The dispute centres on pay, working conditions and union recognition.
Staff at the school have raised a number of issues about pay and conditions.
The decision follows a case taken by the Irish Human Rights and Equality Commission (IHREC).
A backlog in applications also means the current processing time for standard work permit applications is 13 weeks.
The case was brought before the Workplace Relations Commission.
The hotel which employed the woman was ordered to pay her compensation by the Workplace Relations Commission.
Although the retail worker successfully sued the supermarket, the Labour Court found she contributed to her dismissal.
Clontarf Hospital lost 41 staff between 2016 and 2017.