Criminalising terrorist offences and the phenomenon of foreign terrorist fighters at the municipal level without defining terrorism in international law: Does the trick really work?

Although terrorism does not represent a new concern, it keeps evolving and posing new challenges to both the international community and individual States. The efforts to adopt uniform and concerted actions, also in terms of new legal instruments, so far have produced varying and in some instances questionable results. One of the main issues is represented by the lack of a universally agreed-upon definition of terrorism, an issue that resonates also at the domestic level whenever States are called to implement further layers of the existing international counter-terrorism framework. The present article aims at discussing the problems that States face while adopting and enforcing international obligations to criminalise terrorist offences; most recently those connected to the foreign terrorist fighters (ftf s) phenomenon. This article will focus on Italy and it will analyse how the international norms to fight terrorism have been transposed in its domestic legislation and interpreted by its courts.