This week, the Senate Judiciary Committee starts its controversial hearings on President Trump’s most recent nominee for the United States Supreme Court, Judge Amy Coney Barrett. Before Justice Ruth Bader Ginsburg died last month, the Supreme Court had five conservative Republican appointees and four liberal Democratic appointees. If Barrett is confirmed, her presence would shift this 5-to-4 division to 6-to-3 — meaning that it will no longer be possible that, if a single conservative justice defects, a more liberal point of view could prevail.

How might this larger conservative majority affect public perception of the court, even if the court’s overall ideological trajectory stays roughly the same? Research suggests an immovable conservative bloc might undermine the court’s legitimacy.

Here’s how I did my research

My research looks at the public’s reactions to Supreme Court division in the era of partisan polarization among the justices. Historically, the court tried to find larger majorities to legitimize its decisions. Until the mid-20th century, dissenting opinions were rare; chief justices encouraged their colleagues to present a united front even when there was internal disagreement. Even after that norm had eroded, Chief Justice Earl Warren famously lobbied his colleagues for a unanimous decision in Brown v. Board of Education — even though only five planned to vote to find school segregation unconstitutional — because he feared a dissenting opinion would fuel resistance from White Southerners. More recently, Ginsburg told an audience at Duke Law School, “I don’t think that the 5-to-4 decisions have the same clout as a unanimous decision.”

Apparently, they were wrong. That’s what I found when I tested this idea with a survey experiment. In January 2011, with the help of YouGov, I interviewed a nationally representative sample of 600 people. I asked the survey respondents to read brief reports of (fabricated) Supreme Court decisions. Some read that these (fictional) cases were decided by large majorities, while others read about the same cases decided by narrow majorities. Afterward, I asked respondents, “Do you think that the decision ought to be accepted and considered to be the final word on the matter or that there ought to be an effort to challenge the decision and get it changed?” I then looked at whether the size of the majority affected their answers.

It did sometimes, depending on the issue involved. For instance, when told that the court had ruled 8-to-1 or 9-to-0 on something that roused few passions, like contract disputes, those who disagreed with that ruling were less likely to say they would work to overturn the outcome than those told the case was decided 5-to-4. But when the issue was a cultural hot-button issue — in this case, marriage equality — those opposed to the outcome were just as likely to say they’d work to overturn it whether they believed it had been decided by a narrow or large majority.

Interestingly, when the issue was something more in-between — in this case, employee privacy — opponents were more likely to accept the decision if one or more justices had written dissents, no matter the majority’s size.

That last result may seem surprising, but it’s consistent with social psychology’s theories of procedural justice. In short, whether the loser in a legal dispute accepts that loss depends in large part on whether the loser thinks the process of getting to that decision was fair. Those opposed to a Supreme Court ruling may be more willing to accept it if they see evidence that both sides were fairly heard. Dissent may be that evidence.

What does that mean for Americans’ belief in the court’s legitimacy?

Because the majority’s size does not negatively affect the public’s acceptance of Supreme Court rulings, we might not expect them to respond any differently to 6-to-3 rulings than 5-to-4 rulings. Liberals may conclude that my research suggests the damage on the most visible cases is done on the fifth conservative vote, with nothing added or taken away by the sixth. But I conducted my research at a time when there were five justices appointed by Republicans and four by Democrats — and one of those Republican-appointed justices, Anthony M. Kennedy, would semi-frequently side with the liberal wing. The result was a court that leaned slightly conservative but occasionally delivered liberal victories on high-profile issues.

But Kennedy has been replaced by hard-line conservative Brett M. Kavanaugh, making Chief Justice John G. Roberts, a more reliably conservative vote than Kennedy, the closest thing to a “swing” justice on the current court. If Barrett replaces Ginsburg, those occasional swings would likely disappear. A court with permanent winning and losing coalitions might well change public perceptions.

In other words, an immovably 6-to-3 conservative court might erode public confidence in the institution itself. Political scientist James L. Gibson and his colleagues have found that the court’s popular legitimacy remains durable — and that even the infamous Bush v. Gore decision did little to shake citizens’ faith. Attitudes toward the court, they find, are shaped not by satisfaction with its decisions but by support for core democratic values — and the American people are fine with the idea that judges’ ideologies influence their decisions. However, Gibson and colleagues also find that once Americans begin to see the court as overtly politicized and the justices as nothing more than ordinary politicians in robes, they have less confidence in the court’s legitimacy and decisions. If a 6-to-3 court ushers in an era of unwavering, predictable conservative victories and liberal losses that Americans view as not just an ideological leaning but part of a strategic, partisan battle, the court’s standing may falter.

Michael F. Salamone (@enomalas) is an associate professor of political science at Washington State University and author most recently of “Perceptions of a Polarized Court: How Division Among Justices Shapes the Supreme Court’s Public Image” (Temple University Press, 2018).