Princeton University president Christopher Eisgruber said in an op-ed published in the school paper Thursday that while the university embraces free expression, there are limits regarding the time and places where protests occur. 

"Princeton’s time, place, and manner regulations include a clear and explicit prohibition upon encampments. They provide that 'camping in vehicles, tents, or other structures is not permitted on campus. Sleeping in outdoor space of any kind is prohibited,'" he wrote.

He said that encampments obstruct others from moving freely on campus, create health and safety risks, there’s no way to bar outsiders from joining in and, as proven by recent events on other campuses, “encampments are also prone to become sites of confrontation.” 

"Dialogue, debate, and deliberation depend upon maintaining a campus that is free from intimidation, obstruction, risks to physical safety, or other impediments to the University’s scholarship, research, and teaching missions," he said.

Police said 108 people were arrested in protests around Emerson College Wednesday night. 

Boston police said that no protesters were injured, and those arrested will be arraigned in Boston Municipal Court. Four officers suffered non-life-threatening injuries — three minor and one “more serious.”

The nation's colleges are set for another day of pro-Palestinian protest and disruption with sit-ins, rallies and walkouts planned across the country.

Activists at Georgetown, Penn State and Syracuse universities are all due to hold rallies or protests at 10.30 a.m. ET, while more are planned throughout the day at Fordham, Purdue, Indiana, Brown, Stanford, and many more.

Events are expected to continue at least until a teach-in at the University of Virginia at 7.30 p.m.

Events are also planned for tomorrow, in a sign that the protest movement is not slowing down.

The pro-Palestinian protest movement that has swept across the country's universities this week shows no sign of stopping, with ongoing camps at least campuses, according to NBC News' research.

Since the encampment began at New York's Columbia University on April 17, there are now similar camps from Emerson College in Boston to the University of Southern California in Los Angeles.

Other major schools with encampments include Yale in Connecticut; the University of California, Berkeley, and the University of Texas, Ausatin.

There is also an encampment at the University of Alberta in Edmonton, Canada.

Columbia University's president, Minouche Shafik, received a strong vote of confidence from the institution's board of trustees last night, as pro-Palestinian protests continue on campus and at other colleges across the country.

The statement came after House Speaker Mike Johnson called on her to resign yesterday.

"The Columbia University Board of Trustees strongly supports President Shafik as she steers the university through this extraordinarily challenging time," the board said in a statement.

The board said Shafik, who took up the post on July 1, 2023, had promised to "take a thoughtful approach to resolving conflict, balancing the disparate voices that make up a vibrant campus like Columbia’s, while taking a firm stance against hatred, harassment and discrimination."

"That’s exactly what she’s doing now," the statement said, adding that the board was "urgently working with her to resolve the situation on campus."

On Monday Shafik said she was "saddened" by the situation on campus and called on protest leaders to compromise and sit down for talks.

Israeli Prime Minister Benjamin Netanyahu called on Jews and non-Jews to oppose pro-Palestinian protests on campuses across the United States, comparing them to the antisemitism seen in Nazi Germany in the 1930s.

"What's happening in America's college campuses is horrific. Antisemitic mobs have taken over leading universities. They call for the annihilation of Israel, they attack Jewish students, they attack Jewish faculties," he said in a statement posted to X on Wednesday.

"This is reminiscent of what happened in German universities in the 1930s. It's unconscionable — it has to be stopped, it has to be condemned and condemned unequivocally," he said.

The protest at the University of Southern California, where at least 93 people were arrested according to police, has ended for the night.

The campus is closed and only students and staff with proper ID will be admitted, the school said.

"The protest on the UPC [University Park Campus] has ended. However, the campus remains closed until further notice. Students, faculty, staff, and people with business on campus may enter with proper identification," the USC Department of Public Safety said in a statement.

Earlier, LAPD said patrols would continue on campus through tomorrow.

There was a large police presence at a protest near Emerson College in Boston in the early hours of this morning, as seen in these images shared by Working Mass, the labor outlet the of the Democratic Socialists of America in Massachusetts.

The sister of one of four people killed by the National Guard at Kent State University in Ohio in a notorious incident during the Vietnam War today condemned calls by some Republicans for the military to be called in to quell campus protests.

House Speaker Mike Johnson, R-Louisiana, was asked today at Columbia University about calls for the military to be used. “If this is not contained quickly, and if these threats and intimidation are not stopped, there is an appropriate time for the National Guard," he said.

No governor has yet called for the National Guard for the student protests.

Laurel Krause, the sister of 19-year-old Allison Krause, who was fatally shot at Kent State on May 4, 1970, called on universities to support the rights of students to protest.

“In 1970 failures of Kent State University leadership enabled the massacre which left ‘Four Dead in Ohio,’” Krause said in a statement, referring to lyrics in the famous Neil Young song “Ohio.”