A judge who heavily criticised a watchdog probe into alleged police collusion in a notorious loyalist atrocity has been asked to withdraw from the case amid claims he held a subconscious bias.
Mr Justice McCloskey delivered a damning judgment against Northern Ireland's Police Ombudsman Dr Michael Maguire last month, ruling that he had exceeded his statutory powers by declaring officers guilty of colluding in the Ulster Volunteer Force shootings in Loughinisland, Co Down in 1994.
The Ombudsman and relatives of the six Catholic men shot dead have jointly applied for the judge to recuse himself because, as a barrister, he once represented one of the two retired police officers who mounted the judicial review challenge against Dr Maguire's findings.
The judge, who has insisted he has no memory of representing the officer in the 2002 case related to a separate Police Ombudsman's probe into the 1998 Omagh bomb, said he would take time to consider the application and announce his decision next week.
In a landmark 2016 report, Dr Maguire found that Royal Ulster Constabulary (RUC) officers colluded in the UVF gun attack in the village of Loughinisland.
Two loyalist gunmen burst into the Heights Bar and opened fire on locals watching the Republic of Ireland play Italy in USA '94.
Two retired officers took judicial review proceedings against the Ombudsman's findings and judge McCloskey found in their favour in December.
He has however yet to complete his judgment in respect of whether the Ombudsman's report should be formally quashed. The joint application for recusal has been submitted ahead of him issuing that decision, which had been expected on Friday.
The issues were aired in court during over two hours of legal exchanges on Friday.
Fiona Doherty QC, representing the families, said the application was being made with regret and only after careful consideration.
She made clear she was not questioning the professional integrity of the judge but said his role in the historic case could lead to public unease about him presiding in the current proceedings.
"At the very least there is a doubt, " she said. "Where there is a doubt it should be resolved in favour of recusal."
Barra McGrory QC, representing the Ombudsman, faced intense questioning from the judge over the merit of the application.
Mr McGrory, Northern Ireland's former Director of Public Prosecutions, said a reasoned independent observer might find it "difficult to accept" the judge's assertion that he did not recall his involvement in a case related to such a high-profile atrocity as Omagh.
"The apprehension of bias, either direct or subconsciously, is all that needs to be established," he said.
The judge highlighted that he was bound by a solemn oath to be rigorously impartial and he challenged lawyers to point him toward the "slightest whiff of unconscious bias" in his judgment.
He suggested to Mr McGrory that a DPP would be bound by a similar duty to be impartial in all cases, regardless of who they had represented previously in their legal career.
The judge also drew the court's attention to a judgment he had delivered in 2010 where he was highly critical about the conduct of police officers.
David McMillen QC, representing the retired officers, said the application was "absolutely without foundation".
He said the judiciary had a proud record of independence in Northern Ireland, demonstrated during the violent years of the Troubles.
"A fair-minded observer wouldn't even think for one moment there's a real possibility of bias in this," he said.
At the close of oral submissions, Justice McCloskey told the court he was faced with a "complex and challenging" decision.
"The effect is that it's not possible for the court to indicate its decision now," he said. "I regret that greatly because the families are going to be delayed once again."
The judge said he would rule on the matter on January 26. He indicated that, if he decided to retain the case, he would then deliver his judgment on the fate of the Ombudsman's report.
The men who died at Loughinsland were Adrian Rogan, 34, Malcolm Jenkinson, 53, Barney Green, 87, Daniel McCreanor, 59, Patrick O'Hare, 35, and Eamon Byrne, 39. Five others were wounded.
Family members packed the High Court in Belfast for Friday's hearing.