Gerry Adams has been accused in the High Court of being "directly responsible for and complicit" in decisions by the Provisional IRA to detonate bombs across England.
The former Sinn Fein president arrived at the Royal Courts of Justice on Monday wearing a bullet-proof vest, and was driven into the car park.
Three victims of IRA bombings – John Clark from the 1973 Old Bailey attack, Jonathan Ganesh from the 1996 London Docklands explosion, and Barry Laycock from the 1996 Arndale shopping centre bombing in Manchester – are bringing legal action.
They allege Mr Adams was a leading member of the Provisional IRA, including its Army Council, during these periods.
The men are seeking nominal damages of £1 from Mr Adams.
Mr Adams denies that he had any role in the Provisional IRA and is opposing the claim.
The court in London heard that the three men want to show how Mr Adams was involved in the Provisional IRA “in the course of that conflict and to show on the balance of probabilities that he was as involved as the people who planted and detonated those bombs”.
Opening her case on Monday, Anne Studd KC, representing the men, also said Mr Adams was “directly responsible for and complicit in those decisions made by that organisation to detonate bombs on the British mainland in 1973 and 1996”.
In written submissions, Ms Studd said: “The defendant carefully draws a distinction between being a member of ‘the Army’ and being a member of Sinn Fein.
“In reality, the evidence will demonstrate that this was not the clear either/or choice as the defendant would have you believe.
“For many individuals, we say, including Mr Adams, that was a distinction without a difference.”
Ms Studd told the court that a “jigsaw” of evidence from those who knew Mr Adams and those who knew of him will prove the case against him.
She added: “The claimants’ case is that none of these bombings in the United Kingdom mainland took place without the knowledge and agreement of the defendant in his role in the Provisional IRA and latterly as a member of the seven-man Army Council.”
She concluded: “There is no doubt that the defendant contributed to the peace in Northern Ireland, but the claimants say that on the evidence he also contributed to the war.”
Ms Studd also told the court that Mr Adams had “a foot in each camp” of the military and political sides of the Irish Republican movement.
She said: “What we have here are witnesses who give evidence about intelligence that they saw amassed over years.
“It provided details of the structure of the Provisional IRA, the election of the army executive and the appointment of those executive members of the seven-person Army Council.
“The Army Council set the strategy for the Provisional IRA through all the years of the Troubles. It did not really change in its basic information, which was that the defendant was an instrumental force in the organisation of the Provisional IRA and building of the two-strand attack – Armalite and the ballot box.”
Lawyers for Mr Adams, who denies the claims, said Mr Adams “played an instrumental role in the peace process which culminated in the signing of the Good Friday Agreement in April 1998, which brought an end to the decades-long conflict”.
In written submissions, Edward Craven KC, representing Mr Adams, said: “The defendant’s alleged factual and legal responsibility for the claimants’ injuries is strongly contested, as is the claimants’ ability to bring these claims against the defendant several decades after the expiry of the applicable limitation period.”
He added that there is “no legal or practical reason why these claims could not have been issued long before 2022”.
Mr Craven continued: “Even if the claim were not bound to fail on limitation grounds, the claim must inevitably fail on the merits.
“The defendant strenuously denies any involvement in the bombings.”
He also said: “The defendant has never been arrested on suspicion of, still less charged or convicted of, any offence in connection with any of the bombings.
“Had law enforcement authorities been in possession of information which created a reasonable suspicion that the defendant may have been involved in those bombings, he would have been arrested and questioned.”
The trial before Mr Justice Swift is expected to end next week.
