Our legal system is committed to the idea that private markets and the law of contracts that supports them are the primary institutions for allocating goods and services in a modern economy. Yet the market paradigm, this book argues, leaves substantial room for challenge. For example, should people be permitted to buy and sell blood, bodily organs, surrogate babies, or sexual favors? Is it fair to allow people with limited knowledge about a transaction and its consequences to enter into it without guidance from experts?