In the essay that follows, Professor Lempert pursues the lay versus professional issue, once again in the jury context. He begins by setting forth a general theory of the likely contribution of each. He then applies his posited theory to two issues of current interest to the bar: jury size and the peremptory challenge. The essay originated as testimony (prepared jointly with Dr. Jay Schulman) before a Senate subcommittee considering a bill (S. 2074, 95th Congress, 1st Session) to reduce the number of peremptory challenges in civil cases from three to two and also to require all federal district courts to switch from twelve-member to six-member juries. (Now most district courts use six-member juries under local rule with the blessing of th...