A former army private is suing the department of defence for negligence that led to him being sexually assaulted by a superior officer.

The man is claiming that the army failed to prevent the assault being perpetrated on him. He is also suing the officer who abused him, the state and the Attorney General.

The abuser, former Sergeant Major Patrick Devereux, was convicted in 2006 of six counts of sexual abuse in the Dublin Circuit Criminal Court. He pleaded guilty and received a two-year suspended sentence after tendering €15,000 to the court.

The plaintiff in the action, which is due to open in the High Court on 21 October, is claiming that the army "failed to take any reasonable steps or precautions" for his safety.

He also claims they failed to "monitor the behaviour of the first named defendant (Devereux) when they knew or ought to have known that he was engaged in conduct of an unlawful and immoral nature".

The man is also claiming that the army failed to discipline Devereux when they knew or ought to have known that there were complaints being made against him. The army's failure to provide or maintain a sexual harassment policy is also cited.

The former private was subjected to the abuse at McKee Barracks in Dublin in 1999 when he was 18 years of age, within 12 months of joining the army. He was called into Devereux's office to see how he was coping after his sister had a stillbirth and he himself was mugged by a thief wielding a syringe in the space of a few weeks.

He was abused on that occasion and on four or more others. He told a garda investigation that Devereux said he "would make his life hell" if he revealed what had happened. The following year, the private left the army without permission as a result of trauma.

He went to the gardaí and made a complaint about the abuse. The gardaí were obliged to return him to his barracks, and when he was brought back he was locked in a guard room for two days.

He was then brought before his commanding officer whom he told he wanted out of the army and was given an honourable discharge due to his circumstances.

The action being taken against the Department of Defence is one of the first of its kind in the state. Over the last decade similar actions have been taken against the state, the department of education and various religious orders.

The hearing is expected to last two weeks.