French police banned a planned demonstration against labor reform on Wednesday, bringing to a head a stand-off between the government and trade unions over how to allow legitimate protest without triggering the violence that has marred past marches.

Unions have been organizing protests for months against a draft law that will overhaul labor rules to make hiring and firing easier. One such protest is planned for Thursday.

This week the government said it would only allow a static rally in Paris in an attempt to contain any violence, but unions have said a ban on marching would be unacceptable, and that they would maintain plans to walk through the streets of the French capital.