The evidential problems caused by medical and scientific uncertainty (eg as to the causes of disease in individual cases) have prompted courts in several European jurisdictions to investigate alternatives to their ordinary pproaches to proof of causation. Amongst these is the concept of proportional liability – liability in proportion to the risk attributable to the tortious conduct – which has so far been adopted in Austria, the Netherlands and the UK. Proportional liability is also proposed in the European Group on Tort Law’s Principles of European Tort Law, and the Group has embarked on a dedicated project to further explore the proper scope of the proportional liability approach. On Monday, May 31, 2010 at 8:00 pm in the lecture hall Rechtswissenschaften (Juridicum II), Schenkenstrasse 8-10 1010 Vienna, Ken Oliphant, a member of the Group, will summarise the outcomes of the research so far and offer some personal reflections on the concept of proportional liability. Afterwards Alexander Stremitzer will discuss the overall advantages of proportional liability and will complete his analysis by giving a comparative law overview with special consideration of new US-Jurisprudence in the fields of medical, environmental and capital market law.