This study introduces the novel concept of the justice/participation paradox to post-conflict peace and justice literature. The 2016 peace agreement between the Colombian government and the Revolutionary Armed Forces of Colombia (FARC) formalised a solution to the peace-versus-justice dilemma: allocating congressional seats to FARC while ensuring legal accountability through the Special Jurisdiction for Peace (JEP). In the JEP, perpetrators receive alternative sanctions instead of prison, provided they fully disclose the truth about their crimes, without inhibiting political participation. This has given rise to a new paradox: the ‘justice/participation paradox’ of promoting a political project in one arena while confessing crimes in another. The article analyses the performativity of confession vis-à-vis political participation, based on 38 interviews, participant observation, and 35 hours of video recording. It finds that former FARC members use the JEP to confess and show remorse while asserting political authority. Their dual role complicates continued political engagement, especially as guaranteed congressional seats expire and JEP sanctions must be fulfilled. Based on these findings, the article underscores the importance of recognising time and grass-roots political participation in future peace processes.