The US Court of Appeals for the District of Columbia Circuit on Tuesday struck down the Affordable Clean Energy (ACE) rule, ending the Trump administration’s efforts to relax rules regarding the emission of greenhouse gases from power plants.

The Environmental Protection Agency (EPA) under former president Donald Trump had promulgated the ACE rule in an attempt to repeal and replace the Obama-era Clean Power Plan that was designed to reduce carbon dioxide emissions for combating climate change. The plan has been on hold as it has been held up in court since 2016. The ACE rule would have given the states the authority to set their own air quality standards and establish regulations for individual power plants within them.

A broad coalition of environmental groups, states, cities and power companies filed suit to block the ACE rule after it was finalized in 2019. In defending the repeal of the Clean Power Plan and the enactment of the ACE rule, the EPA argued that the express language of section 7411 of the Clean Air Act mandates that the EPA can only regulate greenhouse gas emissions at a stationary source, namely the power plants themselves. However, the court found that the EPA’s reading of the Act “is simply not supported by the text, let alone plainly and unambiguously required by it.” The court said that the EPA has “ample discretion” in how it carries out its duties, but “it may not shirk its responsibility by imagining new limitations that the plain language of the statute does not clearly require.” The court vacated the rule and remanded it to the EPA “to consider the question afresh.”

The incoming Biden administration is unlikely to appeal the ruling.