The High Court decision that there was no inherent power to conduct such inquiries as that of the Abbeylara subcommittee (ASC) was wrong in principle and irreconcilable with previous Supreme Court decisions, the Chief Justice said.
He also saw no reason why politicians should not be able to participate in such committees with minds unclouded by pressures from their constituents or their political parties.
If there was inherent power in the Oireachtas to conduct such an inquiry as that of the ASC, there seemed no reason why the Oireachtas could not establish such an inquiry by legislation, provided that legislation allowed for the conduct of such inquiries in a strictly constitutional manner.
The only ground for questioning its constitutionality would be what was described as "structural bias" by Oireachtas members.
He found the that High Court was incorrect to describe the functions of the ASC as adjudicative.
The killing of a civilian by members of the Garda was a matter of immediate and legitimate public concern and an inquiry to ascertain the facts which resulted in the killing and to reach appropriate conclusions as to any legislative, regulatory or administrative measures that needed, in the committee's view, to be taken, was an entirely appropriate and proportionate response.
He agreed it was not reasonable for the ASC to defer the gardaí's right to cross-examine and upheld the High Court finding that this breached fair procedures. He also accepted there were errors in the drafting of orders and resolutions relating to the ASC's establishment but noted similar errors occurred in the conduct of legal proceedings.