Today’s High Court judgment on the Oireachtas sub-committee into the shooting dead of Mr John Carthy in Abbeylara decision will be challenged in the Supreme Court, Fine Gael TD Mr Alan Shatter, said.
Speaking after the ruling, which upheld a challenge by 36 gardai to the sub-committee of which Mr Shatter is a member, he said if the Supreme Court upheld the High Court decision, the matter would have to go to referendum.
"My personal view is that this is a matter that will have to be addressed by way ultimately by a referendum," he told RTÉradio.
He also said the ruling meant the DIRT inquiry that ended in October 1999 and the ongoing rail signalling inquiry could be considered unlawful.
Spokesman for the Garda Representative Association Mr P J Stone said the judgment had vindicated the gardai and backed calls for a judicial inquiry for the sake of both his members and the Carthy family.
He said: "It is a fact that this has been dragged on for so long by politicians, who should in the first instance not be putting their noses into it anyway.
"I hope that rather than wasting time going to the Supreme Court, the Government will now set up an inquiry so the matter can be dealt with satisfactorily."
After today's court ruling the dead man's sister, Ms Marie Carthy, said she was "not surprised, but very disappointed" at the decision.
She added: "It does not make sense, we were happy with the work this committee was doing. It had raised an awful lot of important questions that needed to be answered - and still need to be answered, and we would like to thank them for the work they have done."
Ms Carthy called on the Government to launch a full public inquiry into the shooting "sooner, rather than later, so that all of these questions can be answered".
Additional reporting PA