Scope of liability: the vanishing distinction between negligence and strict liability

The duty-of-care requirement cannot be used anymore as the touchstone to differentiate negligence from strict liability because it can be found in many forms of the latter. Duty of care is smuggled into strict liability hidden under the scope of liability requirement (traditionally called “proximate causation”). As far as the scope of liability requirement is common to negligence and to many forms of strict liability, there is a fairly large common ground to both liability rules, and consequently the marginal Hand formula is applied to both rules. Indeed, under a negligence rule, the marginal Hand formula is applied twice: first to assess whether or not the defendant did breach his or her duty of care, and, second, to delimit whether or not the defendant’s behavior was a proximate cause of the harm suffered by the victim. However, under a strict liability rule, the Hand formula is applied only once when the proximate causation question is raised. Traditional law and economics analysis has almost always taken the normative question raised by the causation requirement as given, which is a potential major problem due to the importance of scope of liability or proximate causation in legal practice. Defining the scope of liability, that is to say, the boundaries of the pool of potential defendants, is the basic legal policy decision for each and every liability rule. In the normative model presented in this paper, the government first chooses efficient scope of liability, and given the scope of liability, the government then decides the liability rule and damages that guarantee efficient precaution. In the article, most known scope of liability rationales developed by both common law and civil law systems are discussed in order to show the substantial common ground between negligence and strict liability.