The US Supreme Court has significantly weakened the nation’s Environmental Protection Agency (EPA). 

Chief Justice John Roberts and his five conservative colleagues have come together on a 6-3 ruling, finding that the EPA does not have the authority to force electric utilities to close down coal-fired power plants and shift to renewable generation. 

They argued that the US Congress has not given the agency the authority to issue such sweeping carbon regulations, claiming the main federal air pollution law, the Clean Air Act, did not have that intention when it was written over 50 years ago. 

“There is little reason to think Congress assigned such decisions to the Agency,” Roberts wrote. 

“A decision of such magnitude and consequence rests with Congress itself.”

But the court’s three other judges have written dissenting opinions, contending that the Clean Air Act does indeed give the EPA the power to combat climate change.

Dissenting Justice Elena Kagan said a portion of the law allowing the EPA to regulate pollutants “may reasonably be anticipated to endanger public health or welfare… carbon dioxide and other greenhouse gases fit that description”. 

One strange aspect of the decision is that such a carbon rule had not actually been put forth by the administration of US President Joe Biden. 

Instead of waiting for regulators to act or for the Biden administration to bring its own proposal, the court got on the front foot and took up the West Virginia v. EPA case. 

This allowed the Supreme Court to strike down the never-executed centrepiece of the Obama administration’s climate policy: the Clean Power Plan. 

The decision means the EPA has been seriously diminished in its ability to directly regulate carbon dioxide from the smokestacks of power plants.

However, reports say EPA officials are already looking at other potential tools for cutting pollution from power plants.