A lawyer for Boutcher said the PSNI assessment was that all “lawful and proportionate options” to facilitate the parade had been “exhausted”.

Any attempt to police it “would have involved substantial public order intervention”.

He said Boutcher believed this would have carried an “unacceptable risk” of serious and prolonged disorder, with “a wider contagion effect”.

The request for Sir Chris to intervene had been based on operational policing considerations and is “devoid of any public law wrong”.

The lawyer said: “He (Boutcher) was putting the situation in the Secretary of State’s hands.”

He said Boutcher, when pointing out the consequences for Stormont and the peace process, had been making an “observation”.

“No-one is saying he woke up one morning and imagined all these potential consequences.

“These are real life consequences everybody was thinking of.”

A lawyer for Sir Chris later introduced another element of the police intelligence assessment.

He told the court that it stated that loyalist paramilitaries were “depicting signs of frustration” and that it was “highly likely” that increasing numbers of loyalists would attend the Portadown area.

The intelligence stated “disorder at Drumcree Church remained a possibility”.

The lawyer added: “Both sides were converging on the area.”

Monday’s legal challenge was originally scheduled for last week, but was delayed after the Orange Order added the chief constable to the case.

The case is being brought by a Portadown Orangeman against Sir Chris Bryant and Chief Constable Jon Boutcher.

Sir Chris’ intervention ended a two-week stand-off after the parade route on Garvaghy Road was blocked by protesters.

Boutcher has said the parade could have caused serious disorder, with “catastrophic” consequences for Stormont and the peace process.

The applicant has alleged Boutcher had taken into account “wholly political” considerations, which were “immaterial” to policing decisions.

It is claimed these invalidated his advice and “infected” the secretary of state’s decision and Sir Chris showed “scatter gun decision-making” and had “misdirected himself”.

It is also alleged he made “a fundamental error” in giving equal weight to a lawful parade and an unlawful protest.

At the outset of the hearing, Mr Justice Scoffield told the court that he would reach a “swift” decision either later this week or next.

The hearing will resume on Tuesday.