The European Court of Human Rights has ruled a civil case brought against two men accused of involvement in the Omagh bombing was conducted fairly.
Twenty-nine people including a woman pregnant with twins were killed when a 500lb bomb detonated in the Tyrone town on August 15, 1998. It was the single biggest atrocity of the Troubles.
Families of the victims took a successful civil case against convicted Real IRA chief Michael McKevitt and Co Louth man Liam Campbell - both of whom are currently imprisoned - and the two men were ordered to pay £1.6m in damages, along with two others.
The men appealed the ruling to the European Court of Human Rights, arguing that the civil trial in Belfast High Court had been unfair. They said the judge should have applied a criminal rather a civil standard of proof, due to the severity of the allegations, and further claimed that the evidence of an FBI agent heard during the trial should not have been admitted.
The European Court this morning unanimously threw out the application for the case to be overturned. The seven ECHR judges made clear their decision was final.
"The applicants had not demonstrated that their trial was unfair, and the Court dismissed their applications," said an ECHR statement.
No one has ever been found to be criminally responsible for the bombing.
The ECHR case was the latest in a series of separate legal attempts by the four defendants to overturn the 2009 civil judgment.
The relatives who took the action are still pursuing the damages.
One of the key witnesses in the families' case was FBI agent David Rupert, who had infiltrated the Real IRA.
He did not attend the trial in person due to concerns about his security and medical condition.
McKevitt and Campbell argued that their lawyers' inability to cross-examine Mr Rupert had been unfair.
The ECHR dismissed this argument, insisting the trial judge had taken the "appropriate safeguards and considerations" in dealing with the evidence of an absent witness.
The applicants also claimed the judge should have applied a criminal standard of proof - beyond reasonable doubt - rather than a civil one - balance of probabilities - due to the severity of the allegations facing them.
The European judges said that was not necessary because the proceedings had been for a civil claim for damages and there had been no criminal charge involved.
Rejecting both grounds for the application, the ECHR said: "The Court found that the national court's findings could not be said to have been arbitrary or unreasonable."