Understanding the Elusive Definition of Terrorism in International Law

All nations agree that terrorism must be fought, but they struggle to define it. This confusion has persisted for almost 50 years. Corentin Sire explored this issue in his PhD thesis, supervised by Professors Anthony Amicelle and Thomas Hippler. His findings appear in the journal Penal Field.

Sire began his research in 2016, amidst rising concerns about terrorism. He noted that the term originally came from 18th-century France. It labeled the violent actions of the French Revolution and is inherently subjective.

Terrorism first entered international law discussions at the 1919 Paris Conference, where “systematic terrorism” referred to war crimes against civilians. The League of Nations addressed it more seriously after a 1934 attack in Marseille. Although two conventions included a terrorism definition, they were shelved due to World War II.

After WWII, the United Nations revisited the issue nearly 30 years later. During the 1970s, debates arose linked to decolonization conflicts and the Israeli-Palestinian conflict. Three groups emerged: the Western Bloc wanted quick action, the Non-Aligned Movement sought to distinguish terrorism from liberation movements, and the Eastern Bloc maintained ambiguity. The UN chose a practical route, criminalizing specific violent acts rather than defining terrorism.

The 1990s saw the UN Security Council take the lead in counter-terrorism, listing groups labeled as terrorists. This approach allowed action without consensus on the definition. However, this lack of clarity led to reduced transparency and human rights concerns. After the 2001 September 11 attacks, countries increased counter-terrorism efforts, creating their own strategies and boosting cooperation among national security agencies.

Sire highlighted that powerful nations often shape terrorism definitions. For example, the U.S.-led War on Terror sometimes violated international law under the guise of fighting terrorism. This creates a paradox: the UN, founded on state equality and international law, now deals with a concept that reflects global power imbalances.

Attempts to restore proper international law roles include the 2006 United Nations Global Counter-Terrorism Strategy, which seeks a common approach to counter-terrorism. This strategy is reviewed biennially, and in 2017 the Office of Counter-Terrorism was established within the UN. While these initiatives complicate the UN’s counter-terrorism position, they offer a necessary framework. Though a universal definition remains elusive, the UN aims to prevent counter-terrorism measures from violating fundamental international law principles. However, it struggles to impose restrictions due to state sovereignty concerns.

Sire cautions against using the term terrorism to justify actions. Any act, even the most objectionable, can be excused in the name of combating terrorism.