A former British Army agent who infiltrated republican paramilitary ranks has lost a High Court battle over being refused key status at the Omagh bomb inquiry.
Peter Keeley claimed the decision to reject his application was irrational and taken without any proper explanation.
But a judge ruled on Friday that his challenge was “unarguable”.
Mr Keeley, an ex-spy who used the pseudonym Kevin Fulton, issued judicial review proceedings after being denied core participant status at the public inquiry set up to establish if state authorities could have prevented the Omagh bomb atrocity.
Twenty nine people, including a woman pregnant with twins, were killed in the Real IRA attack on the town in August 1998.
Mr Keeley has claimed he warned his Special Branch handlers about dissident republican plans in the days before the explosion.
His allegations featured in a highly critical Police Ombudsman report in 2001 about how the RUC dealt with intelligence and investigated the bombing.
Despite concluding that Fulton had passed information to the police between June and August 1998, it made no specific reference to a bomb being destined for Omagh.
Sir Ronnie Flanagan, chief constable at the time, vehemently rejected the ombudsman’s findings and insisted nothing could have been done to prevent the attack.
Refuting some of the report’s conclusions as being flawed and inaccurate, police claimed Fulton was unreliable and any intelligence he supplied was of no significance to the Omagh bombing.
The public inquiry, chaired by retired judge Lord Turnbull, is expected to examine any information on dissident republican terrorist activity he passed to police in the months leading up to the attack.
Anyone granted core participant status at the inquiry is entitled to make opening and closing statements, suggest lines of questioning and receive relevant material.
Mr Keeley claimed he had been unfairly deprived of those rights given the inevitable attacks on his credibility.
Lawyers representing the former spy also argued that the chairman’s decision to instead give him witness status was arbitrary, irrational and “high handed”.
The only discernible reason was the potentially large number of people and organisations who could claim a significant interest in the subject matter of the inquiry.
Counsel for the inquiry responded that the determination was reached following a process which was “conspicuously fair”.
Backing those submissions, Mr Justice Humphreys described the former agent’s criticisms as misplaced.
He held that the chairman was entitled to reach his conclusions and to conclude that Mr Keeley will still be able to effectively and fairly participate in the inquiry.
“It is not arguable that the decision to refuse core participant status to the applicant was irrational, either in the sense that immaterial considerations were taken into account, or that the decision defied logic,” he said.
Dismissing Mr Keeley’s challenge, the judge rejected further allegations that he was not given a proper explanation why the requested status was refused.
“It was because the chair determined his proper status was that of a witness in light of all the issues and questions which the inquiry would have to address,” Mr Justice Humphreys added.
“The applicant’s reasons challenge is therefore unarguable.”