Law & Economics Working Papers
If a plaintiff brings two claims, each with a 0.4 probability of being valid, the plaintiff will usually lose, even if the claims are based on independent events, and thus the probability of at least one of the claims being valid is 0.64. If a plaintiff brings two independent claims, and each of them is too weak to justify a remedy, the plaintiff will usually lose, even if the claims are jointly powerful enough to justify a remedy. Thus, as a general rule courts refuse to engage in what we call factual aggregation (the first case) and normative aggregation (the second case). (We also identify other forms of aggregation.) Yet we show numerous exceptions to this rule in private and public law. Notably, in public law the hybrid rights doctrine permits courts to aggregate two weak constitutional claims as long as one involves free exercise of religion. In private law, certain tort and contract doctrines also permit aggregation. We criticize the courts' inconsistent approaches to aggregation, and propose conditions under which courts should (and should not) aggregate.
Eric Posner & Ariel Porat, "Aggregation and Law" (John M. Olin Program in Law and Economics Working Paper No. 587, 2012).