The tragic death of John Carthy was a matter which, in the public interest, merited proper and formal investigation, Mr Justice Hardiman said.
The Carthy family and gardaí had both expressed a preference for a tribunal of inquiry wholly independent of the political process.
The Abbeylara subcommittee (ASC) was conducted by seven politicians and claimed the power to make findings of fact, including findings adverse to a person and capable of impugning their good name.
There was no inherent power to carry out such an inquiry, which was without historical precedent in the 80 years of Irish independence.
This was not a case which attacked the work of Oireachtas committees. Nor was it an attack on parliamentary democracy.
It was a challenge to a novel assertion of a power to hold individual citizens directly accountable to a parliamentary committee.
What was proposed was to expressly consider the fatal shooting and that consideration, it was claimed, may lead to a finding of unlawful killing.
The alleged technical status of such a finding would not help a person against whom the finding was made. Many persons had been economically ruined and socially outcast because of such "legally sterile" decisions.
A person who sat in judgment on another must act in a quasi judicial fashion, avoid bias and the appearance of bias.
Some members of the ASC had given media interviews about its subject while the committee continued its work.