This book examines the criminalisation of denials of genocide and of other mass atrocities in Europe and discusses the implications of protecting institutional historical memory through criminal law. The analysis highlights the tensions with free speech, investigating the relationship between criminal law and historical memory. The book paves the way for a broader discussion about fake news, 'post-truth' scenarios, and free expression in a digital world. The author underscores the need to protect well-founded factual records from the dangers of misinformation. Historical denialism and the related jurisprudence represent a key step in exploring this complex field. The book combines an interdisciplinary approach with criminal law methodology.