They doodled. They nodded off. They kicked their feet up. They giggled. They tapped their fingers impatiently. They passed notes.

This wasn’t the conduct of high school teenagers, but rather U.S. senators during an impeachment trial intended to hold accountable former president Donald Trump, who was impeached by the House on a charge of inciting his supporters to storm the U.S. Capitol on Jan. 6.

On the Democratic side Friday, several senators laughed or shook their heads in disbelief as Trump’s attorneys showed footage of them and other Democrats urging their supporters to “fight” for one cause or another, attempting to draw a comparison between that and Trump’s rhetoric before the Jan. 6 riot.

And on the Republican side, many senators throughout the week have treated the proceedings with barely disguised contempt, viewing the impeachment trial as an unconstitutional attack on a former president who is not culpable in the violence.

During the question-and-answer portion of the trial Friday afternoon, Sens. Tim Scott (R-S.C.) and Bill Hagerty (R-Tenn.) asked the defense whether it wasn’t just a “political show trial.”

The dismissive behavior of some senators is a departure even from Trump’s first impeachment trial a year ago, when he was acquitted by the Republican-controlled Senate on charges that he improperly pressured Ukraine to try to damage then-presidential candidate Joe Biden. Many GOP Republicans sat and listened to the proceedings even if the outcome, like now, also appeared to be predetermined.

“I think there is a general air of disrespect, from what’s been reported, and in certain cases performative disrespect,” said Frank O. Bowman III, a University of Missouri law professor and expert on impeachment. “It disrespects not just the process, but the institution.”

Earlier in the week, Scott called the trial a “waste of time” and was seen studying a map of Asia. As the Democratic House managers presented their evidence, Sen. Rand Paul (R-Ky.) drew a sketch of the U.S. Capitol, Sen. Josh Hawley (R-Mo.) propped his feet up on the seat back in front of him and Sen. Mike Braun (R-Ind.) read a newspaper.

When the House managers showed gruesome images and played previously unseen security footage that depicted a furious mob intent on desecrating the same building where the senators sat, some Republicans were visibly gripped with emotion. Most, however, are poised to vote against Trump’s conviction, arguing that he does not bear responsibility for what occurred.

The heaviness of the previous days lifted Friday when the Trump defense began its presentation, airing a montage of videos showing Democrats urging their supporters to “fight.” Several Democrats did little to hide their feelings.

Sen. Jon Tester (Mont.) could be heard laughing when he was featured on screen. Sen. Kirsten Gillibrand (N.Y.) appeared to giggle when she was shown. Sen. Richard J. Durbin (Ill.) was looking at the ceiling with his hands as if in prayer, tapping his fingers together impatiently. Other Democrats whispered and nudged one another.

When former president Bill Clinton was impeached in 1999, the GOP Senate majority issued a “decorum guidance” ahead of the trial, directing senators not to chat among themselves, to turn off their cellphones and to read only materials pertaining to the trial. The guidelines were written “to lend the greatest dignity to these proceedings, reflect the civility of the Senate and illustrate our respect for the Chief Justice and those who have the responsibility of presenting the impeachment case and defense,” The Washington Post quoted from the document at the time.

Senators gathered in a private room to deliberate and debate the evidence, and the Clinton White House didn’t know whether Democrats would decide to remove him, Bowman said.

This week, Sen. Roy Blunt (R-Mo.) referred to Trump’s lawyers as “our side.” When the Democratic managers rested their case on Thursday, Sens. Lindsey O. Graham (R-S.C.), Ted Cruz (R-Tex.) and Mike Lee (R-Utah) openly walked into a room with Trump’s defense team for a private meeting to discuss strategy.

“If this were a real trial, the jurors and the defense lawyers would all be in contempt of court by meeting,” said Stephen Gillers, a Constitution and ethics expert at the New York University School of Law. “Also, jurors and the accused would both be in contempt if they conferred. But the Senate proceeding has as much resemblance to a real trial as the heart on a Valentine’s Day card has to a real one. The judge is a juror, some jurors announced their verdict before the trail, and there are no rules of evidence or witnesses. So what’s one more transgression?”

Then-Senate Majority Leader Mitch McConnell (R-Ky.) set a precedent ahead of Trump’s first impeachment trial for conferring with the defense, telling reporters in 2019: “Exactly how we go forward, I’m going to coordinate with the president’s lawyers. The case is so darn weak coming over from the House. We all know how it’s going to end.”

Bowman said there have always been some communications between senators or their staff with the side they favor, but never as brazenly.

“To baldly walk in when everyone can see you and declare your allegiance in a proceeding in which you’re supposed to be deciding impartially is disrespectful to the process,” he said.

“You get why they are behaving the way they are: They need to behave as if this immensely serious, incredibly solemn, constitutionally consequential event is a joke,” he added. “If you can poke fun at the whole thing, it’s easier to justify your abdication of responsibility.”

Correction: An earlier version of this story misidentified one of the senators who asked about a “political show trial.” Sen. Tim Scott (R-S.C.) asked the question, and the story has been corrected.

Tom Hamburger and Karoun Demirjian contributed to this report.