Mr Justice Barr is to head the tribunal of inquiry into the fatal shooting by Garda marksmen of Mr John Carthy in Abbeylara, Co Longford, two years ago.
The Minister for Justice last night named him as the sole member of the tribunal, set up to establish the facts and circumstances of the killing.
Civil liberties campaigners said the inquiry was long overdue and called for it to be held in Longford.
Mr Carthy was shot by the Garda Emergency Response Unit after a two day stand-off outside his home in April 2002. An attempt by TDs to investigate his death was stymied when gardaí successfully pleaded before the High Court that the inquiry went beyond the remit of the Oireachtas.
The new tribunal has been ordered to report to the Clerk of the Dáil within four months of its establishment.
Last night the Irish Council of Civil Liberties (ICCL) commended the Minister for Justice, Mr McDowell, for appointing Justice Barr so early into his term. The acting director of the ICCL, Mr Liam Herrick, said Mr Carthy's family had already been made wait too long to learn the truth about his death.
He said: "There was no legal reason preventing the previous Government from establishing this tribunal before now, and the ICCL has always insisted that the circumstances of John Carthy's death at the hands of the Garda Emergency Response Unit can only now be properly investigated by a tribunal with full judicial powers.
"A judicial tribunal of inquiry is the only appropriate way to vindicate the rights of all the parties involved, including the gardaí."