Judge Ketanji Brown Jackson has the chance to make history as the first Black woman to sit on the Supreme Court, if she’s confirmed. But if she is, she’ll also bring another kind of diversity to the court: religious diversity.
As a nondenominational Protestant, Jackson, if confirmed, will join a court that is currently composed entirely of Catholics and Jews — groups that make up only 23 percent of the general population. The Senate hasn’t confirmed a Protestant to the court since 1990.
Does this mean that the public should expect Jackson to make different decisions than her non-Protestant peers? My research suggests no. Federal judges’ personal religious affiliations don’t much influence how they decide cases about religion.
No religious tests? Not so fast.
Although the U.S. Constitution famously forbids the use of any “religious test” in the confirmation process, senators have long pressed Supreme Court nominees about their religions, often in an effort to glean their views on hot-button issues such as abortion or same-sex marriage.
This happened with Justice Amy Coney Barrett, the Republicans’ most recent appointee. And harking back to those hearings, on Tuesday, Sen. Lindsey O. Graham (R-S.C.) asked Jackson to rate her religious faith “on a scale of 1 to 10” and mused whether she would be able to fairly judge a Catholic litigant.
Most legal scholars agree that questions like these are only appropriate if they’re motivated by a sincere desire to illuminate a judge’s latent ideological, rather than religious, commitments. After all, the institutional purpose of the confirmation process is to preserve the judiciary’s legitimacy by weeding out partisan judges who might be judicially inexperienced or biased.
So if religious judges behaved differently from nonreligious ones — if religious judges harbored a “dogma,” as Sen. Dianne Feinstein (D-Calif.) once put it — then there could be valid reasons to be concerned about the religious makeup of the court.
But recent political science research suggests that religion does not influence judges’ decision-making, as many people fear it does.
How that research works
To study the ways that judges make decisions, quantitative scholars often look at many cases over time. They then use the random assignment process on the federal appellate circuits to draw causal inferences — or, in other words, they view the decisions as the results of a naturally occurring experiment. That’s what I did in my research, as part of a team of co-authors. We examined every religion-related Title VII case decided by the U.S. courts of appeals from 2000 to 2020. These cases posed questions about how and when workplaces should accommodate religious practices.
Our theory was that if religion were affecting judicial decision-making at all, it would be easiest to spot it in situations where a litigant’s own religious beliefs were directly at stake.
Is there really any “dogma”?
Our research found no evidence that religion had any aggregate influence on the more than 300 judges in our data set. If anything, judges of some Protestant groups — specifically those that were evangelical or nondenominational, like Jackson — tended to be less sympathetic toward litigants bringing free-exercise claims, not more.
Complicating this dynamic, though, we also found evidence that Black judges — also like Jackson — exhibited the opposite behavior. This bolsters the view that a judge’s race, if not their religion, often influences their decision-making.
But we studied only private “free exercise” cases, or cases akin to those based on the constitutional clause that the government will protect the “free exercise of religion.” In these cases, judges rule on whether individuals can practice their religions unencumbered or whether they are constrained by other rights and regulations. For instance, the Supreme Court’s 2020 case Fulton v. Philadelphia was a “free exercise” case. In it, justices decided whether the city of Philadelphia could refuse to contract with Catholic Social Services for foster care placements, because the organization would not place children with same-sex couples — in violation of the city’s anti-discrimination laws.
We did not look at “establishment” cases, or cases about the constitutional clause banning the government from establishing any religion. In these cases, judges rule on how much the government can constitutionally endorse or reject religion. For instance, in Carson v. Makin, recently argued before the Supreme Court, the justices will decide whether the state of Maine can constitutionally fund sectarian schools with public tax dollars.
However, scholars Sepehr Shahshahani and Lawrence J. Liu published a 2017 study of federal establishment cases, and they also found minimal evidence for the influence of religion. They determined that only Jewish judges were more likely to decide cases differently and that they were more likely to uphold the separation of church and state, not less.
Discussing religion as a political signal
Since little evidence supports the view that judges are influenced by their religions, at least in cases directly about religion, it doesn’t make much sense for senators to focus so much on nominees’ religions — at least if they are truly motivated by concerns about judicial legitimacy.
Senators may be using discussions of religion as an opportunity to score political points instead, either catering to their voting base, or, in Graham’s case, striking back at perceived injustices by the Democrats in previous confirmation battles. They also may simply be using religious vetting as a way to challenge nominees’ beliefs about other politically important questions, like those involving abortion or same-sex marriage.
Some observers, like Justice Elena Kagan, accordingly see confirmation hearings as a kind of “vapid and hollow charade.” But other research suggests that political grandstanding during Supreme Court confirmation hearings is one way senators try to represent their constituents.
The focus on nominees’ religion is likely one aspect of this distinctive form of politics. While Jackson’s Protestant background would diversify the court, there’s little evidence that it would influence her judgment of religious freedom.
Matthew Dahl holds an MA in political science from the University of Notre Dame and is currently a Fair Housing Fellow at Brancart & Brancart.
Note: Updated Oct. 5, 2023.