The Supreme Court agreed Friday to hear a set of cases challenging the Environmental Protection Agencys authority to regulate greenhouse gases, potentially limiting the Biden administrations options to curb planet-heating pollution.

The lawsuits, filed by Republican-controlled states and a West Virginia oil company, aim to curb the federal governments power to mandate a transition away from fossil-fueled power plants.

If the high courts 6-3 conservative majority finds in favor of the plaintiffs, the ruling wouldnt eliminate the federal governments ability to regulate carbon dioxide emissions under the Clean Air Act, a legal determination known as the endangerment finding. It would, however, restrict the legal routes through the Clean Air Act for enacting such rules. That could make it harder for the United States to hit its goal to cut emissions in half by the end of this decade.

In an updated grant of certiorari, the Supreme Court said it plans to ask questions about a legal issue known as non-delegation doctrine, which Cornell Law School describes as the principle in administrative law that Congress cannot delegate its legislative powers to other entities.

A ruling that explicitly requires Congress to pass new laws allowing EPA to regulate carbon emissions could prove an even bigger setback.

The White House abandoned its main legislative proposal to pay utilities to produce more zero-carbon electricity, and fine those that fail to increase their clean output each year, after Sen. Joe Manchin (D-W.Va.) said hed torpedo the administrations agenda if Democrats included the measure in a sweeping spending bill currently under consideration. Democrats are also expected to lose control of Congress in next years election.

At issue is a legal snafu from 1990, when then-President George H.W. Bush mistakenly signed two slightly differing versions of the Clean Air Act into law, creating legal confusion over the line between federal and state power when it came to regulating greenhouse gases.