Tension had been building at Princeton University as pro-Palestinian demonstrators occupied a white-columned, Greek Revival-style building at the center of campus and the police moved in. An angry crowd had surrounded a bus where two demonstrators were being held after officers led them out of the building.

“It was a tense time as there were hundreds of protesters that were attempting to interfere with lawful arrests,” reads a police report from that day, April 29, 2024.

David Piegaro, then a Princeton junior, was there filming with his phone. Mr. Piegaro says he was not one of the protesters, and he opposes much of their language and tactics. He described himself as a pro-Israel “citizen journalist” who was concerned by what he saw as the university’s insufficient response and wanted to bear witness by recording.

By nightfall, he was one of more than a dozen students charged with wrongdoing at the elite New Jersey school. He joined the roughly 3,100 people arrested or detained last spring on campuses across the county amid a wave of student activism over the war in Gaza.

Trespassing charges are pending against the pro-Palestinian demonstrators arrested at Princeton that day. But Mr. Piegaro, who was charged with assault, is so far the only person to have stood trial. A municipal court judge who presided over the two-day proceeding in February is expected to announce a verdict on Tuesday.

The Trump administration has made a dramatic show of punishing or trying to punish college-age protesters who have spoken out against Israel’s military response in Gaza, where the death toll has surpassed 50,000 people.

The administration has either detained or threatened to deport at least nine international students or faculty members, including a Tufts University graduate student who had co-written an opinion piece in the student newspaper criticizing the university’s response to pro-Palestinian demands. She was taken into custody last week.

But the arrest and trial of Mr. Piegaro, who was born and raised in New Jersey, underscore the complexity of the issues facing university administrators and the police as they strive to balance respect for free expression with questions about what constitutes hate speech.

Mr. Piegaro, 27, is older than most undergraduate students. He began studying at Princeton after serving for several years in the U.S. Army, where he worked as an intelligence analyst with a top-secret security clearance.

He is Jewish and said he was troubled by the deadly attack on Israel by the terror group Hamas, which killed about 1,200 people, and the tactics of the growing pro-Palestinian movement on campus.

He said he was not, however, involved in the protests or counterprotests. And one of the charges brought against him — aggravated assault — was far more serious than the trespassing citations filed against 13 other Princeton students charged that day.

As Mr. Piegaro’s case has moved through the criminal justice system, three of the charges he initially faced, including aggravated assault, were dropped or reduced. He and his lawyer, Gerald Krovatin, said he twice refused offers to plead guilty to a lesser charge, convinced of his innocence and unwilling to voluntarily mar his record with a conviction of any kind.

He went to trial on a lower-level assault charge, equivalent to a misdemeanor, that carries a potential penalty of six months in jail and a $1,000 fine.

“I really believe I’m the victim,” Mr. Piegaro said in an interview. “I really don’t think I did anything.”

The run-in that led to his arrest involved the head of the school’s campus security department, Kenneth Strother Jr.

Mr. Piegaro, upset that more than a dozen of the protesters had been released with citations, had begun recording two of their faculty advisers, who were speaking with Mr. Strother and walking toward Whig Hall, a building adjacent to Clio Hall, the one that had been occupied.

Mr. Strother barred Mr. Piegaro from trying to follow them in, and Mr. Piegaro can be heard on the video he recorded asking Mr. Strother, who was not in uniform or wearing a badge, his name and position.

“Don’t touch me,” Mr. Piegaro says before the video abruptly ends. Seconds later, he says, he was tumbling down the front steps of the building.

What happened in between is the crux of the dispute.

According to Mr. Strother, whose account appeared in the police report, Mr. Piegaro “pushed himself” into Mr. Strother, who “grabbed Mr. Piegaro by his arm and told him he was under arrest.” Mr. Strother said that he lost hold of Mr. Piegaro, who was resisting arrest, causing Mr. Piegaro to fall down the stairs.

Mr. Piegaro says he was the one who was assaulted.

Sarah Kwartler, a graduate student who had gone on two dates with Mr. Piegaro several years ago and recognized him, testified that she stopped to watch part of what unfolded.

She said she saw Mr. Strother holding Mr. Piegaro “like an open pair of scissors,” losing his grip and dropping him, according to a summary of the testimony submitted to the judge. Mr. Piegaro then rolled to the bottom of the stairs, Ms. Kwartler said, where he was handcuffed and arrested.

Complaining of soreness, Mr. Piegaro was taken to a hospital and evaluated for broken ribs and a concussion. Mr. Strother, who did not reply to requests for comment, was uninjured, according to the police report.

Mr. Krovatin, Mr. Piegaro’s lawyer, has argued that the decision to initially charge his client with aggravated assault, in addition to several other crimes, smacks of disparate treatment when compared with the lower-level trespassing charges leveled against the protesters.

“The fact remains that the only student charged with three indictable offenses on that day was a Jewish U.S. Army veteran,” Mr. Krovatin said, adding, “I don’t get why Princeton hasn’t pulled back on this.”

A spokeswoman for Princeton, Jennifer Morrill, said that the university deferred to the judgment of the municipal prosecutor and the municipal judge. She drew a distinction between Mr. Piegaro’s assault case and the trespassing charges filed against the protesters.

With regard to the trespassing charges, she said, “The university is not a party to — and has not intervened in — those court proceedings, though the university has consistently said that it supports an outcome that would minimize the impact of the arrest on these individuals.”

She added, “The university has no comment on the separate charges filed against an individual in connection with his interaction with a police officer.”

Two of the pro-Palestinian demonstrators arrested at Princeton last April declined to comment. Princeton’s municipal prosecutor, Christopher Koutsouris, did not return calls or emails.

Mr. Piegaro said that after he was arrested, he was barred from student housing and from campus for about two weeks. He spent a few days living with Rabbi Eitan Webb, a Jewish chaplain and director of Princeton University’s Chabad House.

Rabbi Webb, in an interview, recalled a “pressure-cooker effect” on campus last spring.

“In that environment, speaking specifically to the events of that day, when you have a whole host of public safety officers, administrators — I think doing their best — it’s not surprising that mistakes would get made,” Rabbi Webb, who attended Mr. Piegaro’s trial, said.

He said he believed that the testimony showed that Mr. Piegaro was “not guilty.”

Breh Franky, who works in Princeton’s public safety department, testified that Mr. Piegaro had made contact with Mr. Strother as the student “charged the door,” according to the summary of the testimony.

But Zia Mian, one of the two faculty advisers who was speaking with Mr. Strother during the confrontation, testified, “This was not an attempt to attack the chief.”

Unlike many universities, Princeton quickly quashed efforts last April by pro-Palestinian demonstrators to erect tents on campus. At least two people were charged after they refused to take down tents. The takeover of Clio Hall on the night Mr. Piegaro was arrested lasted only about two hours after students were given a deadline to exit and told that they would face arrest.

The school has also managed to avoid much of the turmoil that has engulfed the presidents of several other prominent universities, including some who were summoned to testify before Congress about their schools’ responses to antisemitism on campus.

Ms. Morrill said that Princeton’s “expansive commitment to free speech — which includes peaceful dissent, protest and demonstrations — remains unwavering,” while noting the school’s rules governing the time, place and manner of such demonstrations. And the campus continues to bustle with signs of vigorous academic debate.

On Wednesday afternoon, the school is holding a forum on academic freedom and “whether, when, and how universities should take institutional stances on social and political issues.” Later this week, a conference is set to take place on the history, theory and politics of the “anti-Zionist idea.”

Keith A. Whittington, a longtime Princeton professor who is teaching this year at Yale Law School, is one of three academics participating in Wednesday’s forum. Professor Whittington, a free speech scholar, was on Princeton’s campus the day the pro-Palestinian demonstrators occupied Clio Hall but did not witness Mr. Piegaro’s arrest.

“It just sort of indicates how fraught things are on campuses, and how volatile these situations are,” Professor Whittington said.

In the moment, he said, facts can be difficult to parse.

“That’s why you have trials,” he said.