There has been an important court ruling on the greenhouse gas issue. Today - the Supreme Court in a divided decision ruled that the EPA had exceeded its authority by changing emissions thresholds for greenhouse gases to regulate more stationary sources. The ruling partially reverses the 2012 Appeals Court decision.
The Supreme Court did say that EPA can regulate greenhouse gas emissions from industries already required to get air permits for other pollutants.
According to the report in USA Today - EPA is getting almost everything it wants, but does for EPA to go further, it would be contracting the Congress. The ruling is seen by Scalia as a step in reasserting the separation of powers between Congress and the Administrative branches of government.
Today's ruling may not significantly impact greenhouse gas regulations for power plants, and petroleum refineries.