Modeling Legal Rules

Abstract

Common law rules admit of exceptions. When a court, especially a higher court, finds that the routine application of a rule would result in an injustice, it is likely to distinguish. It will concede that yes, the case does appear to fall under the rule as it is currently understood; but will insist that there are further factors, not mentioned in the rule (though perhaps acknowledged in other rules in other parts of the law) that distinguish this case from the cases that the existing rule was meant to cover. The court will conclude that in this case the verdict that the existing rule suggests would be wrong. Nevertheless, the old rule does not die. When the writers of case books come to accommodate the new ruling it will come in as an amendment: the old rule was correct except under these new circumstances.