Vaccination against hepatitis B has been available since 1982 and is strongly recommended by most health professionals. In France, the hepatitis B vaccine is very widespread, but it has come under suspicion that it can cause demyelinating diseases such as multiple sclerosis. Several epidemiological studies have been carried out to discover if there is indeed a connection between the hepatitis B vaccination and demyelinating diseases, but no such connection has been established so far. Many cases have nevertheless been brought before French courts, in which plaintiffs argue that they have developed a demyelinating disease due to the hepatitis B vaccination, and claim damages either from the State or from hepatitis B vaccine producers.

French courts have been surprisingly favorable to such claims. They have accepted that causation between the hepatitis B vaccination and the plaintiff’s disease could be established on a case-by-case basis, despite the state of scientific uncertainty regarding the possible side effects of this vaccination.

This article presents the context in which litigation about the hepatitis B vaccination has emerged in France and how it has developed. It goes on to explain what positions French courts have adopted and how the latter have managed to bypass scientific uncertainty. It finally offers a critical assessment of the state of French law, focusing on its conceptual shortcomings on the issue of causation as well as on the argumentative flaws in the justifications given by French courts for their position.