New top story from Time: How Amy Coney Barrett Could Alter the Future of the U.S.’s Climate Change Policy

The death of Justice Ruth Bader Ginsburg and President Trump’s quick nomination of Judge Amy Coney Barrett has escalated an already-tense political environment in the U.S., shaking up the presidential campaign and animating activists across the political spectrum. A remade Supreme Court populated by Trump appointees threatens to overturn abortion rights, roll back voter protections and scrap the Affordable Care Act.

The future of the Court will also shape the future of U.S. climate policy. A Supreme Court remade in the vision of the right could take aim at existing climate change measures—and the legal justifications underpinning them—while also impeding the ability of federal government agencies to implement new ones. At the heart of the issue is the role of federal agencies and their ability to regulate, an area known as administrative law. In the U.S. at least, it’s hard to conceive of a comprehensive climate-fighting regime that doesn’t rely on agencies to play a role regulating emissions. Conservative jurists are generally skeptical of these powers, and it’s likely a more conservative Supreme Court would seek to limit them.

That wouldn’t necessarily doom future presidential or legislative attempts at creating new and more stringent climate rules, but it’d make it all a lot harder. “It’s not a death knell,” says Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University. “But it’s going to require great care by Congress and the [next presidential] administration to avoid these problems.”

How agencies became so important

For the uninitiated, administrative law can sound esoteric, but it has played a central role in creating our current climate protections. Some issues are too complicated to be solved by Congress alone, so Congress has in many cases passed laws that create a broad framework but leave the implementation up to federal agencies. In the environmental space, that history dates back to the 1970s: Congress passed the Clean Air Act and the Clean Water Act to address rampant pollution in the U.S, and the Environmental Protection Agency administered the laws.

Climate change wasn’t included in the original mandate of the EPA, and Congress has never explicitly told the agency to regulate greenhouse gas emissions, but as global warming science grew increasingly alarming, the agency was forced to incorporate reducing greenhouse emissions into its mandate. Troubled by the federal government’s inaction, a group of states led by Massachusetts sued the EPA in 2006 to demand the agency act to reduce emissions. The following year, the Supreme Court ruled in a 5-4 decision known as Massachusetts vs. EPA that the agency needed to regulate greenhouse gas emissions if EPA scientists found they endangered human health. The Court’s decision meant that combating climate change was, effectively, a responsibility of the executive branch.

Thanks to that ruling, the EPA became the primary regulator of greenhouse gas emissions in the U.S. When President Barack Obama failed to pass climate legislation through Congress in 2009, he turned to the agency and others to create new rules using the Clean Air Act and other existing law. Almost all of the significant climate measures enacted under President Obama—think the Clean Power Plan, vehicle emissions standards and methane rules—came via one of the federal agencies

Trump came to office keen to undo these regulations, and his Administration has spent the last four years using its authority to push agencies to move climate policy in reverse. In total, Trump has sought to roll back some 100 environmental rules, according to a New York Times count last updated on July 15. “There has been nothing like this administration on the environment in the last 50 years,” says William Reilly, who headed the EPA under George H.W. Bush, referring to what he called Trump’s “general dereliction” of duty to protect the environment.

But while Trump has sought to tear up the country’s climate regulation, his efforts have been met with major challenges. Because Massachusetts vs EPA still stands, the administration is still technically responsible for fighting climate change, and his rollbacks need to show sound legal and scientific reasoning—which can be hard to come by given Trump’s primary motivation has little to do with science or law. This reality has tied up many of his deregulatory moves in the courts. The administration has only succeeded in 15 of the 87 attempted rollbacks that have been litigated, according to data from the Institute for Policy Integrity.

If a more conservative Supreme Court decides to revisit Massachusetts vs EPA, the result could make it significantly easier for Trump or a future president to eliminate these rules—and hinder the ability for a new administration to make new rules. There are multiple scenarios that could play out over the coming years.

What comes next

Biden has telegraphed repeatedly that he plans to make fighting climate change a top priority if he defeats Trump in November: he has called for the U.S. to hit net zero emissions by 2050 and eliminate the carbon footprint of the power sector by 2035. What kinds of measures he could actually enact to reach those goals will depend significantly on the composition of the Supreme Court.

If Biden wins without a Congressional majority, he would likely struggle to pass legislation through a divided Congress and, like Obama, would need to turn to agencies to make rules in the absence of a new law. A Biden EPA would likely try to implement all sorts of emissions-reduction measures, using the Clean Air Act as its justification.

But conservative jurists have already indicated how they would fight that. In 1984, the Supreme Court created a precedent known as “Chevron deference,” which gave agencies leeway to interpret laws passed by Congress if they deal directly with the agency’s work. So, in this case, the EPA is given significant deference to interpret the Clean Air Act. Conservatives have criticized that practice since the beginning, and Justice Brett Kavanaugh, who could be the new swing vote on the Court, has criticized it. The doctrine “can be antithetical to the neutral, impartial rule of law,” Kavanaugh wrote in 2016. Moreover, the Supreme Court could overturn or significantly weaken Massachusetts vs EPA, and the practice of using agencies to address climate change would be vulnerable to legal challenge or foreclosed entirely.

In theory, a Democratic majority in both houses of Congress would fix this problem. Congress could pass a law that requires the EPA to regulate emissions, effectively bypassing Massachusetts vs EPA. Or Congress could create a different regulatory framework entirely.

But conservative jurists are one step ahead of such measures. For decades, conservatives have touted a principle known as the “nondelegation doctrine,” which rejects Congress’s ability to give too much power to agencies. Conservatives have had limited success using that argument in court thus far, but that could easily change if the Supreme Court shifts ideologically. And it could effectively prevent new climate laws that require an agency like the EPA for implementation.

“The reshaping of the judiciary under the Trump Administration toward a right-leaning judiciary that is not only willing but eager to shrink the administrative state is simply not compatible with strong regulation of anything,” says Cara Horowitz, executive director of the Emmett Institute on Climate Change and the Environment at UCLA School of Law.

Finally, there’s a very real chance that Trump ends up in office for a second term. In that case, it’s safe to assume that the federal judiciary and the Supreme Court would continue its conservative bent, chipping away at the power of agencies to address climate change. That would aid in Trump’s ongoing rollbacks and grind even the currently insufficient climate policies to a halt.

Fighting back

A hard right turn by the Supreme Court—not to mention the impact of the hundreds of federal judges Trump has appointed to lower federal courts—would clearly pose deep challenges for a Biden Administration, but that doesn’t mean it couldn’t fight back.

Environmental lawyers say if Democrats control Congress, they would need to craft very explicit climate laws that can’t be interpreted as delegating too much authority to agencies to avoid legal challenges. Perhaps more importantly, Horowitz says, Democrats might want to consider how they can reshape the judiciary more broadly to avoid the near-impossible challenges created by conservative jurists. “Rather than trying to shape your policy to match the current Court,” says Horowitz, “maybe figure out a way to shape the judiciary to match what you want to do with your policy.” In other words, the ongoing discussions about whether a potential Biden Administration should try to expand and pack the Supreme Court matters a lot for the course of climate policy.

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A version of this article was originally published in TIME’s climate newsletter, One.Five. Click here to sign up to receive these stories early.