Professor Klein has published research on policy issues including toll roads, urban transit, auto emission, credit reporting, and the Food and Drug Administration. He has also written on spontaneous order, the discovery of opportunity, the demand and supply of assurance, why government officials believe in the goodness of bad policy, and the relationship between liberty, dignity, and responsibility.
Klein is the coauthor of Curb Rights: A Foundation for Free Enterprise in Urban Transit, editor of Reputation: Studies in the Voluntary Elicitation of Good Conduct, and editor of What Do Economists Contribute?
Recently, Klein has coauthored with Alex Tabarrok a comprehensive Web site on the Food and Drug Administration (FDAReview.org), and co-edited with Fred Foldvary a book The Half-Life of Policy Rationales: How New Technology Affects Old Policy Issues (New York University Press, 2003).