Sinn Féin President Gerry Adams has launched a legal bid to overturn two historical convictions for attempting to escape from prison.
Appeal proceedings began before three senior judges at Belfast's Royal Courts of Justice today.
Mr Adams, now a Louth TD, is seeking to quash convictions received in 1975 while he was interned without trial at the Maze Prison during the early 1970s.
Barrister Sean Dorian QC, who is representing the veteran politician, said: "Each conviction is for attempting to escape from lawful custody."
The case centres on a technicality that Mr Adams' internment was not lawful because the order to detain him had not been considered by the then Secretary of State.
Mr Doran said documents presented to the Appeal Court judges appeared to "copper fasten submissions that there was not personal consideration of the case".
The court heard how an interim custody order had been signed by a junior minister at the Northern Ireland Office and not the Secretary of State.
"There is a very clear distinction in the power to make an order and the power to sign an order," added Mr Doran.
Earlier the court was told how Mr Adams, who was not in court for the hearing, was twice convicted of attempting to escape from the Maze.
On Christmas Eve, 1973, he was among four detainees caught attempting to break out.
"A hole had been cut in the perimeter fence and all four were already through," said Mr Doran.
The second escape bid in July 1974 was described as an "elaborate scheme" which included the kidnap of a man, who bore a "striking resemblance" to Mr Adams, from a bus stop in west Belfast.
The man was taken to a house where his hair was dyed and he was given a false beard, the court heard.
He was then taken to the Maze Prison where he was to be substituted for Mr Adams in a visiting hut. However, prison staff were alerted to the plan and Mr Adams was arrested in the car park of the jail, the court heard.
Mr Adams was among hundreds of republicans to be held without trial during the height of the Troubles.
Internment was introduced in 1971 by the UK's former Northern Ireland Prime Minister Brian Faulkner for those suspected of involvement in violence.
Mr Adams was interned in March 1972, but was released in June that year to take part in secret talks in London.
He was rearrested in July 1973 at a Belfast house and interned at the Maze Prison, also known as Long Kesh internment camp.
Both of his convictions were handed down by two separate Diplock Court trials - cases tried by a single judge sitting without a jury.
In the first wave of raids across Northern Ireland, 342 people were arrested.
The policy of internment lasted until December 1975. During that time, 1,981 people were interned - 1,874 were nationalist and 107 were loyalist.
The introduction of internment, the way the arrests were carried out and the abuse of those arrested led to mass protests and a sharp increase in violence.