In the casual political rhetoric about environmental regulation, it is often claimed that the U.S. government regulates on the basis of risk while the European Union (or EU member states) regulates on the basis of hazard. The implication is that the U.S. government relies on a more rigorous, scientific process of assessment than does the EU, which allegedly helps explain why the EU is more pro-regulation than is the United States.An alternative view, advanced originally by the late Professor Aaron Wildavsky of the University of California-Berkeley and amplified in a recent book by Professor Jonathan Wiener of Duke University, and colleagues, is that societies engage in a process of “risk selection.” What worries some societies does not worry others.