The only man charged in connection with the murder of prison officer David Black has launched a High Court bid to overturn an order for him to stand trial.
Lawyers for Damien McLaughlin claimed the decision should be quashed because he was unfairly denied the chance to cross-examine a key prosecution witness.
They also contended that a district judge who committed him for trial applied the wrong legal test.
McLaughlin, 39, from the Kilmascally Road in Dungannon, is facing four charges in relation to the prison officer’s killing.
They include aiding and abetting his murder, having a Toyota Camry car for use in terrorism, preparing a terrorist act by starting and moving the vehicle which the killers used, and belonging to a proscribed organisation, namely the IRA.
Mr Black was shot dead on the M1 in Co Armagh in November 2012 en route to work at high-security Maghaberry Prison.
The 52-year-old father of two was the first Northern Ireland prison officer to be murdered in nearly 20 years.
The prosecution alleges McLaughlin transported the Toyota car across the Irish border on the eve of the attack.
In June last year a preliminary investigation resulted in the district judge ordering him to be returned for trial.
But McLaughlin’s legal team are now seeking to have the decision judicially reviewed.
Their challenge centres on statements from a man who was arrested and interviewed by the Garda as a suspect in the murder plot.
He was not called as a witness during the preliminary investigation.
Barry Macdonald QC, for McLaughlin, told senior judges: “What we are talking about here is a statutory right to cross-examine witnesses before trial.”
His client, who is currently on bail, was in court for the legal challenge.
Philip Henry, representing the prosecution, argued that the proceedings were a form of satellite litigation.
He also stressed that the district judge was not deciding on the issue of guilt or innocence.
Following submissions Lord Chief Justice Sir Declan Morgan and Mr Justice Maguire reserved their verdict.
Sir Declan pledged: “Given this case remains to be dealt with, we will try to give judgment before the end of term.”