Information, Litigation, and Common Law Evolution

It is common in the legal academy to describe judicial decision trends leading to new common law rules as resulting from conscious judicial effort. Evolutionary models of litigation, in contrast, treat common law as resulting from pressure applied by litigants. One apparent difficulty in the theory of litigation is explaining how trends in judicial decisions favoring one litigant, and biasing the legal standard, could occur. This article presents a model in which an apparent bias in the legal standard can occur in the absence of any effort toward this end on the part of judges. Trends can develop favoring the better-informed litigant whose case is also meritorious. Although the model does not suggest an unambiguous trend toward efficient legal rules, it does show how private information from litigants becomes embodied in common law, an important part of the theory of efficient legal rules.