This policy brief edited by PATRIR examines how the recognition and governance of mass atrocities serve as a critical test of the European Union’s rule-of-law credibility in the European Neighbourhood, particularly in relation to the ongoing war in Gaza. While atrocity prevention, genocide recognition, and cooperation with international justice mechanisms are integral to the EU’s legal and political frameworks, their implementation is increasingly shaped by security exceptionalism and geopolitical selectivity. Drawing on recent conflicts and EU partnerships across the Neighbourhood, this brief demonstrates that inconsistent application of international humanitarian law and transitional-justice conditionality undermines the authority of EU rule-of-law engagement, fosters scepticism among partner societies, and enables authoritarian consolidation. The brief concludes that restoring credibility requires re-anchoring security cooperation within binding atrocity-law obligations, enforceable conditionality, and the protection of democratic dissensus.