Hours later, the full Senate voted 49–51 against calling witnesses. “The motion is not agreed to,” Roberts said at 5:45 p.m. ET.

Read: The solemn absurdity of Trump’s impeachment trial

To be sure, Murkowski, who is routinely one of the handful of GOP senators who offer the slightest challenge to Majority Leader Mitch McConnell’s iron rule, lashed the impeachment articles from the Democratic House as “rushed and flawed.” Without mentioning her by name, Murkowski also scolded her colleague Elizabeth Warren, Democrat of Massachusetts, whose late-night question to the House managers yesterday demanded to know whether “the fact that the Chief Justice is presiding over an impeachment trial in which Republican senators have thus far refused to allow witnesses or evidence contribute[s] to the loss of legitimacy of the Chief Justice, the Supreme Court, and the Constitution.”

But even if her tears were crocodilian, it was the harshness of Murkowski’s criticism of the Senate itself that stood out. Her condemnation came at a moment when McConnell’s years-long legacy of hyper-partisanship, unremitting obstruction of Barack Obama, and unswerving loyalty to Donald Trump and his caucus’s raw political interests crystallized into a profound upending of the norms and procedures of the body he purports to revere.

After the House impeached Trump in December, McConnell took to the Senate floor to bemoan what he called an affront to history. “Historians will regard this as a great irony of this era,” he said, “that so many who professed such concern for our norms and traditions themselves proved willing to trample our constitutional order to get their way.”

Trampling order is a relative thing. McConnell himself has now ensured the only impeachment trial in Senate history that won’t have called witnesses. And until Murkowski and others forced him to change course, he had initially proposed not to automatically accept the documentary record compiled in the House as evidence in the Senate.

It is not necessary to romanticize the history of the Senate to acknowledge that something profound about it has changed. In the 1850s, it was the Senate that temporized America’s original sin of slavery in ways that all but guaranteed the Civil War. For the first half of the 20th century, the chamber was in the grip of southern racists who perpetuated vicious Jim Crow segregation.

But beginning with the civil-rights acts of the 1960s and continuing through Vietnam, Watergate, the CIA’s abuses of domestic and international intelligence, Iran-Contra, Bill Clinton’s impeachment, and the Senate Intelligence Committee’s unsparing investigation of the George W. Bush administration’s torture program, the Senate—in moments of great national peril—has generally risen to the occasion in at least some halting, lurching, imperfect, but still bipartisan way.