Two of President Barack Obama ’s top pollution-control measures face courtroom tests tomorrow as coal-dependent utilities, miners and some states challenge what they call overreach by the Environmental Protection Agency. Efforts to regulate pollutants that cause smog and soot, as well as mercury from coal plants, have moved in fits and starts for more than a decade. If both rules go forward it would cause power producers such as American Electric Power Co. (AEP) and Southern Co. (SO) to shutter old plants or invest billions of dollars in pollution-control technology. Health and environmental groups say the rules clean the air and reduce heart attacks, asthma and related illnesses. The decisions in these cases — one being argued before the Supreme Court and the other in federal appeals court — could have a longstanding impact on how the Clean Air Act is implemented. “This is the biggest day for clean […]