The coal and power industries argued that controlling mercury emissions costs too much. Obama took a stand. In his 2012 State of the Union address, Obama backed the mercury ruling.
All this political maneuvering gave the EPA's regulation requiring coal plants to clean up their act a high profile. Now it is back in the news, as the Supreme Court has ruled against the Agency on the question of whether it is "appropriate and necessary" to restrict emissions of mercury from power plants. "Appropriate and necessary" are the key words in the Clean Air Act that give EPA authority to act - in fact require EPA to regulate.
At its root, the Supreme Court has ruled that EPA did not adequately consider the costs of the mercury regulation. But that ruling relates only to the first step in the overall process. EPA did not believe cost needed to play a role in the initial decision that it was "appropriate and necessary", so they put the work of regulating on the agenda without further ado.
The dissent by Justice Elena Kagan, (representing co-dissenters Ruth Bader Ginsburg, Stephen Breyer and Sonia Sotomayor), points out the inanity of knocking EPA on this point:
"Over more than a decade, EPA took costs into account at multiple stages and through multiple means as it set emissions limits for power plants. And when making its initial 'appropriate and necessary' finding, EPA knew it would do exactly that -- knew it would thoroughly consider the cost-effectiveness of emissions standards later on."
Initial reactions suggest the decision will have little real implication. The ruling does not overturn the regulation but sends the matter back to a lower court. Most power companies have shuttered facilities not able to be upgraded and applied the required "best available" controls on power plants still in operation to meet the April 2015 deadline set by the regulation.
Many believe that this ruling will not affect EPA's actions on the climate changing gas carbon dioxide either, because EPA took costs into account throughout the process in that case. However, others opine that the fact that the mercury costs were already expended before today's ruling may make the court more amenable to block future regulations from taking effect until the legal challenges have been clarified.