A DISSIDENT REPUBLICAN has failed in his efforts to have a criminal conviction for membership of the Real IRA overturned on the basis that evidence used to convict him was illegally obtained.

The Court of Criminal Appeal rejected the challenge by Michael McKevitt, who argued that evidence corroborating accounts given by a witnesses against him was obtained under a search warrant that would subsequently be found unconstitutional.

McKevitt, 63, was convicted at the Special Criminal Court in 2003 for membership of an illegal organisation Real IRA and directing terrorism between dates in 1999 and 2000. The prosecution case relied on an FBI informant, David Rupert, who had infiltrated the illegal organisation.

In that case, Rupert had given evidence saying he had installed a computer in McKevitt’s house, and had seen certain items in the house when doing so – evidence corroborated by a search carried out when Gardaí searched his house. This undermined McKevitt’s claim that the two had never met.

However, the law under which the warrant for that search was obtained – Section 29 of the Offences Against the State Act 1939 – was struck down in 2011, when the Supreme Court said it was unconstitutional to allow Garda superintendents to issue search warrants in investigations that they were themselves involved in.

The Louth man therefore argued that this was a “newly discovered fact” which undermined his original conviction – but today the Court of Criminal Appeal said it could not find that the conviction had been made “unsafe and unsatisfactory”.

It said the Supreme Court had previously ruled that the unconstitutionality of a search warrant could not be used to cast doubts over cases that had previously been completed in courts – particularly where those cases were nearly ten years old.

In those cases, the court ruled today, the State and prosecution had acted in good faith and in accordance with what was considered lawful at the time.

McKevitt has previously lost separate appeals claiming that Rupert’s testimony was unreliable because he had been paid by the FBI and MI5 for his role as an informant, being defeated at the Supreme Court in his efforts to claim that Rupert was not a credible witness.

In June 2009 he was one of four men who was found to be liable for the 1998 Omagh bombing in a civil case taken by the families of the 29 victims.

His original criminal trial in 2003, over membership of the Real IRA, heard evidence that he had planned to attempt the assassination of then-British prime minister Tony Blair.