Chief Justice Roberts has replaced Justice Anthony M. Kennedy as the member of the Supreme Court at its ideological center, and his vote is now the crucial one in closely divided cases.

Chief Justice Roberts has replaced Justice Anthony M. Kennedy, who retired in 2018, as the member of the court at its ideological center, and his vote is now the crucial one in closely divided cases. To be both the chief justice and the swing vote confers extraordinary power.
But his pivotal role on the court could be fleeting. Were President Trump able to appoint a replacement for Justice Ruth Bader Ginsburg, who is 87, or Justice Stephen G. Breyer, who is 81, the chief justice would almost certainly be outflanked by a conservative majority on his right.
And if Joseph R. Biden Jr. wins the presidency, he may have fewer opportunities to reshape the court in the short term, as the oldest member of the courts conservative wing, Justice Clarence Thomas, is 72, which is relatively young by the standards of the court.
But for now, Chief Justice Roberts assigns the majority opinion when he is in the majority, which these days is almost always. He uses that power strategically, picking colleagues likely to write broadly or narrowly and saving important decisions for himself.
In his first 14 terms, he was in the majority about 88 percent of the time. So far this term, that number has shot up to 98 percent, Professor Epstein found. Even more stunning, she said, is that Roberts voted with the majority in 96 percent of the non-unanimous decisions, compared to his average of 80 percent. This is the best showing by a chief justice since at least the 1953 term.