The international jurisprudential challenge of the concept of terrorism and the role of Customary International Law as a potential provider of a legal definition

For almost a century, international legal scholars have been trying to agree upon a unified, legal definition of the concept of “terrorism”.

Multiple conflicting definitions have emerged in the practice of the UN General Assembly and the Security Council, in national case law and legislation. While there is a definite movement towards generic definition over time, the divergent approaches to a definition, and persistent disagreement mainly grounded in political disputes, have inhibited the formal legal consensus of such an agreement. At best, there is an international consensus on condemning terrorism and a widespread support for a general prohibition, but insufficiently precise to support an individual criminal liability, not conflicting the principle of legality, (nulla poena sine lege), recognized as a peremptory norm of international law, (enshrined both in Article 15 of the International Covenant on Civil and Political Rights (CCPR) and Article 7 in the European Convention on Human Rights art 7.

Regardless of the lack of a textual definition in hard law, is it still possible to demonstrate that there is a specific, developed, international definition of terrorism as a concept? A definition based on international customary law? Does it exist an accepted definition based on soft law sources? In my thesis, I will try to provide a deeper comprehension of and elaborate in more detail on these questions.

The methodological approach:

Within the scope of methodology, I believe that the judicial positivistic school of international law[1] describes best the abstract legal theory that I am applying in my thesis. The more modern version of this legal methodology gives more room for elaborating on customary law. And this is where I am circling the core of my thesis.

Within a judicial positivistic school of international law, there will be a relatively clear distinction between de lege lata and de lege ferenda debate. For my project, this is positive because I am analyzing UN treaties, conventions, international and national court practice and other legal sources which belongs to a doctrinal legal research. The specific methodology I am intending to use would perhaps most accurately be described as doctrinal analyses of legal texts, meaning that I will apply primary legal sources and relevant international laws/conventions/ statutes combined and try to interpret and balance them against each other. I need to examine carefully international case law as a reference for the legal sources and research the contradictions between customary law and an international agreement/ protocol where the latter is binding only amongst the states who declare such.

In addition to the doctrinal focal point, the methodology of the thesis will also include certain elements of comparison. Several international protocols/statutes are considered as declarations of international customary law, and in my research, I intend to assess whether we gradually are facing a change of the international jurisdiction, concerning terrorism, based on national states initiatives to implement perceived international customary law in the domestic laws.

Cambridge University, 28 February 2022

Tove Wulff Nilsen

PhD Candidate, UIT, Faculty of Law.

[1] Legal positivism is the thesis that the existence and content of law depend on social facts and not on its merits. The English jurist John Austin (1790–1859) formulated it the following way: The existence of law is one thing; its merit and demerit another. Whether it be or be not is one enquiry; whether it be or be not conformable to an assumed standard, is a different enquiry. (1832 [1995: 157])



Tove Wulff Nilsen (Principal investigator)