This Policy Brief aims to inform the current debate on integrating rehabilitation into the overall approach to foreign fighters by highlighting the challenges and opportunities within the criminal justice sector response to the phenomenon. The authors first analyse the specifics of the contemporary foreign fighter phenomenon and the criminal justice sector response in the EU. Second, the Policy Brief outlines the main contours of rehabilitation programmes for violent extremist offenders and the benefits of rehabilitation in this particular foreign fighter context. Third, the authors explore the challenges and opportunities at four stages of the criminal justice sector chain for incorporating rehabilitation, namely the pre-trial, trial and sentencing phase, as well as during incarceration and beyond the prison context. The final section offers reflections and recommendations to incorporate rehabilitation into the criminal justice sector response in dealing with foreign fighters.