Reasons for the joint use of ex ante regulation and ex post liability to cope with environmental accidents have been a longstanding issue in law and economics literature. This article, which includes the first empirical study of the French environmental legal system, analyzes courts’ decisions when injurers complied with regulatory standards. The results support a general trend toward a clear division of labour between regulation and liability: when both are jointly used, liability encourages aspects of care that are difficult to regulate, especially human behaviour and organization within dangerous entities. An unexpected effect of liability is observed: judges are more severe with the most regulated firms and public agents compared to smaller, private actors. This might be interpreted as complementing regulation when enforcement of regulatory standards is thought to be weak.