Today the Supreme Court will hear polluter arguments against the Environmental Protection Agency's (EPA) vital Mercury and Air Toxics Standards (MATS), a long-overdue protection finalized in 2012 that will help guard our families, air, water, and wildlife from dangerous toxic pollution that comes from coal plants. These vital protections are critically important to public health…As the nation's largest source of mercury emissions, coal plants are responsible for 48 tons of this toxin being released every year. It falls from the smokestacks into our rivers, lakes, and oceans, making its way into the aquatic food chain, and perhaps to the seafood counter at your local grocery store…[T]he vast majority of coal plants across the country have already installed or are planning to install the needed equipment to comply with the mercury protections. These plants that have already cleaned up have shown that protecting our communities from this pollution isn't just possible but is already happening and is the right thing to do. The most stubborn polluters, however, are still challenging the EPA on whether the agency adequately considered their costs before finalizing the mercury protections…The Supreme Court must stand up for public health…