When the quality of a good is at the discretion of the seller, how can buyers assure that the seller provides the mutually efficient level of quality? Contracts that provide a bonus to the seller if the quality is acceptable or impose a penalty on the seller if quality is unacceptable can, in theory, provide efficient incentives. But how are such contracts enforced? While the courts can be used, doing so involves high real costs. Informal enforcement, involving a loss of reputation and future access to the market for any party that defaults on a contract, may often be a better alternative. This paper explores the use of both formal and informal enforcement mechanisms, provides a rationale for a variety of observed market mechanisms, and then generates a number of testable hypotheses.

This paper discusses the nature, and magnitude, of externalities associated with automobile use, including local and global pollution, oil dependence, traffic congestion and traffic accidents. It then discusses current federal policies affecting these externalities, including fuel taxes, fuel economy and emissions standards, and alternative fuel policies, summarizing, insofar as possible, the welfare effects of those policies. Finally, we discuss emerging pricing policies, including congestion tolls, and insurance reform, and summarize the appropriate combination of policies to address automobile externalities.