Uncertain Causation, Loss of a Chance and Proportional Liability in Medical Malpractice Cases

Abstract Proving the causal connection between a medical error and the personal injury suffered by a patient might turn out to be very difficult, if not impossible. If the claimant manages to substantiate that connection by reaching the required degree of probability, they will be fully compensated, and if not, they will not be indemnified at all, even though fault has been established on the part of the medical professional. This ‘all-or-nothing’ approach means that slight differences in the degree of probability (values slightly lower versus values slightly higher than the required threshold) result in fundamental differences in the amount of damages. In order to prevent this unjust outcome and to provide at least partial compensation to those who are unable to demonstrate the existence of a causal link, several legal systems resort to the concept of loss of a chance, which redefines the object of legal protection and regards as recoverable loss the lost or diminished chance of avoiding traditionally understood damage (personal injury). Another proposed alternative to the ‘all-or-nothing’ approach is proportional liability based on potential causation. The present contribution examines the advantages and disadvantages of both concepts and discusses the possibility of their application under Polish law.