International legal implications concerning “foreign terrorist fighters”

In recent years, an increasing number of foreign fighters moved to Iraq and Syria, mainly motivated by the purpose to receive training for planning or committing terrorist acts. This has been a threat to international peace and security both for the State of destination, because of the contribution that foreign fighters make to the radicalization of the conflicts abroad, and for the States of origin, as some may return with the intention of committing violent acts. The article examines the international responses to the challenges posed by this practice by focusing on the activities and initiatives carried out by the Security Council, which adopted a number of resolutions specifically addressing the issue within the framework of the UN Global Counter-Terrorism Strategy. These resolutions impose on States legal obligations as regards the adoption of measures aimed at preventing the flow of foreign terrorist fighters, including the duty to criminalize their conduct. The questions therefore arise as to whether the Security Council acted ultra vires by assuming competence as a legislator, and to which may be the legal implications of the exercise of such power. The first question implies ascertaining whether the resolutions on “foreign terrorist fighters” create new obligations for States without their consent. The premise that international humanitarian law does not provide specific guidance on what status foreign fighters might be entitled to and, consequently, on how they should be treated, raises a further question: to what extent do States of origin and States of transit have a duty under international law to prevent the departure of foreign fighters, or to punish them once they return? The topic is analysed in the light of all the relevant customary and treaty rules of international law. As regards the legal implications of these resolutions, they have been strongly criticized for their potential negative impact on human rights, with special reference to the right to private life and to the principle of legality, given that an international definition of terrorism is lacking. The article analyses whether effective counterterrorism measures and the protection of human rights are to be considered as conflicting goals, or rather as complementary and mutually reinforcing ones.