The Association of University Teachers has threatened Queen's University Belfast with a judicial review as the bitter row over lecturer redundancies deepens.
The warning came as AUT leaders met Queen's vice-chancellor George Bain at the TUC conference in Blackpool.
AUT general secretary David Triesman and his assistant, Brian Everett, demanded a series of assurances including a pledge there will be no compulsory redundancies.
But it is understood a number of staff have already volunteered to take redundancy, and the AUT will not oppose them. A meeting has also been arranged between union representatives, pro vice-chancellor Malcolm Andrew and senior Queen's management for October 1.
Assistant general secretary Mr Everett said: "This is the biggest dispute we have with any university in the country, although we have not yet gone into a formal dispute situation.
"We will be telling Mr Bain that, unless he can reassure us on a number of matters, particularly on how staff will be treated, we will go to judicial review. We have concerns about how individuals are being treated and we want to pay attention to how certain subjects are under threat."
AUT leaders also urged Professor Bain, who was at the TUC conference for a seminar on the minimum wage, to begin consultation with politicians and with the Department of Education on its revamp plans. "We are concerned about all departments under threat, but we have to ask what the economic implications are of closing geology when oil and gas are about to be discovered off the west coast."
Mr Everett said "our bottom line, of course, is that there must be no compulsory redundancies".
Under the Pounds 25 million restructuring, four departments - geology, domestic studies, Italian and operational research - are targeted for closure and 107 academics who have been branded "research inactive" and would be replaced with 110 "high-calibre" people in selected areas.