Police assessed it was possible that dissident republicans would use firearms to attack officers if the Drumcree parade passed along the Garvaghy Road in Portadown, Co Armagh, the High Court in Belfast has heard.
During a legal challenge to a decision by the Northern Ireland Secretary Chris Bryant to ban the parade, a barrister said the Police Service of Northern Ireland (PSNI) had been dealing with a “developing and potentially extremely serious public order situation”.
Members of the Orange Order are seeking a judicial review after Bryant halted the parade from going along the mainly nationalist Garvaghy Road amid large-scale protests by residents opposed to the procession.
His decision followed a two-week stand-off.
The application for judicial review against that decision is being heard at the High Court.
It includes a challenge to the decision by PSNI chief constable Jon Boutcher to ask Bryant to review the determination made by the Parades Commission, which had given the go-ahead for the parade.
During the hearing, barrister Richard McConkey, who represents a member of the Orange Order who has brought the challenge, read from an intelligence assessment provided by the chief constable to Bryant about the security situation.
The barrister said the assessment had said it was “almost certain” the parade would be accompanied by a protest on the Garvaghy Road.
McConkey said: “It continues: ‘It is highly likely that persons will continue to travel to Garvaghy Road from across Northern Ireland to support protest activity and it is highly likely that the protest will continue to involve significant numbers of persons, and will continue to seek to block the road to prevent a parade in Garvaghy Road’.”
McConkey said the assessment then recorded “significantly more serious” intelligence.
“It went on: ‘It is almost certain that dissident republicans have attended the protest, and it is possible that dissident republicans have already accessed the firearms in the Garvaghy Road area, and it is possible that in the event of police removing protesters, firearms may be used to attack police.’
“There is then reliable intelligence indicating that mainstream republicans are concerned about their ability to prevent disorder or control dissident republicans, and it remains likely that the police intervention will be met with serious disorder, which may involve the use of petrol bombs.”
The barrister said police were “assessing a developing and potentially extremely serious public order situation”.
The case continues.