“It’s astonishing how little thought many past presidents put into their Supreme Court appointments. In the past, justices were often chosen for idiosyncratic personal reasons, or to please a particular interest group or voting bloc, and without much, if any, inquiry into how the nominee was likely to decide cases.
President Woodrow Wilson, for example, appointed Justice James Clark McReynolds — an awful judge and an even worse human being who Time magazine once described as a “savagely sarcastic, incredibly reactionary Puritan anti-Semite” — in large part because Wilson found McReynolds, who was US attorney general before he joined the Court, to be so obnoxious that the president promoted him to get him out of the Cabinet.
Similarly, President Dwight Eisenhower complained late in his presidency that appointing Justice William Brennan, one of the most consequential left-liberal jurists in American history, to the Supreme Court was among the biggest mistakes he made in office. But Ike’s White House never vetted Brennan for his ideological views, and Brennan was selected largely because Eisenhower was running for reelection when he made the nomination, and he thought that appointing a Catholic like Brennan would appeal to Catholic voters.
Even in 1990, after top Republican officials had published lengthy documents laying out their party’s vision for the Constitution, they still hadn’t developed a reliable system for vetting Supreme Court nominees to ensure that they were on board with the party’s agenda. Bush chose the center-left Justice Souter over other, more right-wing candidates largely due to misguided advice from his top legal advisers.
As journalist Jan Crawford Greenburg reported in a 2007 book, Souter beat out early frontrunner Ken Starr — the same Ken Starr who would go on to hound President Bill Clinton in the Monica Lewinsky investigation — in large part because Bush’s right-wing advisers feared that Starr was too liberal. According to Crawford Greenburg, then-Deputy Attorney General Bill Barr opposed Starr because of a low-stakes dispute over “a federal law that permitted private citizens to sue for fraud against the federal government.”
Much has changed since 1990. On the Republican side, the Federalist Society — a kind of bar association for right-wing lawyers with chapters on most law school campuses and in most major cities — now starts vetting law students for elite legal jobs almost as soon as they begin their studies. And Republican presidents can rely on the Federalist Society to identify ideologically reliable candidates for the bench. As Trump said in 2016 while campaigning for president, “We’re going to have great judges, conservative, all picked by the Federalist Society.”
Nor is the Federalist Society the only way Republicans vet potential Supreme Court nominees. Every single one of the Court’s current Republican members except for Barrett previously served as a political appointee in a GOP administration, roles that allowed high-level Republicans to observe their work and probe their views.
Democrats’ vetting process, meanwhile, is more informal. But it’s been no less successful in identifying Supreme Court nominees who reliably embrace their party’s stance on the most contentious issues. The last Democrat appointed to the Supreme Court who broke with the party’s pro-abortion rights stance, for example, was Justice Byron White — a dissenter in Roe v. Wade appointed by President John F. Kennedy in 1962.
The result is a modern-day Supreme Court where every single member was carefully selected by their party to ensure that they will not stray on any of the issues where the two parties have settled views. Every Republican justice voted to abolish affirmative action on nearly all university campuses, with every Democratic justice in dissent. Every Republican voted to give the leader of the Republican Party broad immunity from criminal prosecution, with every Democrat in dissent. Every Republican except for Roberts voted to overrule Roe (and Roberts merely argued that the Court should have waited a little longer), while every Democrat dissented.”
https://www.vox.com/scotus/371361/supreme-court-call-republican-justices-republicans