Firstly, author talks about the difficulties proofing of the casual link between physicians’ fault and deterioration of the patients’ health or death. He points out the proofing easements, which are approved to suing patient by German courts. Their opinion on moving the burden of proofing of casual link from the appellant to the accused, in the case when the sever faults, is specially explained. In these cases German courts start from the assumption that the causal link between the fault and the damage exists and they admit right of the physician to dispute this assumption. Since the positive result of this disputing is mainly impossible, sever physicians’ fault compensates the uncertainly of the casual link, and that is why the patient gets the total damage compensation (principle ‘all or nothing’).