The allegation, described as "pure Alice in Wonderland" by lawyers representing the staff - has added to the acrimony surrounding the dispute over contracts at Chippenham College in Wiltshire.
All five lecturers, who claim they signed new contracts rather than face the sack, attended some or all of last month's three-day hearing in Bristol to give evidence.
The following week, they received letters from the principal, Graham Baskerville, telling them to attend investigatory disciplinary interviews.
He said they went absent without leave as they had failed to submit an official request.
Solicitors acting for the lecturers' union NATFHE wrote back, saying: "There can be no doubt that the college were aware that the applicants would need to attend the hearing . . . Our clients and their union cannot resist the conclusion, with which we have considerable sympathy, that this is pure Alice in Wonderland."
The lawyers claimed Mr Baskerville had in March said the college would "insist" the lecturers attended the hearing without pay. They added that Mr Baskerville's actions were "wholly unjustified".
Then Mr Baskerville backed down saying that since a line manager's permission was obtained or implied in all cases, disciplinary action would not be pursued.
Meanwhile, the tribunal's ruling is expected shortly. In addition to the five claims for constructive dismissal, two lecturers who refused new contracts and no longer work at Chippenham are claiming unfair dismissal.
The appeal is seen as a pivotal case for FE lecturers resisting moves to scrap pre-incorporation contracts in favour of shorter holidays and longer working hours.
Chippenham claims it was obliged to introduce new working practices to improve productivity and save money.
Mr Baskerville was unavailable for comment.