Sometimes what’s remarkable is what goes unremarked upon. In all the pieces already written about the impending fight to confirm Associate Justice Anthony M. Kennedy’s as-yet unpicked successor on the Supreme Court, no one has so much as suggested that anything besides partisanship and ideology will matter. Credentials? Qualifications? Scandal? Racial, ethnic and gender diversity? All of these considerations, so prominent in judicial appointment debates for decades, are largely irrelevant. It’s pure politics now, and no one pretends otherwise.

Today’s partisanship culminates an astonishing transformation. It’s hard to recall now, but for most of the last century almost nobody would admit to voting for or against a nominee because of his or her partisan affiliation. In fact, although opposing judicial nominees was not uncommon in the 19th century, between 1894 and 1968, the Senate rejected just one presidential nomination to the high court. Deference to presidential prerogative prevailed.

Supreme Court nominations did get more contentious, and more political, in the second half of the 20th century—but for a long time the pretense of an apolitical process remained. By the 1960s, the liberal activism of the court under Chief Justice Earl Warren—desegregating schools, prohibiting prayer in school, expanding the rights of the accused—spurred conservatives to go after President Lyndon Johnson’s nominees. In 1967, Southerners—the main critics of the court’s jurisprudence—discarded the tradition of deference to the president in challenging the choice of Solicitor General Thurgood Marshall to be the first black justice. Notably, though, instead of admitting they opposed Marshall because of racial politics, they denigrated his intellect and legal bona fides—suggesting that qualifications, not ideology, were what mattered. Strom Thurmond of South Carolina ostentatiously grilled the legendary NAACP lawyer on how the 14th Amendment was drafted. When Marshall couldn’t deliver certain facts, Thurmond piously deemed him unqualified for the court. The ugly hazing didn’t stop Marshall’s appointment, of course, but eleven senators voted against him, all from Southern or border states.

A replay of sorts came the next year, when LBJ picked his friend Abe Fortas, already an associate justice, to replace the retiring Warren as chief. Conservatives again rebelled. Fortas’s liberalism was obviously the issue; Richard Nixon was targeting the Warren Court’s jurisprudence in his presidential campaign. But norms still frowned upon rejecting a justice on strictly ideological grounds, so Fortas’s detractors cloaked their opposition in talk of ethics and merit. The justice had taken $15,000 to run some seminars at a local university, and his critics hyped this petty offense into a disqualifying crime. On the Senate floor, an alliance of Republicans and Southern Democrats staged a four-day filibuster, forcing Johnson to withdraw the nomination and leaving the seat open for the next president. Nixon, of course, won.

The Democrats kept the Senate, however, and soon it was payback time. After a surreptitious White House campaign helped force Fortas off the bench under a cloud of scandal, the Democrats struck back. To replace Fortas, Nixon chose an anti-civil rights strict constructionist, Clement Haynsworth of South Carolina from the fourth circuit federal appellate court. Instead of citing Haynsworth’s reactionary politics, Democrats homed in on ethical missteps he’d made in the past, like failing to recuse himself in cases involving companies in which he owned stock. Those conflicts of interest sank his nomination. Democrats rejected Nixon’s next choice, too, G. Harrold Carswell of Florida—again, not by branding him too conservative but by digging up racist statements in his record, along with a case of his having helped transfer a public golf course into private hands in order to avoid desegregating it. ...