Laws and Norms: Experimental Evidence with Liability Rules

International audienceWe conduct an experiment where participants choose between actions that provide private benefits but may also impose losses on others. Three legal environments are compared: no law, strict liability for harm caused to third parties, and an efficiently designed negligence rule where damages are paid only when the harmful action generates a net social loss. Legal obligations are either perfectly enforced (Severe Law) or only weakly so (Mild Law), i.e., expected sanctions are then nondeterrent. We find that behavior can be rationalized in terms of individuals trading-off private benefits, net of legal liability, against the net uncompensated losses caused to others. The weight associated with non-incentivized efficiency concerns is increased by the introduction of a liability rule, whether deterrent or not, and there is evidence that the effect is stronger under strict liability than under the negligence rule