Complex Evidence in Litigation

Expertise

The typical jury is obviously far less expert than the judge in one key respect—expertise on the law as it pertains to the case. But because juries do not provide a rationale for their verdict, we only rarely know that a jury has made a “mistake” on the law, and juries may not feel particularly hindered by their lack of legal expertise. What may matter far more is expertise with respect to the technical issues that may arise at the trial, involving the economic analysis of market power, the engineering of heavy machinery, the etiology of a disease, or the epidemiology of toxic exposure. Here, judges may outperform the average juror; judges are above average in education and intelligence, and they may have relevant experience from past trials. But we shouldn't overestimate either intelligence or experience. Studies of expertise show that it can take a decade or more of concerted effort to [Page 128]develop true mastery of a technical skill. Graduate students are highly intelligent and still struggle for months to successfully complete their more technical graduate courses. And today's judges are likely to have far less actual trial experience than their predecessors of earlier generations. As a sample of the community, the jury may collectively have more relevant expertise in nonlegal issues than the relevant judge.

Groups as Information Processors

In the 1950s, Irving Lorge and Herbert Solomon deduced that, ceteris paribus, groups are better situated than their individual members to find correct answers. If p is the probability that any given individual will find the “correct” answer, then the predicted probability P that a collectivity of size r will find the answer is P = 1 − (1 − p)r. More recently, Lu Hong and Scott Page have derived theorems proving that cognitively diverse groups—defined with respect to the perspectives and schemas they use to tackle a problem—can outperform even their best members. But this model, like that of Lorge and Solomon, proves group competence, not group performance. Empirically, we know that performance often falls short of competence.

...