A federal appeals court on Friday will hear oral arguments on the Environmental Protection Agency's expensive mercury and air pollutant rules for power plants, which could lead to the end of the regulations.
The Supreme Court in June sent the regulations back to the D.C. Circuit Court of Appeals, ruling that the EPA had to assess the cost of the rules because the agency did not have the discretion to disregard the cost of complying with the regulations.
The decision means there is legal precedent directing how EPA assesses other utility regulations deemed costly, which gives states ammunition in opposing the agency's landmark climate change rules for power plants, notably the Clean Power Plan. The plan is the centerpiece of President Obama's climate change agenda and his hope of securing a global deal to lower emissions in Paris this month.