Abstract Litigation concerning hepatitis B vaccination provides a good illustration of the difficulties courts encounter when deciding on compensation claims in which scientific uncertainty, whether real or perceived, is present. Despite the difference in approach to vaccination - an obligation in France and a recommendation in Germany -, their vaccine coverage is comparable, as are their regimes of compensation for damage attributed to vaccination, whether on the basis of producer liability or national solidarity. Confronted with scientific uncertainty, German and French courts choose to make use of presumptions to establish legal causality that is not contingent on scientific causality. German and French case law diverge however, with regard to their relationship to scientific criteria of causality, the volume of court cases, and consideration of claims, highlighting what seems to be a distinctive situation in France.