In a 6-3 decision that will seriously hinder America’s ability to stave off disastrous global heating, the Supreme Court, which became dominated by rightwing justices under the Trump administration, has opted to support a case brought by West Virginia that demands the US Environmental Protection Agency (EPA) be limited in how it regulates planet-heating gases from the energy sector.

The case, which was backed by a host of other Republican-led states including Texas and Kentucky, was highly unusual in that it was based upon the Clean Power Plan, an Obama-era strategy to cut emissions from coal-fired power plants that never came into effect. The Biden administration sought to have the case dismissed as baseless given the plan was dropped and has not been resurrected.

Not only was this case about a regulation that does not exist, that never took effect, and which would have imposed obligations on the energy sector that it would have met regardless. It also involves two legal doctrines that are not mentioned in the constitution, and that most scholars agree have no basis in any federal statute.

However, the Supreme Court has sided with West Virginia, a major coal mining state, which argued that “unelected bureaucrats” at the EPA should not be allowed to reshape its economy by limiting pollution — even though emissions from coal are helping cause worsening flooding, heatwaves, and droughts around the world, as well as killing millions of people through toxic air.

“Capping carbon dioxide emissions at a level that will force a nationwide transition away from the use of coal to generate electricity may be a sensible ‘solution to the crisis of the day’,” wrote Chief Justice John Roberts in the opinion. “But it is not plausible that Congress gave EPA the authority to adopt on its own such a regulatory scheme in Section 111(d). A decision of such magnitude and consequence rests with Congress itself, or an agency acting pursuant to a clear delegation from that representative body.”

Roberts was joined by the conservative justices Samuel Alito, Neil Gorsuch, Brett Kavanaugh, and Amy Coney Barrett. The three liberal justices, Sonia Sotomayor, Elena Kagan, and Stephen Breyer dissented. It is the most important climate change case to come before the Supreme Court in more than a decade.

But the ruling could also have sweeping consequences for the federal government’s ability to set standards and regulate in other areas, such as clean air and water, consumer protections, banking, workplace safety, and public health. It may prove a landmark moment in conservative ambitions to dismantle the “regulatory state,” stripping away protections from Americans across a wide range of areas.

It could fundamentally change what the federal government is and what it does. And, as justice Elena Kagan pointed out in her dissent, it could leave technical decisions to a political body that may not understand them.

“First, members of Congress often don’t know enough — and know they don’t know enough — to regulate sensibly on an issue. Of course, members can and do provide overall direction. But then they rely, as all of us rely in our daily lives, on people with greater expertise and experience. Those people are found in agencies,” she wrote.

Several conservatives on the court have criticized what they see as the unchecked power of federal agencies, concerns evident in orders throwing out two Biden policies aimed at reducing the spread of Covid-19.

Last summer, the six-to-three conservative majority ended a pandemic-related 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 for the coronavirus and wear a mask on the job.

The Biden administration was supported in the EPA court case by New York and more than a dozen other Democratic-led states, along with prominent businesses such as Apple, Amazon and Google that have called for a swift transition to renewable energy.

The administration has vowed to cut US emissions in half by the end of this decade but has floundered in its attempts to legislate this outcome, with a sweeping climate bill sunk by the opposition of Republican senators and Joe Manchin, the centrist Democratic senator from West Virginia.

The federal government also had the power of administrative regulations in order to force reductions in emissions but the Supreme Court ruling will now imperil this ability.