Over the past number of years there has been considerable work in law and economics on optimal law enforcement. Overall this research has emphasized theoretical modelling focusing on the effects of penalties on criminal behavior, the effects of plea bargaining on convictions, and the effects of expenditures by defendants to avoid prosecution and conviction. While the models that have developed have made important contributions, they all have emphasized that, at least over some range of crimes, uniformly maximal penalties are most efficient. Dr. Andreoni questions this assumption and takes the view that much more can be learned about penalties if more explicit account were taken of the process by which society determines that an accused person deserves to be punished. He focuses explicitly on the role of reasonable doubt since this standard (i.e., whether evidence is convincing "beyond a reasonable doubt") influences judges, juries, and prosecutors engaged in plea bargaining. The work is especially noteworthy in combining theoretical modelling, field study, and experimental research. His empirical efforts will range from a reanalysis of the Ehrlich data on the deterrent effects of punishment taking into consideration reasonable doubt to role playing studies of criminal behavior and experimental jury simulations under varying penalty conditions. The potenial yield from this research is considerable. Since standard models of optimal penalty do not take reasonable doubt into account, by taking this step (under the straightforward model of reasonable doubt and under a model that also considers institutional features of the legal system), this work offers a welcome new approach to modelling crime and punishment. Such work is of pathbreaking importance because it promises to bring theory and reality much closer together.
