The organisation led by convicted Real IRA leader Michael McKevitt was responsible for "murder and mayhem on this island", the Court of Criminal Appeal was told yesterday.
Opposing McKevitt's appeal against his conviction for directing terrorism, senior counsel George Birmingham, for the Director of Public Prosecutions, said McKevitt's organisation was responsible "for the murder of men, women, children and unborn children and has sought to subvert the Constitution of this State".
Mr Birmingham said the State was obliged by the Constitution and by international agreements to bring the particular individual who led that organisation to trial.
McKevitt (54), Beech Park, Blackrock, Co Louth, was jailed for 20 years by the Special Criminal Court in August 2003 after he was convicted of directing the activities of a terrorist organisation between August 29th, 1999, and October 23rd, 2000. He was the first person to be convicted in the State for the offence, which was introduced after the Real IRA bomb attack in Omagh in 1998 in which 29 people died.
McKevitt also received a six- year concurrent prison sentence for membership of an illegal organisation - the Real IRA.
On the third day of the appeal yesterday, Mr Birmingham said that FBI agent David Rupert, who infiltrated the Real IRA and who was the chief prosecution witness in McKevitt's trial, had performed the tasks he had agreed to do with "remarkable skill, resourcefulness and courage".
His courage and resourcefulness had served all the people of the State, counsel added.
Mr Birmingham said the decision to bring McKevitt to trial was unique in that it involved three states, with three different law enforcement agencies, each with a commitment to the rule of law. He said the DPP had gone to elaborate lengths to ensure McKevitt was given a fair trial.
He also said the disclosure of documents in that case "was without precedent in the history of this State". It had involved impressing upon the FBI and British security services the necessity for full disclosure to the defence of all relevant material.
McKevitt's lawyers have appealed against conviction on the grounds that there was not full and proper disclosure of all material relating to David Rupert and that the Special Criminal Court erred in law by not adequately assessing Mr Rupert's credibility as a witness.
The appeal is continuing.