The Editorial Board – The New York Times.

Soon after his inauguration next month, President-elect Donald Trump will nominate someone to the Supreme Court, which has been hamstrung by a vacancy since the death of Justice Antonin Scalia in February. There will be public debates about the nominee’s credentials, past record, judicial philosophy and temperament. There will be Senate hearings and a vote.

No matter how it plays out, Americans must remember one thing above all: The person who gets confirmed will sit in a stolen seat.

It was stolen from Barack Obama, a twice-elected president who fulfilled his constitutional duty more than nine months ago by nominating Merrick Garland, a highly qualified and widely respected federal appellate judge.

It was stolen by top Senate Republicans, who broke with longstanding tradition and refused to consider any nominee Mr. Obama might send them, because they wanted to preserve the court’s conservative majority. The main perpetrators of the theft were Mitch McConnell, the majority leader, and Charles Grassley, chairman of the Judiciary Committee. But virtually all Republican senators were accomplices; only two supported holding hearings.

The Republican party line — that it was an election year, so the American people should have a “voice” in the selection of the next justice — was a patent lie. The people spoke when they re-elected Mr. Obama in 2012, entrusting him to choose new members for the court. And the Senate has had no problem considering, and usually confirming, election-year nominees in the past.

Of course, Supreme Court appointments have always been political, and the court’s ideological center has shifted back and forth over time. But the Senate has given nominees full consideration and a vote even when the party in power has opposed a president’s choice. That is, until this year, when Republicans claimed that though the Constitution calls for the Senate’s “advice and consent,” senators aren’t obligated to do anything. This is a bad-faith reading of that clause, even if there is no clear way to force a vote. It certainly obliterates a well-established political norm that makes a functioning judicial branch possible. As Paul Krugman wrote in his column on Monday, institutions are not magically self-sustaining, and they “don’t protect against tyranny when powerful people start defying political norms.”

This particular norm is of paramount importance because the court’s institutional legitimacy depends on its perceived separation from the elected branches — a fragile concept in the best of times. By tying the latest appointment directly to the outcome of the election, Mr. McConnell and his allies took a torch to that idea — an outrageous gambit that, to nearly everyone’s shock, has paid off. But while Republicans may be celebrating now, the damage they have inflicted on the confirmation process, and on the court as an institution, may be irreversible.

The slope is both slippery and steep. If Republicans could justify an election-year blockade, what’s to stop Democrats in the future from doing the same? For that matter, why should the party controlling the Senate ever allow a president of the opposing party to choose a justice? Indeed, in the weeks before the election, Senate Republicans were threatening, with the encouragement of leading conservative thinkers, never to confirm anyone to fill the vacancy if Hillary Clinton won.

Can anything be done to repair the harm? One step — as obvious as it is unlikely — would be for Mr. Trump to renominate Mr. Garland. Conservatives will scoff, but they know he is as qualified for the job as anyone in the country. When Mr. Garland was floated as a possible choice for the Supreme Court in 2010, Orrin Hatch, the senior Republican senator from Utah, called him a “consensus nominee” and said there was “no question” that he would be confirmed with bipartisan support. That’s partly why Mr. Obama nominated him this time, and also why Mr. McConnell denied him a hearing — he knew he couldn’t prevent a Senate vote once Americans saw an eminently qualified and reasonable jurist testify on live TV.

At the very least, Mr. Trump could follow President Obama’s example and pick a centrist — someone who commands wide respect and operates within the bounds of mainstream legal thought. That would be an appropriate gesture from a man who lost the popular vote by more than 2.8 million votes and will enter office with the lowest approval ratings in recent history.

The shameful, infuriating actions of the Senate Republicans won’t be ignored in the history books. In a desperate effort to keep a conservative majority on the court, they rejected their own professed values of preserving American institutions. There’s little hope that they will come to their senses now, but they and Mr. Trump have the power, and the obligation, to fix the mess they created.