A group representing fast food outlets has started a constitutional challenge to the way pay and conditions are set for workers in the catering sector.
If the High Court challenge succeeds it could lead to lower wages and conditions for hundreds of thousands of workers in a number of sectors.
The Quick Service Food Alliance and John Grace Fried Chicken of Cork are claiming that the Joint Labour Committee (JLC) system of setting wages and conditions for catering workers is arbitrary and a disproportionate breach of the property rights of employers.
Opening the case Senior Counsel Brian Murray said many fast food outlets had been unaware until 2008 that the sector was governed by a JLC and employment regulation order since 1978.
Mr Murray said it was arbitrary that the employment regulation order applied to fast food outlets with seats but not to those without seating while the catering workers in both establishments were doing the same work.
He also pointed out that there was inconsistency as outlets in Dublin and Dun Laoghaire only had to pay overtime at time and a third while those in the rest of Ireland had to pay double time on Sundays. He also pointed out that breaching an employment regulation order is a criminal offence.
The Quick Service Food Alliance represents a range of different fast outlets, including Subway, Abrakebabra, Bagel Factory, Burger King, Eddie Rockets, Supermacs and Hillbillies, as well as a number of sandwich bars and Italian takeaways.
The State, which is defending the JLCs, has not yet opened its case.