Berkeley Program in Law and Economics

Reforms to the Joint and Several Liability rule (JSL) are one of the most common tort reforms and have been implemented by most US states. JSL allows plaintiffs to claim full recovery from one of the defendants, even if that defendant is only partially responsible for the tort. We develop a theoretical model that shows that the efficiency of the JSL rule depends critically on both whether the care taken by potential tortfeasors is observed, and on how the actions of the potential tortfeasors interact to cause the harm. We then provide evidence that reforms of the JSL rule have been accompanied by reductions in the accidental death rate in the U. S. This result is consistent with the hypothesis that the reform of JSL causes potential tortfeasors to take more care.