Der Einwand rechtmäßigen Alternativverhaltens – Rechtsvergleich, ökonomische Analyse und Implikationen für die Proportionalhaftung -

The Doctrine of »rechtmäßiges Alternativverhalten« – A Comparative and Economic Approach and its Implications for Proportional Liability The German doctrine of »rechtmäßiges Alternativverhalten« is a defence which allows the tortfeasor to steer clear of any compensatory claim for harm that would have still occurred even if he had exercised due care. A comparative analysis reveals that this doctrine and its equivalent in Common Law, where it is often viewed as an issue of causation, are recognised across jurisdictions. Its purpose is to prevent over-compensation. From an economic perspective, over-compensation can be shown to be harmful in a negligence-based liability system if court decisions are likely to be imprecise due to difficulties in fact-finding. Hence, under this very realistic scenario, the doctrine plays an important efficiency role by improving the quality of negligence-based liability rules. However, the defence and its functional equivalents in the Common Law are not generally recognised by courts if the hypothetical course of action under due care is uncertain. This is because, under standard rules of proof, the court would often have to rule against the plaintiff if the latter could not establish up to a certain probability threshold that the defendant's deviation from due care had caused the harm. In such a case the courts often rule against the defendant, effectively ignoring the defence. This reintroduces the identified inefficiencies stemming from over-compensation. Assessing liability proportional to the probability that harm was caused by the defendant can be shown to solve this problem. Moreover, this article argues that the application of the proportional liability rule also has a strong doctrinal appeal. In fact, this very rule stems from the consistent application of the doctrine of »rechtmäßiges Alternativverhalten« and the causation requirement in situations of uncertainty.