The meeting was illegally broken up, according to Bartley, by a building manager who refused to identify himself, interrupted the meeting, and demanded that the participants leave. The manager then called the police.

Because the building manager is a Harvard employee, Bartley said the union brought its grievance to the Office of Employee and Labor Relations.

“Both under federal labor law and in the contract that we have the right, especially when we’ve given proper notice, to meet with workers at the worksite,” he said.

But Touborg said that miscommunication between the union and university representatives was the real issue.

“In this case, [notification procedures] were not observed, at least in the eyes of the university representative on site, but in the eyes of the union they were observed,” she said. “I think it’s a disagreement about whether they had observed or not observed the standard operation instructions for gaining access to the building.”

PSLM members involved in the protest did not return calls for comment.

—Staff writer Stephen M. Marks can be reached at marks@fas.harvard.edu.