It’s not certain that Brett Kavanaugh will be confirmed by the Senate to sit on the Supreme Court. President Trump’s nomination of Kavanaugh on Monday kicked off a tricky midterm election year fight in which Senate Majority Leader Mitch McConnell (R-Ky.) will try to hold his caucus together to give Kavanaugh the majority he needs to be confirmed. (One bit of good news for McConnell: Every nominee since the administration of Gerald Ford has received at least one vote from the opposing party.)

For McConnell and Trump, the payoff from that effort is obvious: a Supreme Court that’s much more conservative.

The shift from Justice Anthony M. Kennedy to Kavanaugh can be visualized, thanks to data compiled by a group of academics. With Kennedy, the Court had four conservative justices, four liberal justices and one justice — Kennedy — who tended to represent the center. Kennedy voted much more conservatively in the most recent term, joining Trump’s other nominee, Neil M. Gorsuch, in 75 percent of his votes. But over the course of his service, he was generally the swing justice.


The addition of Kavanaugh, though, shifts the Court significantly to the right (or, on these graphs, upward).


This is one generalized metric, of course, and, as The Washington Post’s Robert Barnes notes, the Court’s rightward shift would probably be more staggered than sudden. But the change from Kennedy to Kavanaugh is not minor.

Another way of looking at the shift is by considering the average ideology of the court in each session. The 2016-2017 session, the first to include Gorsuch, had an average ideology about at the midpoint. A Kavanaugh court would revert it back to one that leans to the right.


That average doesn’t mean a whole lot in practice. What’s more important is where the middle justice — the one with four conservatives to his or her right and four liberals to the left — is on the ideological spectrum. With the addition of Kavanaugh, the average ideology of the conservative justices would tick up slightly — but the swing justice moves from Kennedy . . . to Chief Justice John G. Roberts Jr. In other words, with Kennedy’s departure and Kavanaugh’s arrival, Roberts would have four conservatives to his right and four liberals to his left.


During his confirmation fight under President George W. Bush, Roberts was not generally viewed as someone who would end up being the most moderate member of the Court. To put it mildly.

As our Eugene Robinson notes, there’s an additional significance to Kavanaugh’s nomination: his age. If confirmed to the court, Kavanaugh, now 53, could serve for decades. Establishing a long-lasting conservative majority has been one of the goals embraced by Trump in his judicial picks, and Kavanaugh aligns squarely with that aim.

But it also brings us back to Roberts. When he joined the Court, he was seen as staunchly conservative. Over time, his votes have moved to the center, even as the liberal justices’ votes have moved further to that pole.


There’s no guarantee, in other words, that, if confirmed, Kavanaugh’s 20th year on the bench would be as ideologically rigorous as his first.