Jason Richwine writes for National Review Online about the pivotal role of one of the U.S. Supreme Court’s newest members.

If Justice Barrett votes as her mentor Justice Scalia did, she will be part of an ascendant conservative majority on the Supreme Court. What kinds of decisions can we expect from this majority? Short answer: Ask Brett Kavanaugh.

Contrary to how journalists frame each seat change on the Court, comparing the new justice to the departed one is not the best way to assess the impact. Instead, we should determine who becomes the median (or swing) justice, meaning the justice who provides the crucial fifth vote when a case splits the Court ideologically. Two years ago, Kavanaugh’s appointment shifted the median from the retiring Justice Kennedy to Chief Justice Roberts. As I noted at the time, exactly where Kavanaugh fit in among his conservative peers didn’t matter much. As long as he stayed somewhere to the right of Roberts, then Roberts would dictate the outcomes.

I also noted, however, that if Justice Ginsburg were to be replaced by a conservative — I called this mystery nominee “Amy B.” — then Kavanaugh’s exact ideological position would become very important. If he turned out to be a near-clone of Roberts, then the median would not change, and “Amy B.” would have surprisingly little impact on the Court’s decisions. By contrast, if Kavanaugh established himself as a solid conservative vote, then a Ginsburg exit could shift the Court’s median well to the right.

During his two years on the bench, Kavanaugh has been a cautious conservative. He is sometimes unwilling to issue decisions that are as far-reaching as fellow conservatives Gorsuch, Alito, and Thomas would prefer. At the same time, Kavanaugh has separated himself from Roberts by sticking with conservatives on big cases in which the chief “defects” to the liberals.