Sentencing terrorist leaders and their followers: Evidence from Islamic State defendants in U.S. Federal courts, 2014–2024

Hundreds of leaders and followers of violent extremist organisations have been prosecuted and sentenced in U.S. federal courts. But case outcomes vary widely. In this study, we argue that leaders may receive more severe sentences than followers through three unique, non-compacting mechanisms: proportional accountability, headhunting, and/or deterrence. Evidence comes from a mixed-method study, based on original data collected from court documents associated with over 200 Islamic State-affiliated defendants in U.S. federal courts from 2014 to 2024. We find a discernible ‘leader effect’, which is substantiated by a content analysis of these documents. The results carry implications for theory and practice.