Economist Terry L. Anderson has been lecturing on “Environmental Markets” these last two days at the Law & Economics Institute sponsored by George Mason University. His argument is simple: instead of treating the environment as an open-access commons, we are better off by assigning property rights to natural resources and letting people trade these rights. In essence, he extends the domain of the Coase theorem to environmental resources. In brief, the Coase theorem is the idea in economics that people will negotiate and enjoy gains from trade when there are no legal or economic impediments to trade. Is this wishful thinking or a tautology?