As I posted earlier, in Murray, et al v. EPA , plaintiff Murray Energy Corporation seeks to enjoin EPA's Clean Power Plan rule even before it has been issued as a Final Rule.  The Clean Power Plan proposes to regulate the carbon emissions of existing power plants under the Clean Air Act. 

Last week, the states of New York, State of Connecticut, State of Delaware, State of Maine, State of New Mexico, State of Oregon, State of Rhode Island, State of Vermont, State of Washington, Commonwealth of Massachusetts, District of Columbia filed notice of their intention to participate as amicus curiae 

In June, Alabama, Kentucky, Oklahoma, South Carolina, West Virginia, Alaska, Nebraska, Ohio and Wyoming also filed an amicus brief in this case.

Assuming that the northeastern states support the Clean Power Plan, it sets up a sort of "Blue v. Grey over Green" battle, with the western states thrown in as well.   

There was also an interesting decision in the D.C. Circuit last week, lifting a stay on the EPA's Cross-Border Pollution Rule.  But, additional issues remain to be resolved in the DC Circuit case, so there will likely be more action on this critical rule.