May 2 (Reuters) - At Columbia University, tensions

between the administration and students protesting over Israel's

war in Gaza have reached the point that scores of New York City

police marched onto campus to clear an encampment and arrest

demonstrators who had commandeered a classroom building.

It was the second time in as many weeks that the

administration has called on police to control the protests.

Students have been suspended, and threatened with expulsion.

Police are now stationed around-the-clock on campus.

Nearly three thousand miles away at the University of

California, Berkeley, the scene has been far different. Student

demonstrations have so far taken place without arrests or

disruption of campus operations.

The contrast in how protests have played out at the two

prestigious institutions - both with long histories of student

activism - illustrates the range of factors at play in how

school administrations, students and the police navigate what

can quickly turn into a full-blown crisis.

South of Berkeley at UCLA, part of the same university

system, police on Thursday morning flattened a pro-Palestinian

camp, a day after it was attacked by pro-Israel counter

protesters. Authorities at the Los Angeles school had declared

the encampment an unlawful assembly.

Similar crackdowns have occurred at colleges across the

country, from Arizona State to Virginia Tech and Ohio State to

Yale. Police have arrested around 2,000 campus protesters to

date.

Still, some universities - including Berkeley, Northwestern

and Brown - have managed to avoid confrontations between the

police and students.

Education experts say these cases offer lessons in keeping

tensions from boiling over, a key one being a university's

experience with balancing student activism against pressure from

donors, interest groups and politicians.

Berkeley Chancellor Carol Christ has allowed students to

maintain a protest space on campus since they began erecting

tents April 22 on the steps of Sproul Hall, where Martin Luther

King gave a 1967 civil rights speech. Dan Mogulof, a spokesman

for the university, said that remained the case Thursday,

despite a scuffle Wednesday evening between the co-founder of a

Zionist activist group and a pro-Palestinian protester. It was

the first violence after days of peaceful assembly.

"We are urging everyone to avoid engaging in pointless

provocation and physical conflict," Mogulof said, adding that

Christ was in talks with encampment leaders after the Wednesday

incident led to three minor injuries. He said the school would

respond to violence in line with University of California

policy.

That guidance tells administrators to avoid police

involvement unless it's absolutely necessary and the physical

safety of students, faculty and staff is threatened. That policy

is rare, with most universities having some kind of regulation

that prohibits permanent encampments or outlaws overnight

student activities on campus.

The University of California system has seen in the past

where police involvement can lead.

In a 2011 Berkeley protest during the Occupy movement

against economic inequalities, campus police clubbed and jabbed

students with batons. Then-Chancellor Robert J. Birgeneau later

apologized, and the UC system shifted to the policy of restraint

Berkeley spokesman Mogulof described.

Amid current protests, administrators across the country are

seeking to ease tensions with talk. In Illinois, Northwestern

University reached a deal with protesters to remove tents and

sound systems in return for a new advisory committee on

investments, a key policy for students who object to their

school's financial ties to companies that back Israel's

government.

Protesters at Brown University in Rhode Island also agreed

to take down their encampment in return for a vote by the

college's corporation on whether to divest funds from companies

tied to Israel's military attacks on Gaza.

Still, some deals have failed to resolve tensions. While

Portland State University in Oregon agreed to pause donations

from Boeing ( BA ), a company that makes attack helicopters used in

Gaza, students there have nonetheless occupied the library,

scrawling messages like "END GENOCIDE NOW" on windows.

Other factors at play as institutions navigate balancing

free speech and campus security include how students react to

daily developments in the Middle East as well as those at other

campuses in the United States.

Columbia has often proven to be a beacon for protest

movements at other universities. President Minouche Shafik has

said the campus has become "intolerable," citing factors ranging

from antisemitic language to loud protests going into the night.

"One group's rights to express their views cannot come at

the expense of another group's right to speak, teach, and

learn," Shafik said in a Monday statement.

Adversaries of pro-Palestinian protesters accuse them of

antisemitism, a claim Columbia student protesters and their

faculty advocates strongly deny.

Free-speech attorney Zach Greenberg said no matter how

hateful or offensive the speech on campuses, it was not a

justification for police crackdowns.

"It's always better to counter the speech you dislike with

more speech," said Greenberg, a program leader at the college

campus rights advocacy group FIRE.