Tractebel Energy Marketing, a power plant designer and builder, wanted to build a power plant. Environmental Protection Agency regulations required new power plants to offset the anticipated increase in overall emissions by purchasing emission reduction credits. Companies acquired these credits by installing better technology in existing plants or shutting down existing operations. Through a broker, DuPont entered into a contract to sell 1,000 tons of nitrogen oxides emission credits to Tractebel. Shortly thereafter, however, the New Jersey Department of Environmental Protection revoked DuPont’s credits, citing new regulations. When DuPont refused to perform the contract, Tractebel sued for breach. What arguments will DuPont claim in its defense? Who will prevail in this action? [Tractebel Energy Marketing, Inc. v. E.I. DuPont DeNemours & Co., 118 S.W.3d 60 (Tex. App.–Houston 2003).]