In several Western countries, conservative religious and political groups are mobilising against sex education programs (France, USA, Canada, Belgium, Switzerland, Germany…). This article, devoted to campaigns in the United States, analyses how these groups are using the weapon of law, i.e. arguments based on respect for fundamental rights (freedom of religion and conscience, the right to educate one's children in accordance with one's convictions, etc.). This article looks at how these moral crusades, which aim to bring about a general conformation of the public sphere, challenge the principle of education for citizenship and sexual democracy.