A legal challenge to the Parades Commission's decision to allow the Orange Order to march on the mainly-nationalist Garvaghy Road in Portadown is under way at the High Court in Belfast, where a large crowd has gathered outside.
The commission announced that the parade can proceed on Sunday, for the first time in almost 30 years, with restrictions in place.
Rather than start at 13:00 BST on Sunday as intended, the commission has said the march can depart no later than 08:00 and with 35 participants rather than the 60 the Orange Order requested. No bands or supporters are allowed.
The decision is facing the legal challenge from the Garvaghy Road Residents' Coalition, which opposes the march.
A lawyer for the residents told the court it was unclear whether the Police Service of Northern Ireland's (PSNI) assessment referred to in the determination, was the "entirety" of what the police told the Parades Commission.
Their legal team has asked for the full PSNI assessment as well as past assessments in order to see whether there had been any changes.
Counsel for the residents said there had been a "significant change" in the Parades Commission's approach.
Before adjourning the proceedings, Judge Patricia Smyth told the parties involved she would like to hear from them on a way forward in the short amount of time that was available.
Following Friday's determination, the priest said he emailed the commission to express his concerns and stated he "doesn't know how they came to" their conclusion, which is now "out of their hands".
Fr Clarke said he has "unhappy recollections" of the Drumcree dispute during the 1990s and "wouldn't like to see" a return to those days.
Parishioners at St Patrick's Church on William Street are also likely to be affected ahead of the 10:00 service, according to the priest.
He added "tensions are high" in the community, and said he will be addressing the situation during Sunday's service.
In a statement issued on Saturday, the Portadown District Orange Order branch said while they were "not happy" with further restrictions to their parade, they would "comply fully with the law and determination".
"We now ask our community to do likewise. We would appeal to everyone to conduct themselves responsibly and peacefully and not to do anything that could increase tensions within the community," District Master Nigel Dawson said.
Dawson added the lodge had followed the commissions determinations for 28 years and "all we ask now is that same respect" is shown by those affected by this decision.
The five-person commission, led by Prof Evelyn Collins, held face-to-face talks with the Orange Order earlier this week, and held a separate meeting with the residents' coalition.
Senior police officers were also consulted about the planned parade.
Within the 31-paragraph determination by the Parades Commission, details were revealed of conversations held with the PSNI.
The document stated: "The police made both written and oral submissions, indicating that they, at the time of making them, had no information indicating that the parade would result in disorder or violence."
The Police Service of Northern Ireland (PSNI) said it had activated "mutual aid arrangements to support contingency planning for a policing operation" in Portadown on Sunday.
It is understood about 200 officers are coming from Scotland.
The Parades Commission has been in the political spotlight since its previous Drumcree determination was quashed in the High Court in August.
A review of the commission has since been ordered by the Northern Ireland Office.
The Drumcree parade dispute began in the mid-1990s and it almost derailed the peace process at the time.
Violence related to the dispute resulted in riots, roadblocks and murders.
When the Orange Order was prevented by police from walking down the route in July 1995 there was a tense stand-off. It was the same for the next three years.
The Parades Commission began operating in 1998 to regulate parades and try to defuse tension around marches.
Its decision not to allow a march down the Garvaghy Road that summer has been challenged by the order over the past three decades.
