The Prosecution of Foreign Fighters in Western Europe: The Difficult Relationship Between Counter-Terrorism and International Humanitarian Law

The collapse of the Caliphate, including the resulting surrender of hundreds of fighters to the Syrian Democratic Forces, as well as the tweets from President Trump threatening his allies to release 800 Islamic State fighters if they would not take back their own citizens, has led to an intense debate on what to do with these so-called foreign fighters. Many counter-terrorism experts and international lawyers have argued that these fighters should be brought home and brought to justice before national courts, for moral, legal and long-term security reasons. In the context of national prosecutions, the aim should be to not have a one-size fits all, but rather a tailored approach, ensuring that perpetrators are prosecuted, as much as possible, for the actual crimes they have committed. If we consider foreign fighters to be individuals joining a non-state armed group in an armed conflict, there is by definition an important nexus between foreign fighters and armed conflict. Hence due regard should also be paid to international humanitarian law in the framework of their prosecution. This article will analyse and assess the first cases where the relationship between counter-terrorism and international humanitarian law played a role and aims to provide, based on the direction this discussion is heading, the necessary guidance.