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Which Justices Were BFFs This Supreme Court Term

The regularly scheduled business of the Supreme Court term came to a close on Wednesday, and the nine justices will soon take off their robes and head out on their summer vacations.

The court heard major cases this year that ran the constitutional gamut: on partisan and racial gerrymandering, public-sector unions, President Trump’s travel ban, sales tax in the internet age, voting rights, politicking at polling places, sports betting, abortion, the seizure of cell phone records and discrimination against same-sex couples. In most ways, it was a firecracker term for conservatives. The court upheld the travel ban, blocked a law requiring “crisis pregnancy centers” to supply information about abortion, dealt a monumental blow to organized labor and upheld most Texas legislative maps that had been called racially discriminatory. In a few ways, though, it was a dud. The court punted a partisan gerrymandering case back to a lower court, it crafted only a narrow decision in the case of the cake baker who refused to serve a gay couple, and it offered another narrow ruling in the cell phone data case.

But no matter how you see the decisions, the latest term, like all Supreme Court terms, generated cold, hard data. Specifically, it generated data about where justices sit on the ideological spectrum and how they interact with one another. With a new justice, Neil Gorsuch, still fully settling into his seat and speculation intensifying about a possible retirement of the court’s swing voter, Anthony Kennedy, I wanted to look at the justices’ judicial relationships with each other over the last term, and what they might augur for the future of American jurisprudence.

This 2017-18 session was the first full slate of high-court cases for Gorsuch, the Trump appointee who took his seat on the bench in April 2017, more than a year after the death of the justice he replaced, Antonin Scalia. Before Gorsuch joined the court, my former colleague Harry Enten and I wrote that Gorsuch’s prior record as a judge made it likely he’d sit somewhere to the right of the conservative Scalia, and somewhere to the left of the arch-conservative Justice Clarence Thomas. In other words, Gorsuch would be a solidly right-wing justice. This is how we saw it 19 months ago:

That picture is more or less bearing out. The most prominent measures of justice ideology are called Martin-Quinn scores. After his first few cases, those scores put Gorsuch right around where Scalia was and Justice Samuel Alito is, a bit to the left of Thomas. The updated scores for the latest term haven’t yet been calculated, but it’s safe to say, given the voting tendencies of the court this term, that Gorsuch will remain in that ideological vicinity — a solidly right-wing justice who likely has decades remaining on the bench.

In lieu of those scores, for now we can simply look at which (more established) justices Gorsuch agreed with most often. At first, it seemed like Gorsuch might be even more conservative than expected: Through his first 15 cases in a partial 2016-17 term, Gorsuch sided with Thomas every single time. That streak has since been broken, but Gorsuch has still sided with Thomas more than any other single justice.

I tallied all of the justices’ votesthe opinions published on the Supreme Court’s website.

">1 — from when Gorsuch took his seat to Monday morning — and calculated how often each pair of justices agreed with one another. A few pairs of SCOTUS BFFs, eclipsing even the conservative duo of Gorsuch and Thomas, emerged from this analysis. Gorsuch and Thomas have now voted together about 84 percent of the time, but Thomas and Alito, Kagan and Breyer, and Ginsburg and Sotomayor, for example, have all voted together more often.
Supreme pairings

Percentage of agreement between pairs of Supreme Court justices since Neil Gorsuch joined the court in April 2017

Gors. Thom. Alito Rob. Ken. Kag. Brey. Gins. Soto.
Gorsuch 84% 83 81 82 61 60 57 53
Thomas 84 94 81 83 60 57 57 52
Alito 83 94 80 82 58 56 56 51
Roberts 81 81 80 91 72 72 70 66
Kennedy 82 83 82 91 72 70 70 66
Kagan 61 60 58 72 72 92 88 87
Breyer 60 57 56 72 70 92 91 90
Ginsburg 57 57 56 70 70 88 91 94
Sotomayor 53 52 51 66 66 87 90 94


None of these aggregated measures tell us anything qualitative about Gorsuch’s votes or written decisions, of course. But the flavor of the public reception has been what you might expect. “Conservatives have generally been pleased with what they have seen, while liberals say their concerns have been confirmed,” wrote the American Bar Association Journal. As ever, not everyone is happy at the same time.

What’s going on elsewhere on the bench? Some of the court’s recent cases have raised eyebrows for the strange bedfellows they’ve created. “Elena Kagan Is Up to Something,” Slate observed, noting she “crossed ideological lines at least three times” this term. What she’s up to, Mark Joseph Stern argued, is building a centrist bloc, shoulder-to-shoulder with Justice Breyer, Chief Justice John Roberts and Kennedy, and steering the court to “sensible outcomes” rather than “conservative blockbusters.” Be that as it may, Kagan still sided with her two more liberal colleagues nearly 90 percent of the time. And, of course, there are always exceptions to a simplified left-right ideological spectrum of jurisprudence. Last week’s decision on internet sales tax, for example, “defied the usual conservative-liberal lineup,” reported NPR, with Justice Ruth Bader Ginsburg joining Kennedy and the conservatives Alito, Gorsuch and Thomas. And Gorsuch and Breyer joined forces in a dissenting opinion just last week — unlikely bedfellows indeed.

Speaking of Kennedy, what is in store for the pivotal, ideologically central, 81-year-old fulcrum of the court? No retirements were announced during the court’s final day of term. Assuming he stays, the court’s tenuous, four-to-four-plus-Kennedy balance will remain. If he goes, Trump could fill the seat and create a conservative majority that could remain in tact for many years. Who knows … In May, Bloomberg wrote that Kennedy was “the focus of retirement speculation” and The Hill spoke of “a frenzy over rumors.” No one except Kennedy himself really knows, and even then maybe he doesn’t either.

Have a great summer, your honors. (Or is it yours honor?)


  1. As listed in the opinions published on the Supreme Court’s website.

Oliver Roeder was a senior writer for FiveThirtyEight. He holds a Ph.D. in economics from the University of Texas at Austin, where he studied game theory and political competition.