The Supreme Court’s order is not a ruling, but it does signal that the CPP could be successfully challenged in the courts, which have not had a chance to evaluate it yet. The move is also surprising as the Supreme Court has some fairly strict rules for granting stays. In fact, it’s believed that this is the first time the Supreme Court has stayed a regulation. The Supreme Court only issues stays when there is a reasonable probability that four justices will agree to review the case and a fair prospect that five justices could vote to overturn a lower court ruling, according to the Wall Street Journal.

After an earlier request for a stay of the CPP was rejected in a lower court, a group of 27 states, state agencies, Murray Energy and the National Mining Association, along with other associations, petitioned the Supreme Court to stay the implementation on the grounds of governmental overreach. The coalition was led by Patrick Morrisey, the Republican attorney general from West Virginia. “We are thrilled that the Supreme Court realized the rule’s immediate impact and froze its implementation, protecting workers and saving countless dollars as our fight against its legality continues,” Morrisey said. When the lower court rejected the stay, the coalition was worried that the EPA, which uses an overloaded court system to its advantage, would evade the checks and balances from the judicial branch over the executive branch until after the damage had been done, much as it did with the Utility MACT Rule.

As many as 30 lawsuits have been filed against the EPA, challenging the CPP and raising issues under the Clean Air Act — an area that has not really been explored by the courts. The states challenging the rule say the stay was needed or they would need to enact laws, revise regulations and devote vast sums of money to comply with the CPP. Similarly, power generators said that, without a stay, coal-fired power power plants would be forced to close until the issue was resolved.

“The EPA lacks the authority to force such radical change,” Morissey said. “Congress soundly rejected this proposal once, and we urge the EPA to withdraw the rule now as implementation would devastate countless jobs, increase utility costs and jeopardize the nation’s energy grid.”

The immediate impact of the stay is unclear. States have been encouraged to ignore the September compliance deadline and they will likely do that now if they so choose. Assuming the EPA does not withdraw it, the rule will likely be heard by the Supreme Court during the 2016-2017 term after the appeals process. The CPP requires all final plans to be submitted no later than 2018. Should the rule survive the courts’ scrutiny, the next president will face the decision of repealing the regulation.