These decisions were controversial. Many people considered many of them wrong. But this was the nation’s Court; its decisions were rooted in the Constitution and in a shared interest in national unity.

Throughout all of this, Democratic and Republican appointees on the Court clashed, crossed, and formed coalitions. Neither those who praised it nor those who cursed it regarded the Court as the instrument of party politics.

But that idea began to fray. Opinion-writer politesse would require me to say or imply that the decay in the Court’s standing was the fault of “both sides,” or of both “right and left.”

But I cannot. It simply is not true.

One party made the Supreme Court a partisan issue. First Richard Nixon and then Ronald Reagan made attacks on the Court part of Republican Party dogma. Some will see the rejection of Judge Robert Bork by the Democratic-controlled Senate in 1987 as a product of partisanship; others may see it as one of its causes. But I think no fair-minded person could deny that a major barrier was crossed in 1991 when a Republican president, for political reasons, appointed a justice who was manifestly unqualified for the office, and who faced numerous, credible claims of sexual misbehavior as a government official. It was hard to watch the nominee testify in October 1991 without concluding that Anita Hill had told the truth and that Thomas had lied. But the administration pushed ahead regardless. This was the first major step over a dangerous threshold.

The next step came in 2000, when five Republican appointees on the Court extended its authority to decide a national election, in defiance of federal statutes, the Constitution’s text, and their own frequently expressed pieties about “our federalism.” The Court has aggressively made itself part of partisan politics, but even then, some of the justices who dissented were Republican appointees.

Partisanship sputtered for the next decade and a half. John Roberts was confirmed as chief justice with the votes of 22 Democrats––half of the party’s Senate caucus. Samuel Alito was the object of an attempted filibuster by Democrats, but was still confirmed with four Democratic votes. Sonia Sotomayor won nine Republican votes; Elena Kagan got five Republican votes and lost one Democratic vote. Justice Anthony Kennedy continued to move back and forth within the Court across partisan lines.

As the new Court settled in, people began to wonder whether the wounds of 2000 might be closing.

Then, in 2016, Justice Antonin Scalia died.

President Barack Obama, facing a Republican Senate, carefully nominated a moderate whom even Senator Orrin Hatch had previously designated as acceptable to both sides. But then the rules changed. Scalia’s seat, Senate Majority Leader Mitch McConnell said, would not be filled, no matter what. Republicans had a majority in the Senate and could use it for any purpose they wished—including making the Supreme Court seat a plum partisan patronage job to be filled after the next presidential election. Republican nominee Donald Trump assured Republican voters that he would appoint justices who would “automatically” overturn Roe v. Wade. To make this clearer, he released a short list of nominees, in effect putting their names on the presidential ballot besides his. Another threshold was crossed: A Court seat was a partisan prize, its holders subject to popular vote.