The public has a right to know if one State agent was allowed to murder another to advance within the IRA, a court has heard.
Lawyers for a husband and wife seeking full reasons why prosecuting authorities now accept their convictions for offences linked to the killing of a police informer should be quashed, claimed non-disclosure could lead to more wrongdoing.
Senior judges were also told PSNI and Police Ombudsman investigations into RUC and military behaviour in the case of James Martin and Veronica Ryan are now under way.
The west Belfast couple were both convicted of the false imprisonment of Joe Fenton, a Special Branch agent shot dead after being lured to a house in the city in February 1989. Mr Martin, who was also found guilty of making property available for terrorism, was later sentenced to four years imprisonment. His wife, formerly known as Veronica Martin, was jailed for six months.
Their case was referred back to the Court of Appeal.
Last year it emerged that Director of Public Prosecutions Barra McGrory believes the guilty verdicts should be quashed.
But a Public Interest Immunity Certificate has been obtained to protect a confidential dossier containing relevant material.
Lawyers for the couple are now seeking a full and open judgment when judges decide whether to overturn their convictions.
Sean Devine, counsel for Mr Martin, said the public deserved to know about secretive behaviour.
He told the court there was one man at the centre of the case, saying: "If the speculation is correct and it's the case that one agent of the state was allowed to execute another agent of the state to enhance his position with a paramilitary organisation so he could provide a higher grade of intelligence, that needs to be stated."
Referring to the alleged mishandling of agents, he argued that higher standards are expected from the authorities.
"If it's the case that there was some profoundly embarrassing behaviour, and there may been be widespread repercussions, it's better to lance the boil rather than to leave communities and individuals speculating about what went wrong," he claimed. "There's been the destruction of lives and that can't be remedied by more secretive behaviour on the part of other public authorities."
But Gerald Simpson QC, for the prosecution service, contended that the case for delivering a closed judgment was "overwhelming", and rejected claims that such a verdict would endorse any wrongdoing.
The three-judge panel reserved their decision on the application.