In this paper we discuss a new tort liability rule, which we call super-symmetric comparative negligence and vigilance. When both injurer and victim in an accident are negligent, it provides for liability shares that depend on the degrees of negligence of the two parties, similar to the standard comparative negligence rule. Unlike standard liability rules, however, when both parties are vigilant (i.e., taking more care than is efficient), the rule provides for liability shares that depend on the parties’ degrees of vigilance. Moreover, when one party is negligent and the other is non-negligent, our rule provides for variable liability shares, that respond to both carefulness and carelessness of the parties. Our liability rule is equitable; it has no discontinuity at the efficient point where both parties are just meeting their standards of care; and it provides incentives that guarantee the injurer and victim will choose the efficient care levels. This paper does not include theorems and proofs; rather it explains the results with the aid of a simple example, laid out in an easy 3 x 3 table.
