A convicted murderer who fled to the United States after taking part in the mass IRA Maze prison escape 36 years ago has secured the right to mount a renewed legal bid to clear his name.
Senior judges in Belfast backed Kevin Barry Artt's claims that he never formally abandoned his appeal.
The 59-year-old is seeking to overturn a verdict that he was guilty of killing the Maze Prison's deputy governor Albert Miles in 1978.
His case will now proceed to a full hearing at the Court of Appeal later this year.
Artt has remained in California since a failed attempt to extradite him.
Defence lawyers are set to argue that police conduct during his interrogation and flaws in the trial process render his conviction unsafe.
In 1983 Artt was sentenced to life imprisonment for the IRA murder of Mr Miles.
The victim had been gunned down in front of his wife at their home off the Cavehill Road in north Belfast.
A month after lodging appeal papers, Artt joined 37 other inmates in the September 1983 escape from the Maze - the biggest jailbreak in UK history.
He fled to America, settling on the west coast and establishing himself as a successful car salesman.
In 1992 he was arrested on a passport violation, leading to the British authorities seeking his extradition.
But following a protracted process the US courts ruled against sending him back.
His lawyers have prepared fresh grounds on which they contend the conviction should be quashed.
They claim the only evidence implicating him came from admissions made under duress at the Castlereagh police detention centre.
The case is also expected to focus on forensic ESDA tests of the original handwritten police interview notes, a process carried out for the extradition proceedings.
Outside court, Artt's solicitor Fearghal Shiels welcomed the decision reached on the preliminary issue.
He said: "We are pleased that the court accepts that Mr Artt did not abandon his appeal, and he now looks forward with confidence to his substantive appeal hearing."
