New attempts to moderate energy-price movement with controls on commodity trading might, like much regulation of markets, yield unsavory surprises. The US Commodity Futures Trading Commission is considering new controls on off-exchange trading of energy derivatives. And the Department of the Treasury has sent Congress a plan for trading reform. Propelling this regulatory push is the belief that excessive speculation aggravates swings in energy prices and makes markets susceptible to manipulation. Little about the effort—other than the proposed extension to energy of regulation now focused on agricultural commodities—is new, points out Michael Lewis of Deutsche B...