Throughout the 2016 presidential campaign, both liberals and conservatives hoped that their candidate could shift the direction of the Supreme Court by appointing justices willing to knock down high-profile decisions that have profoundly shaped social policy. Now, President Trump is aiming to do just that, nominating federal appeals court judge Neil Gorsuch, a conservative straight out of Republican central casting, to fill the seat once held by Antonin Scalia. Given the age of the justices on the court’s liberal wing, Trump will likely get to appoint more than one justice, leading many observers to anticipate that historic liberal decisions such as the 1973 ruling in Roe v. Wade, which affirmed abortion rights, are facing a new and serious threat.

An outright reversal of Roe would be a dramatic move for the nation’s highest court, in no small part because the decision has been the foundation of abortion law and policy for four decades. But by sanctioning abortion restrictions that the court might have struck down in the past a strongly conservative court could gradually narrow Roe’s scope, thereby limiting access to abortion while leaving the decision technically intact.

The fate of signature liberal rulings like Roe won’t depend just on Trump’s nominees’ political ideology, but also on their judicial philosophy, especially their approach to precedent. Respect for precedent is a foundational legal concept that asks judges to take past decisions into account when they rule on related cases. In practice, this means that when the Supreme Court justices hear a case that deals with issues such as abortion or the death penalty, deference to precedent generally leads them to render a decision that’s in line with prior decisions on the issue. But adhering to precedent isn’t just a yes-or-no proposition; precedents can be narrowed or enlarged or clarified, or they can be shifted through a series of decisions that slowly change the way a ruling is applied by the lower courts.

In a legal system where judges are often unelected and can serve lifetime terms, the appeal of precedent is obvious: It promises certainty and continuity, and it guards against the whims of a handful of judges who decide they don’t like the rules. But precedent is also not, as Chief Justice William Rehnquist observed in 1991, “an inexorable command.” Since 1810, when the Supreme Court first broke with precedent, the justices have overruled their predecessors more than 250 times — that is, the justices explicitly acknowledged a change to precedent, whether in a majority opinion or a dissenting opinion.

These reversals, however, are only a tiny fraction of the thousands of cases that the Supreme Court has heard over the years. A look at the numbers from the Supreme Court Database, an online clearinghouse for data about the court, shows that although a few precedents are generally altered each term, that doesn’t mean the Supreme Court will change a precedent on a dime. Since 1953, when Earl Warren took over as chief justice, the court has altered precedents in just over two percent of cases. The court’s willingness to overturn precedent can also ebb and flow: In the 1955 term, early in Warren’s time on the court, no precedents were altered, but in the 1962 term, the justices changed precedent in just under four percent of their cases, including in a landmark decision establishing the right to an attorney for defendants who can’t afford one, overruling a 20-year-old precedent.

The relative rarity of breaks with precedent would seem to spell bad news for any court-watcher — liberal or conservative — hoping for an immediate shift in the Supreme Court’s approach. Even if Gorsuch proves open to breaking with precedents, that might not represent a significant change, because Scalia himself was quite willing to depart from precedent in his quest to deliver decisions that he felt were more closely in line with the original meaning of the Constitution. Scalia rarely dissented when precedent was changed: In the precedent-altering decisions that came down during his time on the bench, Scalia voted in the majority 82 percent of the time. Even in some cases where he agreed with the outcome — including in a 2014 decision that struck down a Massachusetts abortion-protest law — Scalia scolded his fellow justices for not attacking an underlying precedent.

It’s a little hard to know what Gorsuch’s approach to precedent would be (although he has expressed suspicion about an important precedent that requires courts to largely defer to federal agencies about how the bureaucracies’ responsibilities are defined), but it’s safe to say that he won’t be a threat to Scalia’s legacy: A group of academics and lawyers recently concluded that Gorsuch is the most Scalia-like of the three candidates who were reportedly on Trump’s short list for the job. Gorsuch’s influence could also extend beyond his own vote: He once clerked for Justice Anthony Kennedy, who often serves as the court’s swing vote, so he might be able to convince Kennedy to join more conservative majorities.

Precedents — and the court’s willingness to set them aside — can cut both ways ideologically.

Under Warren in the 1950s and 1960s, nearly all alterations of precedent resulted in a more liberal ruling, with decisions in favor of criminal defendants, environmental regulations, unions or civil rights claimants. Since then, the court has moved to the right: Despite a small spike in left-leaning precedent changes in the past few years, 63 percent of the Roberts court’s precedent-altering decisions have been conservative.

The Roberts court is already showing signs that it may be willing to rethink signature liberal rulings. Other chief justices — Warren, for example, in the lead-up to the 1954 Brown v. Board of Education school-desegregation case — worked to build large (or even unanimous) majorities to overturn established precedents. Chief Justice John Roberts also prizes unity and consensus, but on his court, the share of precedent-changing cases decided by a slim one-vote majority is higher than it has been under any other chief justice. That suggests that the current court may be more willing to start chipping away at precedent, according to Lee Epstein, a professor at Washington University and a contributor to the Supreme Court Database. “Overruling can tell you something, but not the whole story,” she said.

Still, the real threat to liberal precedent would come if Trump has the opportunity to replace a member of the aging liberal vanguard. That, more than the Gorsuch nomination, would tilt the ideological balance of the court toward the conservatives. But even then, change could be gradual, said Jeffrey Segal, another Supreme Court Database contributor and a political science professor at Stony Brook University. “They might not overturn a precedent right away, but they start chipping away at it until they can say, ‘Look, this precedent just isn’t workable and it’s time for it to go,’” he said. In the case of Roe v. Wade, this might mean upholding a series of state-level restrictions on abortion, until the original precedent is eventually overwhelmed. “It’s not overruling a decision so much as eviscerating it,” Segal said.

In other cases, the justices don’t need to formally overrule precedent to render a historic decision unusable. Barry Friedman, a professor of law and politics at New York University, argues that over the course of several decades, the court systematically undermined its landmark 1966 ruling in Miranda v. Arizona without ever formally reversing it. Friedman said justices were aware of the backlash they would face they reversed the now-iconic ruling requiring police to read defendants their rights. “My hypothesis is that the court doesn’t want to take heat where it doesn’t need to take it,” he said. In 2000, after the court heard a case designed to take down Miranda, Rehnquist wrote a majority opinion where he declared that the Miranda warnings had become “part of our national culture.” This decision, Friedman says, was followed almost immediately by cases effectively inviting police to ignore the Miranda ruling.

Public perceptions of the court’s ideological orientation also affect the types of cases that make their way to the Supreme Court and can influence the way those cases are argued in the lower courts, Epstein said. In a study published in 2015, Epstein found that the Roberts court was substantially more likely to overrule a precedent if they were asked to do so by one of the parties in the case.

“If Trump is able to appoint more than one justice to the court, they’re not going to start overruling precedents overnight,” she said. “But let’s face it, the whole legal system will start to tilt. Lower courts will start rationally anticipating a more conservative Supreme Court. Lawyers will start banging away at precedents. And all of this hydraulic pressure can lead the court to conclude that a particular precedent is unworkable.”





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