On February 9, 2016, the Supreme Court stayed implementation of the Carbon Pollution Emission Guidelines for Existing Electric Generating Units (the Guidelines) pending judicial review. The Guidelines are one component of President Obama’s Clean Power Plan, which is intended to reduce carbon dioxide (CO2) emissions by forcing a shift away from certain fuels, particularly coal, toward renewable energy sources, such as solar and wind, coupled with increased efficiency and demand side management. Under the Guidelines, power plants would be required to reduce carbon emissions to EPA-established levels beginning in 2022. Under Clean Air Act Section 111(d), the states would have to develop plans detailing measures to achieve EPA’s state-specific emission levels and submit the plans for EPA approval in 2018.

The CPP’s supporters claim the regulations are necessary to prevent and mitigate the harms climate change could pose to human health and the environment. CPP opponents claim it is unnecessary because the electricity market, without governmental coercion, was already drastically reducing carbon emissions from coal-fired power plants; now at a 27-year low. Opponents also claim the rules will cause unnecessary lost revenue, layoffs, and higher prices for energy consumers. Areas where coal is both mined and used to produce electricity are expected to feel the strongest negative effects.

Although implementation of the existing source Guidelines has been judicially halted, EPA and many environmental activist groups are publically urging states to ignore the stay and “aggressively” move forward with plans to reduce greenhouse gas emissions. Administrator Gina McCarty claims “the train has left the station” and “renewables are the energy source of the future.” So far, 20 states, including Arkansas, Illinois, Maryland, Pennsylvania and Virginia have indicated they are moving forward with compliance planning.

More importantly for purposes of this article, the recent death of Supreme Court Justice Antonin Scalia (who passed away just four days after the Supreme Court issued the stay) could have an enormous effect on the fate of the rule. Justice Scalia was one of the five justices to vote in favor of the stay; the other four justices voted against the stay.

Before Justice Scalia’s death, the odds seemed to be against EPA because the stay signaled skepticism among at least five justices that the Guidelines were valid. Many believe that Justice Scalia’s “intellectual fingerprints” were apparent in the stay. Even with the common caveat that “predicting Supreme Court outcomes is a bit like reading tea leaves,” everyone agrees that the likelihood of the Guidelines being upheld improved with Justice Scalia’s death.

Likewise, many believe that if President Obama’s nominated justice is confirmed, the newly reconstituted court will likely affirm when the case is ultimately heard. If, however, the Senate decides not to confirm a new justice until one is nominated by the new president in 2017, a different result may come from the new court. If only eight justices hear the case, a 4-4 tie effectively affirms the lower court decision.

So what will happen going forward? First, litigation will proceed in the D.C. Circuit where the odds are the court will uphold EPA’s action; not only because those particular judges are viewed as more liberal but also because lower courts reviewing agency action often defer to the agency.

Regardless of the D.C. Circuit’s decision, the loser will petition the Supreme Court for review. It takes four justices to grant a petition for writ of certiorari. Four justices voted against the stay, so there are likely to be four votes to grant the petition no matter who wins in the D.C. Circuit. Assuming that the Court will grant certiorari to hear the case, that’s when things will get really interesting.