The 1998 explosion killed 29 people and unborn twins
In the absence of a criminal conviction for the 1998 Omagh bomb, six families of the victims took a civil action to seek damages from the men they believed were responsible for the atrocity. Freya McClements from BBC News looks at the legal precedents set by the groundbreaking case.
The Omagh civil case is believed to be the first time anywhere in the world that alleged members of a terrorist organisation have been sued.
Lord Daniel Brennan QC, acting for the families, described it as "a unprecedented civil action".
"For the first time, private citizens are confronting terrorists in our courts," he said.
Victor Barker lost his 12-year-old son James in the bomb.
"This particular case is of public significance," he said.
"It is the public saying to people engaged in terrorism that they no longer want that path to be followed."
The 14-month case has been marked by similar legal firsts.
In an unprecedented step, the hearing was relocated from Belfast to the Supreme Court in Dublin in May so that evidence could be heard from Irish police officers.
It was the first time a judge from Northern Ireland had travelled to the Republic of Ireland on official business.
The case was also the first time that the British government had helped to fund a civil action.
In 2003 it contributed £800,000 towards the £1.5m needed to launch the action.
At the time, a government spokesman said it was because the situation was "totally exceptional".
The former Northern Ireland secretary Peter Mandelson, who campaigned on behalf of the families, said the government had "done right" by the Omagh families.
"It would have been morally indefensible to have extended funding to the defendants but not give a penny to the legal fund mounted by the families."
In 2008 two of the defendants, Colm Murphy and Seamus Daly, lodged an appeal against exceptional legal aid being granted to the victims' families.
They said a public pledge of financial assistance to the families ahead of any legal authorisation was predetermining the outcome of the legal process.
But the Court of Appeal ruled it could not be assumed the government had abandoned its fair and independent judgement.