist.  This definition has evolved in the international community at the level of customary law."

More recently, in 2011 the Special Tribunal for Lebanon or STL, a mixed tribunal established to prosecute a local crime under Lebanese law, issued an opinion in which it concluded that:

A customary rule of international law regarding the international crime of terrorism, at least in time of peace, has indeed emerged.

There should be no surprise that this pronouncement is concordant with Professor Cassese’s opinion.  He, by that time, had become the President of the STL and acted as the Judge Rapporteur who drafted the STL opinion. 

In describing what constitutes the international crime of terrorism the STL identified the following three elements:

  • The perpetration of a criminal act (such as murder, kidnapping, hostage-taking, arson, and so on), or threatening such an act;
  • The intent to spread fear among the population (which would generally entail the creation of public danger) or directly or indirectly coerce a national or international authority to take some action, or to refrain from taking it; and
  • The act involves a transnational element

Taking the STL opinion at its face value, the crime of terrorism should be an international crime and would be by now working its way to be included within the jurisdiction of the International Criminal Court along the crimes against humanity, genocide, war crimes, and the newly added crime of aggression.

A member of the Department of International Law at the Military Advocate General Corps of the Israel

Defense Force cited the STL opinion in his argument for prosecuting terrorists by the International Criminal Court. Despite the STL opinion and its supporters we are still far from being able to use the international criminal law as an effective tool in the fight against terrorism or claim terrorism as an international crime under customary international law.

First, it is probably reasonable to suggest that a rule outlawing all acts of terrorism has emerged in many countries due to:

  1. The many specific anti-terrorism treaties such as the International Convention against the Taking of Hostages, the International Convention for the Suppression of Terrorist Bombings, the International Convention for the Suppression of the Financing of Terrorism, and another 12 or 13 similar conventions; and

  2. The plethora of UN resolutions and pronouncements requiring states to take certain specific actions in matters related to terrorism

But such a rule outlawing terrorism is not sufficient to make terrorism an international crime.  As Kai Ambos and Anina Timmermann of the University of Gottingen in Germany explain in their comments on the STL opinion:

While it is difficult to disagree with the Chamber [meaning the appellate chamber of the STL] as to a (primary) customary rule outlawing terrorism and the ensuing obligations of states in its prevention and suppression, it is a different matter to infer from this prohibition without further ado the existence of a secondary rule in the form of an international crime of terrorism.

Second, it is counterintuitive to assert that an international customary rule defining terrorism has emerged, while United Nations instruments, let alone the opinions of scholars and jurists, are not consistent on this issue. 

In its Declaration on Measures to Eliminate International Terrorism adopted in 1994, and the Supplementary Declaration of 1996, the United Nations General Assembly defines terrorism as:

  • criminal acts,
  • intended or calculated to provoke a state of terror in the general public, a group of persons or particular persons,
  • for political purposes

The International Convention for the Suppression of the Financing of Terrorism of 1999, defines terrorism as:

  • an act
  • intended to cause death or serious bodily injury to a civilian, or to any other person not taking an active part in the hostilities in a situation of armed conflict,
  • when the purpose of such act, by its nature or context, is to intimidate a population, or to compel a government or an international organization to do or to abstain from doing any act.

It is clear that these two definitions differ from each other and from the definition offered by the STL notwithstanding that some elements are common in all three definitions. 

Third, regardless of what definition is adopted or agreed upon terrorism appears to be evolving and changing at a rapid pace.  I wonder, for example, whether any definition would be able to capture all the acts that the civilized world considers as being acts of terrorism. Let us take the killing of Christians and Azidis who refuse to convert or pay the jiziah as demanded by the Islamic State (ISIS.)  Would such killings be covered in any of the foregoing definitions if the real motive behind the killing was the distorted belief of the killers that their actions are required by the command of God?

Note: This article expresses the author’s personal opinions and do not reflect the views of the Library of Congress or any other U.S. Government institution.

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with assistance from the American Society of International Law.

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