A range of allegations being investigated privately by the Mahon tribunal may not now proceed to public hearings following a decision of the Supreme Court yesterday, according to a number of legal sources.
As a consequence, the work of the tribunal is expected to conclude a number of years earlier than had been anticipated, the sources said.
In April 2005, the tribunal drafted a confidential list of allegations or matters it "may decide to continue its inquiries and/or proceed to public hearing in respect of".
The decision of the Supreme Court yesterday has thrown into doubt the tribunal's right to investigate any of the matters listed, according to the sources.
The allegations listed by the tribunal have not been made public but one source yesterday said they include up to 47 "matters".
The Irish Times is aware that last year the Taoiseach Bertie Ahern was informed that the tribunal had decided it would be holding public hearings in the future into tax designation decisions made under the terms of the Urban Renewal Act. The tribunal has not stated this publicly.
The tribunal told Mr Ahern about the intended hearings in the context of its inquiries into his personal finances though it did not say it would be calling him as a witness in any such hearings or that any allegation had been made against him. Mr Ahern was minister for finance during part of the period during which urban renewal designations were made.
In December 2004, the Oireachtas amended the tribunal's terms of reference and instructed it to record in writing all the matters it intended holding public hearings into in the future and about which a public announcement had not already been made.
This amendment to the tribunal's terms of reference was designed to limit the future work of the tribunal at a time when it was feared it might still be sitting in 2015.
However the Supreme Court has now ruled that the tribunal's response to the Oireachtas was drafted in such a way that it did not comply with its amended terms of reference.
The ruling was made in an appeal by the Fitzwilton group against a public inquiry being held by the tribunal into a £30,000 payment to the former communications minister, Ray Burke, in 1989, by the Fitzwilton subsidiary, Rennicks Ltd, which Fitzwilton maintained was for Fianna Fáil.
The tribunal was set to examine whether the payment was linked to an MMDS or television transmission system being developed at the time by Independent News and Media and two international partners. Both the Independent group and the Fitzwilton group are strongly associated with Sir Anthony O'Reilly.
The list drawn up by the tribunal in April 2005 in response to its amended terms of reference included an item described as "Fitzwilton-MMDS-Payment to Ray Burke by Rennicks".
The Supreme Court yesterday ruled the tribunal's response to its amended terms of reference failed to comply with those terms. "Consequently the tribunal has no jurisdiction to proceed with the £30,000 Fitzwilton module."
A spokesman for Fitzwilton said it was pleased with the court's decision. "We had always believed that the tribunal had failed to comply with its terms of reference. This was a critical issue of law that required clarification."
In her ruling yesterday Ms Justice Susan Denham also commented on the fact that the tribunal was established in 1997.
"The concept behind the establishment of a tribunal is that there be an inquiry into definite matters as a matter of urgent public importance," she said. "The fact that the tribunal is still inquiring 10 years later is the antithesis of an urgent public inquiry."