Inquests for the Birmingham pub bombing victims will not resolve the "enduring injustice" for victims and families, an appeal hearing has been told.
Coroner Sir Peter Thornton QC is challenging a ruling which said he was wrong to decide the names of suspects would not be part of the new inquests.
Two bombs exploded in the city centre in 1974, killing 21 people.
In January, High Court judges quashed a decision to exclude the "perpetrator issue" from the hearings.
The bombings are widely believed to be the work of the IRA, making it the deadliest peacetime attack in the UK at the time.
Lawyers representing the families said there was the "most pressing need for a thorough investigation".
At the Court of Appeal on Tuesday, Peter Skelton QC, who is representing Sir Peter said: "The 21 people who died in the bombings and their families have suffered an enduring injustice.
"The pain and grief they have borne has been exacerbated by the fact no-one has ever been held accountable in law.
"But, for the reasons the coroner gave... these inquests cannot resolve the enduring injustice."
Victims' families are arguing it is necessary for the inquests to investigate the perpetrator issue because the police investigation into the bombings resulted in a "notorious miscarriage of justice".
The Birmingham Six were jailed for the murders and served 17 years behind bars before their convictions were quashed.
Five West Midlands Police officers were charged with perverting the course of justice in connection with the original criminal investigation, but a judge ruled in 1993 that a fair trial would be impossible.
Analysis: Sima Kotecha, BBC News
Still no inquest date - and still no idea what the scope of the inquest will entail.
Today's arguments at the court of appeal involved going over some of the ground that's been heard before but it's a step closer to resolving the long running issue of whether the inquest should involve discussion of who was behind the attacks and why.
However, the appeal judges could take several weeks - if not months - to make a decision.
The latter undoubtedly will cause more frustration among some of the families who have fought for years for an inquest into the 21 deaths to be reopened.
Hugh Southey QC, representing the families, said: "There has never been an effective and independent investigation into who was responsible for the atrocity.
"There is no prospect of such an investigation occurring, apart from within the inquest.
"Despite that, the appellant decided not to investigate the issue of who was responsible."
Lord Chief Justice Lord Burnett, Lady Justice Hallett and Lord Justice McCombe are expected to give their ruling at a later date.
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