Retrospective, or ex post, analysis of U.S. federal regulation aims to rigorously document regulatory outcomes using cost, benefit, and distributional metrics. This paper presents nine new case studies involving a total of 34 comparisons of ex ante and ex post estimates from a diverse group of environmentally oriented rules. Despite the potential for selection bias and other limitations of the case study approach, the results suggest a slight tendency to overestimate both costs and benefits (or effectiveness) of regulation. This paper considers various analytic issues relevant to developing credible baselines for comparison, and offers policy lessons regarding the design of emissions trading programs along with approaches for incorporating uncertainty into both preregulatory studies and policy designs. Recommendations to facilitate and support future retrospective analyses are also presented.
Retrospective Analysis of U.S. Federal Environmental Regulation