A group representing fast food outlets has begun a constitutional challenge to the way pay and conditions are set for workers in the catering sector.
If the 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 say that the Joint Labour Committee system of setting wages and conditions for catering workers is arbitrary.
They also say it is 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 Joint Labour Committee and Employment Regulation Order since 1978.
He 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.
The fast food outlets in the Quick Service Food Alliance include Subway, Abrakebabra, Bagel Factory, Burger King, Eddie Rockets, Supermacs, Hillbillies, as well as a number of sandwich bars and Italian takeaways.
The State, which is defending the Joint Labour Committee system, has not yet opened its case.