One of Justice Antonin Scalia’s final acts before his death in 2016 was also one of his most breathtaking: joining with four other conservative justices to block implementation of the Clean Power Plan, then president Barack Obama’s ambitious effort to regulate carbon emissions from coal-fired power plants ahead of the Paris climate agreement. That decision was unprecedented not just because the justices didn’t bother to explain their reasoning, but also because the high court had never before stopped a regulation dead in its tracks as legal challenges to it were pending, let alone in an area of federal policy that could likely make or break the planet.

The Supreme Court looks vastly different today than it did six years ago, but as its conservatism has grown more pronounced, so has is its antipathy toward good government, administrative agencies, and federal efforts to make our country’s laws—to borrow one phrase from retiring Justice Stephen Breyer—work for its people. And on Thursday, on the final day of an already historic, cataclysmic term that saw the end of nearly five decades of jurisprudence protecting the right to abortion and other judicial overreach, six justices on the Supreme Court finished what five began at the dawn of the prior Democratic administration: They defanged the Environmental Protection Agency’s power to curb carbon pollution under the federal Clean Air Act, in a near-fatal blow to the government’s rulemaking authority to ensure the air we breathe is a little safer and the impacts of climate change blunted.

The particulars of the legal issues decided in West Virginia v. EPA are wonky and steeped in the language of administrative law. But the heart of the dispute is rather simple: How specific do laws delegating the authority to fix a complex, generational problem affecting all Americans to the president and his administrative agencies have to be? In Section 111 of the Clean Air Act, Congress empowered the EPA to take measures to get at the root of sources of any substance that “causes, or contributes significantly to, air pollution” that “may reasonably be anticipated to endanger public health or welfare.” And because carbon dioxide and other greenhouse gasses are covered by that definition, the EPA is a sort of regulator in chief for greenhouse emissions from fossil fuel-fired power plants. According to the EPA, those plants produce about a quarter of the nation’s greenhouse emissions.

Because that mandate to ensure the nation’s air is breathable is clear, Obama’s Clean Power Plan sought to regulate power plants under it and nudge them from dirty, fossil fuel-reliant sources of energy, like coal, to cleaner ones, including natural gas, solar, and wind energy—with these last two sources taking precedence. That plan was not to be: A number of Republican-led states, industry groups, and coal companies sued to block its implementation, and the rest is Supreme Court history: Scalia, Chief Justice John Roberts, and justices Anthony Kennedy, Clarence Thomas, and Samuel Alito blocked it from taking effect. By the time the Trump administration came around and rolled back the plan, its ambitions never materialized. And so it’s not binding on anyone. And the Biden administration is in the process of formulating a more modern, capacious rule, but it’s not final yet.

So where does this leave this “restless and newly constituted” Supreme Court, as Justice Sonia Sotomayor called her reactionary colleagues a few weeks ago? Precisely where one might predict, deciding the issue anyway—and hobbling the way the EPA can conduct unfinished work. To this majority, curbing carbon dioxide emissions at power plants is simply not something the federal government can do under existing law. If Congress wants the EPA to go that route to help slow down global warming, lawmakers just need to give that authority much more specifically than they did all those years ago with the Clean Air Act. “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 wrote for the majority.\

The three liberal justices, as they did when their counterparts ruled that the Biden administration’s labor secretary and occupational safety regulator didn’t have the authority to impose a vaccine-or-test requirement on large employers, saw right through this power grab. Long an expert in administrative law, Justice Elena Kagan, joined by Sotomayor and Breyer, put the court’s overstep in its proper light. “The Court today issues what is really an advisory opinion on the proper scope of the new rule EPA is considering,” she wrote. “That new rule will be subject anyway to immediate, pre-enforcement judicial review. But this Court could not wait—even to see what the new rule says—to constrain EPA’s efforts to address climate change.”

In the law, at least before this case, an advisory opinion is presumptively unconstitutional because federal judges, including Roberts and his comrades, may only entertain actual “cases” or “controversies.” That’s bad enough. Even Roberts, in his own majority opinion, takes notice that Kagan is accusing him of “champing at the bit.” But the bigger sin of West Virginia v. EPA is that the Supreme Court isn’t just hobbling an agency, an administration, or even a president wishing to respond to a pressing issue of national importance. Six justices, in so many words, are so unsympathetic to the idea of public servants acting in the best interests of the nation, through regulations that arise from clear congressional authority, that they’re declaring war on Congress’s own ability to do its job.

Congress, after all, told regulators to choose the “best system of emission reduction.” And if that doesn’t mean power plants that don’t contaminate the planet, then what does? As Kagan writes, “The ‘best system’ full stop—no ifs, ands, or buts of any kind relevant here.” She rightly focuses her darts on the Roberts court, as well as Justice Neil Gorsuch, who has long evinced an anti-regulation streak, to note that its larger agenda is to dismantle the administrative state. “Today, one of those broader goals makes itself clear,” she writes. “Prevent agencies from doing important work, even though that is what Congress directed. That anti-administrative-state stance shows up in the majority opinion, and it suffuses the concurrence” by Gorsuch.

Her words here are one of a piece with prior writings where she’s sounded the alarm on the Supreme Court’s wild deregulatory ambitions. If in January that meant taking aim at public health efforts to protect us from a pandemic, and this week that means taking aim at climate change regulations, going forward that could mean torpedoing agency efforts to regulate the internet, the workplace, the financial sector, or various industries where abuses are rampant. And there’s no telling how much power the Supreme Court is arrogating to itself in the face of a Congress where Joe Manchin, a longtime friend of the coal industry, holds the keys to Biden’s climate agenda. “The Court, rather than Congress, will decide how much regulation is too much,” Kagan wrote.

Kagan isn’t one for hyperbole, and over the years she has sought collegiality and compromise with other justices, especially those on the conservative side. But if her laments here are an indication, she may have reached the point where she’s done playing nice. “The subject matter of the regulation here makes the Court’s intervention all the more troubling,” she writes in the closing paragraph of her dissent. “Whatever else this Court may know about, it does not have a clue about how to address climate change. And let’s say the obvious: The stakes here are high. Yet the Court today prevents congressionally authorized agency action to curb power plants’ carbon dioxide emissions. The Court appoints itself—instead of Congress or the expert agency—the decision-maker on climate policy.”