In late June, the US Supreme Court issued a trio of landmark decisions that repealed the right to abortion, loosened gun restrictions and curtailed climate regulations. Although the decisions differed in rationale, they share a distinct trait: all three dismissed substantial evidence about how the court’s rulings would affect public health and safety. It is a troubling trend that many scientists fear could undermine the role of scientific evidence in shaping public policy. Now, as the court prepares to consider a landmark case on electoral policies, many worry about the future of American democracy itself.

Often regarded as the most powerful court in the free world, the Supreme Court sits in judgment of laws enacted by Congress and state legislatures, as well as constitutional disputes at any level of government. Its unusual power, in comparison to high courts in other democracies, derives in part from its small size and the fact that its nine justices are appointed for life, says Nancy Gertner, a retired federal judge who teaches at Harvard University in Cambridge, Massachusetts. This makes appointments both highly consequential and highly political. Partisan divisions in the US government make passing new laws difficult and adopting constitutional amendments next to impossible, meaning that the court’s word on crucial issues — such as the right to an abortion — can stand as the law of the land for a generation or more.

Evidence in the balance

The Supreme Court has been tilting to the right ideologically for more than a decade, but its political centre of gravity shifted drastically after former president Donald Trump secured three appointments, culminating with Amy Coney Barrett to replace the late liberal icon Ruth Bader Ginsburg in 2020. The result, scholars say, is an ultraconservative, six-member supermajority that is often sceptical of — if not outright hostile towards — science.

“The Supreme Court’s role in American history is a very mixed bag, but this really is different than anything we’ve ever seen,” says Wendy Parmet, who co-directs the Center for Health Policy and Law at Northeastern University in Boston, Massachusetts. “In some cases they are elevating individual rights, and in others they are dismantling individual rights, but the through line is that they are dismissive of science and the real-world impact of their decisions.”

That contrasts with several decisions in recent decades, in which the court has deferred to science and technical expertise. In one 1984 case, Chevron USA v. Natural Resources Defense Council, for instance, the court ruled that government agencies should be given latitude when interpreting federal laws, as long as their policies are reasonable and grounded in solid analysis. In a 1993 case, Daubert v. Merrell Dow Pharmaceuticals, the court tackled questions of science head on, laying out some basic principles that judges should use when evaluating evidence and expert testimony, such as making sure hypotheses are testable and evidence has been peer reviewed.

Scientific evidence has played into some high-profile issues put before the court. In 2007, for instance, the Supreme Court set the stage for modern climate regulations when it ruled that carbon dioxide, and by extension other greenhouse gases, qualify as pollutants under the Clean Air Act. And research on brain development in adolescents directly informed a series of rulings on appropriate sentencing for young people convicted of violent crimes. Roper v. Simmons in 2005, for example, found that it was cruel to impose the death penalty on individuals who were under the age of 18 at the time a crime was committed. Several cases over the next decade limited the application of life sentences without parole for juveniles.

But as the court swung to the ideological right, its attitude towards science also shifted. For neuroscientists involved in juvenile sentencing, the tide turned in 2021. Reversing the trend in earlier decisions, the Supreme Court allowed a Mississippi court to sentence Brett Jones to life in prison without conducting a mental evaluation looking at his capacity for change. Jones was convicted of killing his grandfather when he was 15 years old.

“There’s no way to argue that this decision was enlightened by science: they clearly ignored it,” says Daniel Weinberger, who heads the Lieber Institute for Brain Development at Johns Hopkins University in Baltimore, Maryland. “That’s a mindset, and that’s a reason to worry.”

A question of tradition

The prevailing theory among the Supreme Court’s current majority is known as originalism. Adherents of the theory claim to seek interpretations of the US constitution as it would have been understood when it was adopted or amended. Some historians, however, have accused the current court of cherry-picking the past to craft narratives that are incomplete, inconsistent and, at times, just plain wrong.

In its decision overturning the right to abortion in June, for instance, the court found that abortion is not “deeply rooted in the nation’s history and tradition”. Writing for the majority, justice Samuel Alito noted that the idea the constitution guarantees a woman’s right to abortion did not exist before the late twentieth century, and that abortion was illegal in every state before the court’s landmark Roe v. Wade decision conferred that right in 1973.

That assessment ignores more than a century of the nation’s early history, when abortion in the first three or four months of pregnancy was tolerated. The American Historical Association in Washington DC and the Organization of American Historians in Bloomington, Indiana, laid out this early history in a court briefing before the ruling. The briefing slammed the Supreme Court for dismissing this reality and instead adopting a “flawed interpretation of abortion criminalization that has been pressed by anti-abortion advocates for more than 30 years”.

In doing so, the court also dismissed decades of research indicating that its decision would negatively affect women’s health and increase long-standing disparities in the health system. “The court’s willingness to issue opinions that are likely to have discernible adverse impacts on the population is astonishing,” says Parmet, “and quite at odds with the long tradition of how courts have dealt with issues of public health.”

Civil service on the defensive

The court took a different tack in its latest climate case, West Virginia v. Environmental Protection Agency (EPA), which hinged on a technical question about whether the EPA has the authority to regulate the electricity sector as a whole, or just individual power plants. Siding with coal companies and Republican-led states, the court opted for the latter, ruling that if Congress had wanted to give the EPA the authority to regulate the entire industry, it would have said so.

It was not the first time in recent history that the court has challenged the authority of a federal science agency. In September 2021, the court tossed out a moratorium on housing evictions during the COVID-19 pandemic that had been issued by the Centers for Disease Control and Prevention. And in January, the justices rejected a mask mandate for major employers issued by the Occupational Safety and Health Administration. But the conservative majority went one step further in West Virginia v. EPA, and laid out a new legal test: the ‘major questions’ doctrine, which posits that agencies need explicit permission from Congress when implementing major rules.

The ruling ties the EPA’s hands at a crucial time, disregarding decades of climate science on the looming peril of global warming, says David Doniger, who heads the climate and clean energy programme at the Natural Resources Defense Council, an environmental group based in New York City.

Looking forward, Doniger expects that the EPA will respond with a different kind of regulation that is focused on the performance of individual power plants, which could also hasten the shift towards clean energy. But the major questions doctrine will reverberate through the legal system for years to come as individuals, businesses and states attempt to challenge federal rules and regulations.

It’s part of a broader trend. Republican politicians have been criticizing regulations crafted by ‘unelected bureaucrats’ for years. At the end of his tenure, Trump issued an executive order that could have stripped civil-service protection from hundreds of thousands of government employees, including scientists, so that they could be fired more easily. Biden repealed that order, but the issue remains a live wire in conservative circles.

The problem, says Blake Emerson, who studies administrative law at the University of California, Los Angeles, is that the civil service is precisely where science enters government. That’s by design: Congress does not have the expertise or the political capacity to craft detailed regulations, so lawmakers pass broadly worded laws that are often intentionally vague, leaving the details up to the experts. Now, those experts are at risk of getting squeezed from both sides — being stripped of authority and becoming more vulnerable to the whims of elected officials.

“My expectation going forward is that this court is going to limit the independence of civil servants who have scientific training, and enhance the powers of political officials,” Emerson says. “This is a dangerous moment for scientific expertise and science-informed policymaking within the government.”

Elections under the gavel

For many, however, a more pressing danger is to electoral institutions and democracy itself. At issue is a system that allows legislators in individual states to reconfigure voting districts. Politicians on both the left and right have long manipulated, or ‘gerrymandered’, district maps to their advantage — for example, by packing undesired voters together into a few oddly shaped districts so that the opposition is able to claim fewer seats in the final election.

Over the past decade, scientists have devised statistical methods to evaluate whether a given political map is fair, and the results of that work have featured prominently in numerous court cases. The question now is whether courts should be able to listen to that evidence and overrule state legislatures that have crafted gerrymandered maps.

In Rucho v. Common Cause in 2019, after hearing a challenge to gerrymandered maps in North Carolina, the Supreme Court declined to intervene. “Excessive partisanship in districting leads to results that reasonably seem unjust” and are “incompatible with democratic principles”, the court found. But it also noted that “partisan gerrymandering claims present political questions beyond the reach of the federal courts”. As such, the Supreme Court has mostly left the question of gerrymandering to state courts. But on the same day the court issued its climate ruling at the end of June, it agreed to hear a case, Moore v. Harper, brought by Republican lawmakers in North Carolina. The North Carolina Supreme Court had ruled that the maps drawn up by legislators for this year’s elections were unconstitutional, based on statistical evidence that the Republican-controlled legislature had gerrymandered the voting districts. But the legislators are now arguing that state courts should not have any authority over legislature when it comes to federal elections.

The Supreme Court could hear oral arguments in the case next month. Jonathan Mattingly, a statistician at Duke University in Durham, North Carolina, whose analysis informed the state court proceedings leading up to Moore v. Harper, is hopeful. Even in Rucho v. Common Cause, the Supreme Court did not question the statistical evidence, he says.

And in explaining why federal courts need not intervene, the court’s majority opinion specifically cited the role of state courts in overseeing redistricting disputes. At least three members of the current court, however, have voiced support for the North Carolina lawmakers’ latest claim, and at least four have voted to take the case. If the conservative majority sides with the plaintiffs in Moore v. Harper, this could remove the last judicial check on the power of state lawmakers to shape the outcomes of elections.

With 30 state legislatures controlled by Republicans, this would allow the party to manipulate federal elections, recapturing a majority in Congress and possibly the presidency, says Charles Fried, a law professor at Harvard University, who served as solicitor-general under former president Ronald Reagan. If that happens, he adds, “You would really have no way out.”

For Gertner, this is a ‘break-the-glass’ moment that should transcend partisan politics. In 2021, she served on a White House commission that evaluated how to reform the Supreme Court, and she argues that the time has come for change. There are few options, however. Introducing term limits to reduce the longevity of any Supreme Court majority would probably require a constitutional amendment. That’s impractical given partisan divisions in Congress and in the states. But enlarging the court, thereby diluting the power of the current majority, could be done legislatively, she says.

That, too, is a difficult task. Although many Democrats are calling for an immediate expansion of the court, President Joe Biden has declined to support the idea so far. Gertner remains hopeful about reform, however, arguing that the high court’s ultraconservative swing might prompt a backlash. “We are at the precipice, but I don’t think we are beyond it.”