A prisoner who was viciously slashed by another inmate in an unprovoked attack has been awarded €150,000 in damages by the High Court.

He is the first person to be awarded damages by the High Court for injuries sustained in an attack while in custody.

Peter Creighton was serving a sentence in Wheatfield prison in 2003 when he was attacked in an overcrowded area used for inmates receiving methadone.

He suffered severe lacerations to his face and body - totalling 78 centimetres - and was scarred for life.

Mr Creighton sued the state for negligence and breach of duty claiming the system for bringing prisoners from the cells to receive methadone was dangerous.

The overcrowding in the space facilitated attacks of that kind, he claimed.

He also said there should have been adequate security measures to prevent the kind of knives used in the attack from getting into the prison.

The State had rejected the criticisms and said all necessary care was taken to ensure the safety of the plaintiff.

Lawyers for the State also contended it was not possible in a prison, an inherently dangerous place, to guarantee the safety of a prisoner and ensure his protection from attacks by other prisoners.

Mr Justice Iarfhlaith O Neill said there could be few tasks, if any, that are more difficult than the management of the prison system.

In terms of control and management of people, prison populations were the most difficult cadre of people to manage, he said.

"On a daily basis prison staff must constantly apprehend and cope with the threat if not the actuality of the most extreme violence," he said.

He said the courts would not impose upon prison authorities' a duty of care that was not capable of being performed.

However when there were systems or practices which have obvious deficiencies and foreseeable risks to the safety of prisoners, it behoves the court to intervene, he said.

The practice of congregating large numbers of prisoners in a space used to wait for methadone breached the prison authorities' duty of care to the plaintiff.

He said having regard to the long history of material being thrown over the wall of the prison it was hard to comprehend why it was not until 2007 that the obvious precaution of netting was introduced.

He was satisfied the defendants failed in their duty to the plaintiff in allowing 15 prisoners into the same space to await methadone and in failing to have netting erected around the perimeter of the yard as a consequence of which the knife used to attack the plaintiff was brought into the prison.

He said the plaintiff had been left with disfiguring scars which he has had to live with since the age of 24 and for the rest of his life.

He awarded €100,000 for the injuries to his face and €50,000 for the injuries to his body.

Solicitor Gerry Burns said it was a significant judgment which established a duty of care on the part of prison authorities for prisoners.

He said Mr Creighton was pleased that today's judgment brought closure to a very long trial which had been ongoing since 2003.

The case had previously been before the High Court and appealed to the Supreme Court but was returned to the High Court to be re-tried. Today's judgement could be appealed by the State.