The Police Service of Northern Ireland is seeking all media footage from an outbreak of violence in north Belfast this summer as it emerged masked rioters hadbeen identified because they drop their cover for smoke and drink breaks.
Police disclosed the slip-up as lawyers for the PSNI appeared at court requesting an order for full production of unbroadcast material and photographs taken during 12 July disorder in the Ardoyne area.
The BBC, Ulster TV, Sky News and the Press Association joined forces in resisting the application at a hearing at Belfast Recorders Court yesterday.
Rioting erupted followed a contentious Orange Order parade and counter-demonstration by nationalist residents.
Twenty PSNI officers were injured and 17 shots were fired at police lines.
Up to 90 people were involved in the trouble.
A detective sergeant in charge of the evidence gathering operation told the court more than 30 suspects have so far been arrested.
The court heard that film of the gunman was obtained from YouTube and aerially from a police helicopter. It showed him emerging from the crowd, opening fire and then running back. He had not been identified.
The detective claimed unused material might hold evidential value, even though it was not regarded as newsworthy.
During cross-examination he disclosed how police have managed to name some of those responsible for the attacks.
"Individuals wearing masks take a smoke break or take a drink," he said.
"Luckily we have been able to get identifications whenever they drop their guard slightly."
The Recorder for Belfast, Judge David McFarland, was told police evidence had in the past been significantly enhanced by images captured by media organisations.
Earlier this year the High Court in London quashed a production order that would have forced broadcasters to hand Essex Police unused footage of the Dale Farm traveller site evictions.
The Divisional Court held that those applying for such orders had to show a "clear and compelling case", backed by clear and specific evidence that production of material was necessary.
That ruling is being seen as potentially shifting the balance towards media organisations in legal battles over disclosure of their unbroadcast and unpublished material.
News chiefs representing the BBC, Ulster TV and Sky all testified yesterday that camera crews covering the riots were instructed not to go beyond police lines.
Sky's senior Ireland correspondent David Blevins, who was at the scene of the trouble, said his organisation's material has no further evidential worth.
He said: "I don't believe it would be of any greater assistance in identifying offenders on the night in question."
The court reserved judgment.