New York Times: n 1990, by an overwhelming majority, Congress amended the Clean Air Act to establish a market for electric utilities to trade the right to emit sulfur dioxide, one of the main contributors to acid rain. The law was based on a simple economic insight. If utilities facing high costs to cut emissions could, instead, buy allowances to pollute from those who could cut emissions for less, reducing overall pollution would be much cheaper. The idea had been successfully used before, during the Reagan administration,...