The daughter of a man killed in what became known as the "Good Samaritan" bomb has said a new inquest would help her find closure.
Phyllis Keeley, whose father Eugene Dalton was blown up in an IRA bomb attack in Londonderry almost 30 years ago, hopes to force Northern Ireland's chief legal officer to overturn his decision not to order a fresh probe.
S he said: "It's not just about frustration. It's about trying to find some sort of closure. And we cannot move forward until we get to the truth."
Ms Keeley and other relatives are due to take their case to Belfast High Court on Monday.
If successful, it would mark the first time the decision-making powers of Attorney General John Larkin QC have been tested in court and could have major implications for a number of Troubles-related cases.
Mr Dalton, 54, was one of three people killed when the IRA booby trap device detonated at a flat in Derry's Creggan estate as they checked on the welfare of a neighbour.
Sheila Lewis, 68, was also killed in the explosion while Gerard Curran, 57, died seven months after being pulled from the rubble.
The IRA later apologised, admitting they left a bomb inside a Wellington boot in the flat hallway to kill members of an army search team.
In 2013, a Police Ombudsman investigation found the Royal Ulster Constabulary (RUC) had sufficient information and intelligence that some sort of device had been left in the vicinity of the flat - but did not alert anybody about the threat even though the area was declared out of bounds to officers.
The Ombudsman said while responsibility for the deaths rested with the people who planted the bomb police had failed to protect the victims and the subsequent murder investigation was flawed, inadequate and incomplete.
Ms Keeley said: "My father was a good man. He was a very helpful and good neighbour - in fact that's how he was killed - going to check on a neighbour.
"He was recently bereaved, having lost my mother just five weeks earlier.
"His death was awful for us at the time and it still is.
"He cannot speak for himself now so, it is up to us to fight for justice and the truth about what happened to him."
Mr Larkin has the power to direct a new inquest in cases where the original inquest has been deemed inadequate or because new evidence has come to light.
He may also take into account the failure of other mechanisms of investigation such as the Police Ombudsman or the now defunct Historical Enquiries Team.
In a statement, KRW Law which is representing Mr Dalton's family said: "The inquest process is an important element of the mechanisms to achieve justice, truth and accountability for the human violations suffered during the conflict.
"In the absence of a human rights compliant mechanism of investigation into all conflict-related deaths and injuries, families such as that of Eugene Dalton are forced to battle for truth, justice and accountability through the courts including against the decisions of law officers within who they should have the ability to trust for fair and reasonable decision-making, without the influence of any personal opinion."
The Attorney General has previously ordered new hearings for a number of controversial legacy cases including the deaths of 10 people in Ballymurphy, West Belfast in 1971 and of 11-year-old Francis Rowntree who died days after being hit by a rubber bullet in the Divis area of West Belfast in 1972.
Meanwhile, the Dalton family are also involved in legal proceedings against the British Government because the bomb contained Libyan-supplied Semtex.