Justice minister Dermot Ahern has no plans to release infamous murderer Malcolm MacArthur – who has been in prison for 26 years – despite the fact that the average prison sentence served by a murderer here is 17 years, almost a decade less than MacArthur has served.

Ahern told the Sunday Tribune that "there is nothing on the horizon" concerning MacArthur's possible release from Shelton Abbey open prison in Wicklow.

Lawyers for MacArthur are due before the High Court shortly seeking to compel the state to enter a defence against his claims that he should be released under a parole-board recommendation. He maintains his continued detention breaches his rights under the constitution and the European Convention on Human Rights.

His legal team will argue that parole-board recommendations should be given greater weight by the justice minister. "There is a strong feeling that it's utterly unacceptable that criminal-justice decisions are made by politicians," according to a legal source. "Politicians make decisions based on popularity and it would not be a popular decision to allow MacArthur out of prison. Anything to do with the administration of justice should be dealt with by the judiciary."

It is understood that MacArthur, who was temporarily released on Christmas Day, is anxious for his freedom. He is currently the second-longest-serving prisoner in the Irish prison system, for the brutal killing of nurse Bridie Gargan in the Phoenix Park in 1982, but he was never pursued for a second murder. Days after MacArthur's crazed attack on Gargan, he shot dead farmer Donal Dunne with Dunne's own gun near his home in Edenderry, Co Offaly.

MacArthur was later arrested in the home of former attorney general Patrick Connolly.

The series of events leading up to his arrest attracted major controversy and were described by then taoiseach Charles Haughey as "grotesque, unbelievable, bizarre and unprecedented". As a result, it was coined the Gubu affair.

After a remarkable trial that lasted just five minutes, MacArthur was sentenced to life imprisonment, which at that point meant between 10 and 12 years in prison. There was public outrage after it emerged that he would not face trial for the murder of Dunne when the DPP dropped this charge.

Ahern said one of the most difficult aspects of his job as justice minister is reviewing parole cases and deciding to let convicted murderers out of prison when his "instinct" was to leave then behind bars.

"A difficult area in this job is deciding to let people out and hoping in God's name they don't re-commit an offence," he said. "As long as I'm minister, the average [life sentence] will be going upwards not downwards." Ahern added that decisions to release life-sentence prisoners depended on the circumstances of the crime.

John Banville's Booker-shortlisted 1989 novel The Book of Evidence was inspired by the MacArthur case.

"I believe very strongly indeed that the judiciary and not the minister for justice should decide on when to release prisoners serving life sentences," Banville told the Sunday Tribune.