This paper focuses on states’ attempts to outlaw the denial of historical facts and the impact that this can have upon expressive freedoms. It compares the prohibition of the denial of the Rwandan genocide with the prohibition of the denial of crimes against humanity in Europe. It also discusses the obligatory forgetfulness imposed in Ancient Athens after the in 401 B.C. In Rwanda, the government has forbidden the denial of the 1994 genocide to legitimize its authority. In Europe, bans on denying the holocaust are dictated by irrational elements in the collective consciousness: a feeling of guilt. In Ancient Athens, the democrats imposed forgetting past misfortunes, a wilful amnesia. Rwanda and other European states impose obligatory remembrance. Ancient Athens instituted forgetfulness. All of these attempts are based on a wrongful use of government power. They are close to imposing official versions of the truth and can have detrimental consequences upon expressive freedoms.