Greenwire: Former Supreme Court Justice John Paul Stevens, the author of a seminal decision on when courts must defer to agencies, said the high court's decision this year to invalidate U.S. EPA's air standards for mercury and other toxics was "truly mind-boggling."
In June, the court ruled that EPA should have considered costs in determining whether it was "appropriate and necessary" to promulgate its mercury and air toxics standards, or MATS.
More than 20 Republican-led states and various industry groups...