Mrs Pemberton had long been a victim of domestic abuse

Julia Pemberton and her son, Will, 16, were killed by Alan Pemberton, who then shot himself, at their Berkshire home.

Pemberton, separated from his wife, had been banned from going to the house.

Frank Mullane, 44, of Wiltshire, believes Thames Valley Police failed to take steps to prevent the murders in November 2003, despite warning signs.

He wants the terms of the proposed inquiry to be wider under Article 2 of the European Convention on Human Rights - the right to have life protected by law.

Test case

The review, said to be the first of its kind, could shape how investigations into similar tragedies will be carried out in the future under the new Domestic Violence, Crime and Victims Act - which introduces homicide reviews in domestic violence cases.

On Wednesday, Mr Justice Walker, sitting in London, ruled there was an arguable case which should go to a full hearing in the near future.

A homicide review into the case was established after Mr Mullane, from Swindon, met Home Office Minister Baroness Scotland last year.

The proposed inquiry into the case will be conducted by the West Berkshire Safer Communities Partnership - an organisation comprised of local agencies including the police, the health service and the council.

The partnership has denied it has a duty to hold a probe under Article 2 into whether failings by the police or any other agents of the state may have contributed to the two deaths.