Campus police violated policy and used poor judgment when they used pepper spray against student demonstrators at a California university in November, according to a report into the incident.
The report, published on Wednesday, blamed administrators at the University of California-Davis administration for badly handling the campus protest.
"Our overriding conclusion can be stated briefly and explicitly. The pepper spraying incident that took place on November 18, 2011 should and could have been prevented," said the report by the university-appointed task force chaired by retired state Supreme Court Justice Cruz Reynoso.
Images of a police officer spraying the faces of seated nonviolent protesters became a rallying point for the Occupy Wall Street movement against economic inequality.
The 13-member task force said the decision to spray the protesters with the eye-stinging chemical had been "objectively unreasonable".
In a statement in response to the report, Linda Katehi, the University of California chancellor, said her university administrators would study the report's recommendations and develop a plan "that will ensure that students' safety and free speech rights are paramount".
Campus police officer John Pike and other officers involved in the pepper spray incident have said they needed to use the spray to break through a hostile crowd.
But the investigation said they found police office who were able to step over the seated protesters and walk through a throng of onlookers.
John Bakhit, an attorney for the campus police officers union, said the use of pepper spray was justified after protesters disobeyed orders to disperse and would not allow the officers to leave until several detained demonstrators were released.
"I believe all the officers exercised quite a bit of restraint under the circumstances," said Bakhit.
Fatima Sbeih, one of the pepper-sprayed students who is suing the university administrators and alleging police brutality, said she was pleased by the report's thoroughness and detail.
"The university was acting on assumption and fear rather than following policy and procedure," Sbeih said. "Students do have a right to protest, and the university needs to respect that".