Regulation generates both legal and illegal responses. Standard economic analysis emphasizes the impact of regulation on a small number of variables, typically price and quantity. However, the regulatory process plays out with many actors responding along many margins. The responses to a regulation—and the interest groups involved—are affected by what is being measured, which metrics are used, the transparency of the regulatory process and the regulation’s consequences, how technology evolves, and which mechanisms are used for enforcement. Several examples illustrate the diverse ways in which regulatory processes have played out historically.