Last weekend, a pre-St. Patrick's Day rite that drew more than 4,000 people degenerated into violent confrontations with police officers, who donned riot helmets and used pepper spray to break up crowds that lobbed beer bottles, snowballs and fireworks, reports the New York Times . The Amherst, Mass., police said they arrested 55 people and issued additional summonses, with charges ranging from disorderly conduct to assaulting a police officer.

"This is the largest I've ever seen it, and I've been a police officer in town for 30 years," said Amherst PD Police Chief Scott P. Livingstone.

The melee angered university administrators, led to complaints on campus about the use of force by the police, and confounded residents, who wondered how the partying could be controlled. On Thursday, the university announced that it had retained Ed Davis, a former Boston police commissioner who led the department during last year's bombings at the Boston Marathon, to review the way the university and the town handled Saturday's disturbance and previous ones.

"You're never going to do away with incidents of this kind on college campuses or cities when large numbers of people want to celebrate," said Robert L. Caret, the president of the five-campus University of Massachusetts System. "What you want to think about is how you mitigate this from becoming an unlawful, dangerous situation."