Abstract: Mass exposure accidents, such as those involving DES and asbestos, pose unique problems under the traditional rules and methods of "private law" litigation. Two problems stand out: first, the preponderance-of-the-evidence rule often makes it impossible for plaintiffs to prove causation; second, the substantial costs of litigating mass exposure claims on a case-by-case basis make such claims unattractive to plaintiff attorneys. Professor Rosenberg argues that the resulting preclusion of mass exposure claims frustrates the basic deterrence and compensation objectives of the tort system. He proposes that courts determine causation under a proportionality rule, which would hold manufacturers of toxic agents liable for the proportion of total injuries attributable to their products. In addition, he argues that courts should allow mass exposure cases to proceed as class actions and should employ such innovative remedial techniques as damage scheduling and insurance fund judgments. These "public law" measures, according to Professor Rosenberg, would improve the tort system's ability to fulfill the goals of maximizing social welfare and protecting individual entitlements.