Loyalists are mounting a legal challenge against a decision by Northern Ireland's Parades Commission to place restrictions on a contentious 12 July march in north Belfast on Thursday.
The Commission has ordered that the parade through Ardoyne finish several hours earlier than usual this year.
The North and West Belfast Parades Forum is seeking a judicial review of the ruling.
A spokesman for the group, Winston Irvine, says the forum also wants to overturn a decision to allow republican protesters to hold a counter-demonstration in Ardoyne shortly after Orangemen are due to pass the interface.
About 100 Orangemen protested in north Belfast against the restrictions.
Sinn Féin is also unhappy with the decision, and has called for the return leg of the parade to be rerouted.
Earlier, Parades Commission Chairman Peter Osborne appealed for calm ahead of Orange Order marches marking 12 July.
In a statement, Mr Osborne said the number of sensitive parades was decreasing.
He said there had been a real improvement in the atmosphere surrounding such marches and that a peaceful summer would encourage progress.
Last night up to 250 Orange Order members protested outside Hillsborough Castle, after the Commission placed restrictions on a parade due to take place in Co Antrim on Thursday.
