The Parades Commission has banned the return leg of an Orange Parade on July 12 which goes past the Ardoyne shops in North Belfast.
The Orange Order has branded the decision made by the PC as "preposterous," adding that the decision "underlines the increasing perception that its determinations are dictated by the threat of physical force opposition to our parades."
Now Unionist politicians have walked out of critical party talks ahead of the Twelfth fortnight, leaving the Assembly in limbo.
A joint statement released by the DUP, UUP, PUP, TUV and UPRG said: "The message the Parades Commission has sent out is simple.
"It has shown that the Commission members place no value on a relationship with unionism and have treated our advice with contempt.
"It has turned its face away from the evidence including from the PSNI. It is regrettable, but so be it."
They added: "As a consequence we, as leaders of the unionist community, see no value in continuing contact with a Parades Commission that does not listen and is immune to reason."
East Belfast Alliance MP Naomi Long tweeted her condemnation at the combined unionist decision to walk out of the talks:
Some of the worst rioting Northern Ireland has seen in recent years broke out last summer after the PC banned the parade from taking the same return route.
Since then, loyalists have protested at Twaddell Avenue, directly facing the Ardoyne shops, in opposition to the PC's decision.
A statement released by the parades governing body read: "The issue of parading along the Crumlin Road has profound implications for communities coming out of conflict and requires resources and structures commensurate to the task.
"It is the Commission's view that while there have been efforts to address these issues they have been piecemeal and under resourced.
"The Commission recognises that this parade brings to the fore tensions beyond the actual procession, the arterial route that it processes and its six minute duration, but that these are outweighed by the symbolic and historic significance of this parade route at an interface area.
"The Commission has received evidence that fractured community relations arise from past events which have occurred on this contested stretch of the Crumlin Road and which contribute to the sensitivity of the parade route."
The Orange Order said of the decision: "Such reckless action comes despite the prolonged and genuine efforts by the County Grand Orange Lodge of Belfast, and primarily the Ligoniel lodges, to defuse tensions concerning Loyal Order parades in this part of the city over the past 12 months, including face-to-face discussions with nationalist residents.
"There will quite rightly be indignation across the entire Unionist community at the latest restriction on our legitimate cultural expression and traditions and therefore the Orange Institution will be meeting with our political leaders at the earliest opportunity to discuss further the ramifications of this decision."
In the statement, the Orange Order spokesperson appealed for calm and restraint from any violence.
They said: "Any violence will only undermine our cause. We would reiterate that anyone wishing to protest against this outrageous decision must do so in a peaceful manner. Only then can civil and religious liberty prevail."