The Supreme Court is hearing a case its conservative majority could use to hobble Biden administration efforts to combat climate change.

       The administration already is dealing with congressional refusal to enact the climate change proposals in President Joe Biden's Build Better Back plan.

       Now the justices, in arguments Monday, are taking up an appeal from 19 mostly Republican-led states and coal companies over the Environmental Protection Agency's authority to limit carbon dioxide emissions from power plants.

       The court took on the case even though there is no current EPA plan in place to deal with carbon output from power plants, a development that has alarmed environmental groups. They worry that the court could preemptively undermine whatever plan Biden's team develops to address power plant emissions. Biden has pledged to cut greenhouse gas emissions in half by the end of the decade.

       A broad ruling by the court also could weaken regulatory efforts that extend well beyond the environment, including consumer protections, workplace safety and public health. Several conservative justices have criticized what they see as the unchecked power of federal agencies.

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       Those concerns were evident in the court's orders throwing out two Biden administration policies aimed at reducing the spread of COVID-19. Last summer, the court's 6-3 conservative majority ended a pause on evictions over unpaid rent. In January, the same six justices blocked a requirement that workers at large employers be vaccinated or test regularly and wear a mask on the job.

       West Virginia Attorney General Patrick Morrissey, speaking at a recent event in Washington, cast the power plant case as about who should make the rules. “Should it be unelected bureaucrats, or should it be the people’s representatives in Congress?" Morrisey said. West Virginia is leading the states opposed to broad EPA authority.

       But David Doniger, a climate change expert with the Natural Resources Defense Council, said the Supreme Court's consideration of the issue is premature, a view shared by the administration.

       He said the administration's opponents are advancing “horror stories about extreme regulations the EPA may issue in the future. The EPA is writing a new rule on a clean slate.”

       The power plant case has a long and complicated history that begins with the Obama administration's Clean Power Plan. That plan would have required states to reduce emissions from the generation of electricity, mainly by shifting away from coal-fired plants.

       But that plan never took effect. Acting in a lawsuit filed by West Virginia and others, the Supreme Court blocked it in 2016 by a 5-4 vote, with conservatives in the majority.

       With the plan on hold, the legal fight over it continued. But after President Donald Trump took office, the EPA repealed the Obama-era plan. The agency argued that its authority to reduce carbon emissions was limited and it devised a new plan that sharply reduced the federal government's role in the issue.

       New York, 21 other mainly Democratic states, the District of Columbia and some of the nation's largest cities sued over the Trump plan. The federal appeals court in Washington ruled against both the repeal and the new plan, and its decision left nothing in effect while the new administration drafted a new policy.

       Adding to the unusual nature of the high court's involvement, the reductions sought in the Obama plan by 2030 already have been achieved through the market-driven closure of hundreds of coal plants.

       The Biden administration has no intention of reviving the Clean Power Plan, one reason Solicitor General Elizabeth Prelogar, the administration's top Supreme Court lawyer, argues the court should dismiss the case.

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       Some of the nation's largest electric utilities, serving 40 million people, are supporting the Biden administration along with prominent businesses that include Apple, Amazon, Google, Microsoft and Tesla.

       A decision is expected by late June.