Since the early days of the Obama administration, conservative politicians have railed against the President's "war on coal." As evidence of this supposed siege, they point to a series of rules issued by the Environmental Protection Agency that require the nation's power plants to cut their emissions of several types of air pollution. It's true that, because coal produces far more pollution than any other major energy source, the EPA's rules are expected to further reduce the fuel's already shrinking share of the electricity market, in favor of cleaner options like natural gas, wind and solar power. Even so, the rules are hardly the "unprecedented regulatory assault" that opponents make them out to be. Instead, they are merely the latest chapter in a longstanding quest for redemption, a multi-decade struggle to overcome a tragic flaw in our nation's most important environmental law.In 1970, a nearly unanimous Congress passed the Clean Air Act, which had the remarkably ambitious aim of eliminating all air pollution that posed a threat to public health or welfare. But there was a problem: for some of the most common pollutants, Congress empowered the EPA to set emission limits only for newly constructed industrial facilities-most notably, power plants. Existing facilities, by contrast, would be largely exempt from direct federal regulation-a regulatory practice known as "grandfathering." What lawmakers didn't anticipate was that imposing costly requirements on new plants while giving existing ones a pass would simply encourage those old plants to stay in business much longer than originally planned. For almost half a century now, the core problems of U.S. environmental policy have flowed inexorably from the smokestacks of these coal-fired clunkers, which continue to pollute at far higher rates than their younger peers.In Struggling for Air, Richard L. Revesz and Jack Lienke chronicle the political compromises that gave rise to grandfathering, its deadly consequences, and the repeated attempts-by Presidential administrations of both parties-to make things right.