Individuals who have travelled from Sweden and affiliated to the Islamic State in Syria will, after the fall of the caliphate, return home to Sweden. The concept of ISIS returnees has begun to dominate the debate and there is a common concern that individuals who possess radicalized opinions should return to Sweden only to commit terrorist crimes. The study is based on a qualitative research method, specifically an interview methodology with semi-structured interviews. The study identifies the capacity Sweden possesses, according to experts, both socially and legally, to deal with the problems of Swedish citizens who wants to return from ISIS-controlled areas. The study also aims to examines measures that is the most suitable to apply to returnees from the expert’s perspective. An analysis based on the Transitional Justice framework identified the importance of applying both legal aspects, as well as social processes in order to handle the problems with returnees. Through a review of previous research, three courts were identified, because they previously had the ability to prosecute individuals who committed criminal acts, these are: The Ad-hoc Tribunal, the Hybrid Court and the International Criminal Court. It was therefore considered important to examine these in order to review whether the courts were a legal alternative in the discussion of returnees who committed terrorist crimes. All actors, both international and national, have lack of capacity and efficiency regarding how to handle the ISIS-returnees. The study therefore contributes to an understanding of the capacity Sweden possesses in order to handle the problem of individuals who are now returning from ISIS, and also proposes new ways to handle the problematic aspects about ISIS-returnees to Sweden.