Assurance de responsabilité et aléa moral dans les régimes de responsabilité objective et pour faute

This paper analyses whether liability insurance is socially desirable, under strict liability or under the negligence rule, when the injurer?s behavior is imperfectly observable. Liability insurance is known to be socially beneficial under the strict liability rule, even though it can reduce incentives to exercise due care in situations characterized by moral hazard. Does this result extend to the negligence rule, when courts obtain only imperfect information about levels of care ? I show that liability insurance may fail to be socially beneficial depending on the size of type I and type II errors in courts? rulings (erroneously finding negligence when the defendant exerted due care vs. not finding negligence when he was careless). I give sufficient conditions on the type I and type II errors for liability insurance to be socially beneficial. I show that these conditions are satisfied if the courts? standard of proof for decision under uncertainty is the "preponderance of the evidence" standard used in common law and some civilian jurisdictions. Classification JEL : D8, K4