The doctrine of loss of a chance has been deployed by courts jurisdictions in cases presenting causal uncertainty for over a century. In both the civil and common law jurisdictions where it is applied, however, there is debate as to the precise rationale and scope of application of the doctrine. In this working paper we compare theories, cases and practices from four Western European jurisdictions: France, Belgium, the Netherlands and England & Wales. Our methodology departs from a more traditional institutional comparison. [---]