A man serving life for the murder of a van driver more than 20 years ago claims he should not have been transferred from an open prison back to a high security jail over a decision that he had taken drugs - which he denies.
Alan Lyons (38), formerly of Bonham Street, Dublin, says he was unwell from a blood disorder and not "stoned" as prison authorities believe.
He was jailed in 2000 for the murder of David Watson (21), a Liverpool man working as a van driver in Dublin, in a fatal stabbing during an attempted mugging on Thomas Street.
Mr Lyons has brought a High Court challenge to his transfer from Shelton Abbey open prison in Wicklow back to Wheatfield in Dublin for allegedly having taken drugs on two occasions in October 2016 and July 2017.
He wants the decision quashed as arbitrary, capricious or unjust.
Prison authorities said his speech was slurred and he was unsteady on his feet on both occasions.
He denied his speech was slurred but says he was unwell due to a disorder of iron overload in the blood, called Haemochromatosis.
He said he can appear similarly unwell to this day due to conditions that doctors are still investigating, including possible Lyme disease.
The court heard urine tests taken on both occasions, after he was sent back to Wheatfield, proved negative.
He claims the return to the high security prison has been detrimental to his mental health and disrupted the progress he has made while in prison. He has got an Open University honours BA in humanities and was attending a music course at a Bray college.
He has a relationship with a woman he knew before he went to prison and hopes to have a family when he gets out.
"My hope and stuff for the future nearly went out the window", he said in relation to how the transfer affected him.
In 2000, the Central Criminal Court heard David Watson, who lived in Dublin with his fiancee, had parked his employer's van at a junction in Thomas Street on the night of April 24. He had been drinking and was slumped at the wheel when a number of people leaving a pub told him to move the van.
Mr Watson moved it and a witness heard someone say "this would be an easy mug". When Mr Watson got out of the van to defend himself against three or four people who were attacking him, he collapsed having been stabbed.
Another witness said they heard Lyons say shortly afterwards: "I got rid of it", a reference to the murder weapon.
Mr Lyons, who denied murder but admitted manslaughter, was sentenced to life.
The High Court heard today that he became a model prisoner over the years and in 2016, the parole board recommended he be transferred to an open prison.
Shelton Abbey's assistant governor, Patrick Corcoran, told the court he observed Mr Lyons unsteady on his feet on two occasions, both just weeks after he had come from Wheatfield.
He believed he was under the influence of drugs and for his own health and safety, and because there are only limited medical facilities in Shelton Abbey, he decided to transfer him.
Mr Lyons told the court he was not wobbling or falling down but was "unwell" and "a bit worse for wear".
He denied he was present when officers carried out a search of his Shelton Abbey room on the day of the second incident.
He agreed he had a smart mobile phone in his room, rather than a basic model which was all he was entitled to. He denied he put something into his mouth while officers were searching his room.
The case resumes next month before Mr Justice Charles Meenan.