Advocates and critics of regulation make familiar but competing claims. Either regulations hamper economic growth, or their inadequacies contribute to economic failures. Either regulations stifle innovation, or they are needed to keep us safe. Of course, all of these claims could be at least partly true, at least with respect to specific types of regulation or different types of public problems. But so far, authoritative answers have remained far too elusive. Calls for looking back to determine regulation’s positive and negative effects have grown over the last several years. One salient concern centers on the problem of keeping bad regulations on the books. Another focuses on the cumulative burdens created when new rules are piled on top...