On February 9, 2016, the U.S. Supreme Court issued a 5-4 decision staying implementation of the Clean Power Plan until the D.C. Circuit rules on challenges to the Plan. The Court left open the possibility that it would review the D.C. Circuit’s ultimate decision.

The decision delays President Obama’s Climate Action Plan. The Clean Power Plan is its key climate change rule. It requires states and utilities to reduce carbon dioxide (CO₂) emissions by generating less electricity from coal, and more from lower carbon-emitting sources like natural gas, or zero-carbon sources like solar and wind. The Plan has an ambitious goal: to reduce CO₂ emissions 32% below 2005 levels by 2030.

Some relevant background: On January 21, 2016, the D.C. Circuit refused to stay the Clean Power Plan while litigation is pending before it. Opponents of the rule, including 29 states and state agencies and several industry and trade groups, appealed that decision to the Supreme Court.

The stay will be in place at least until the D.C. Circuit rules on the pending challenges, likely late this year. Briefing deadlines are in April, and oral argument is scheduled in early June. The Supreme Court’s stay order will also remain in effect if the Court decides to review the D.C. Circuit’s decision, which it is expected to do, regardless of the outcome.

What are the implications of the stay? In the short term, the September 6, 2016 deadline for states to either submit their state plans or request a two-year extension will be postponed.

The Supreme Court’s action was unusual. The 5-4 vote suggests that the Court was persuaded that the significant challenges to the rule and the economic consequences of implementing it outweighed EPA’s interests in addressing climate change this year.