Six men were cleared of being members of the Continuity IRA in Limerick and one man was convicted of the charge at the Special Criminal Court yesterday.
It was one of the longest trials in the history of the non-jury court.
The court was told that the men were arrested after a Garda surveillance operation on suspected dissident republicans in the Limerick area.
Armed detectives broke down the door of a house in the Shanabooley Road area of the city after following a number of men there at different times.
Chief Supt Gerard Kelly gave sworn evidence that he believed each of the seven accused was a member of an illegal organisation on December 17th, 2001. He said his belief was not based on the events of December 17th, or on anything found in the house.
Mr Justice Butler, presiding, said that in the case of six of the seven accused men "there must be a reasonable doubt that an IRA meeting was taking place. In light of their strong sworn denials of membership of the IRA we have a doubt, not about the veracity of the evidence of Chief Supt Kelly, but about the validity of his opinion based on confidential sources."
The six men were discharged and left the court to be greeted by up to 20 supporters, who had been demonstrating outside the Green Street courthouse.
The court convicted Patrick O'Shea (54), Sir Harry's Mall, Limerick, of the charge and he was remanded in custody for sentencing today. Mr Justice Butler said the court found O'Shea's evidence "incredible".
The seven men had denied the charge that on December 17th, 2001, within the State, they were members of an unlawful organisation styling itself the Irish Republican Army.
The six men acquitted are: Mr Des Long (62), vice-president of Republican Sinn Féin, Shannon Banks, Limerick; Mr Patrick Kenneally (59), Crusheen, Co Clare; Mr Gerard Brommell (43), Rostura Crescent, Woodview Park, Limerick; Mr Robert McNamara (59), St Michael's Avenue, Tipperary; Mr Joseph Lynch (62), Beechgrove Avenue, Ballinacurra Weston, Limerick; and Mr Christopher Dunne (28), Donnellan Buildings, Rosbrien, Limerick.
The cost of the trial, which lasted 48 days, is estimated to run to over €3 million.
Twenty-seven gardaí, many of them armed, raided the house in Shanabooley Road where they suspected a Continuity IRA meeting was taking place and there were firearms present.
Three of the accused, Brommell, Dunne and Lynch, were arrested after they were seen running out the back door.
Mr Justice Butler said: "It transpired that no firearms were found on the premises."
The accused men said they had been attending an informal meeting of Republican Sinn Féin to discuss the setting up of a new cumann in the Munster area and the selling of calendars and newspapers for the organisation, as well as a forthcoming Seán South commemoration.