The Disclosures Tribunal has strongly criticised Tusla, the child and family agency, for its handling of the false rape claim made against Sergeant Maurice McCabe.
Mr Justice Peter Charleton said the agency gave the allegation an afterlife due to "astounding inefficiency and inertia".
He also concluded the file had been "filleted" by an unidentifiable person in the organisation and that from 2016, no one within Tusla considered owning up to the serious mistakes that had been made.
The report finds that the the rape allegation was "conjured out of nowhere" within a HSE counselling service.
He says this was a coincidence even if it seemed unlikely and all the witnesses from the HSE were honest.
Sgt McCabe was accused of a sexual assault by the daughter of a colleague in 2006.
This was dismissed by the Director of Public Prosecutions as not constituting a crime.
The tribunal heard that when the woman later went to HSE counselling in 2013, the assault was incorrectly inflated to a rape allegation by a template error.
Mr Charleton says the computer analysis bore this out.
The report also criticises the garda handling of the allegation saying the Northern Region never sent a corrected version of the allegation to Garda Headquarters.
Mr Charleton also says that while others were informed and incorrectly informed, Sgt McCabe was never contacted and told the mistakes had been made.
Tusla has accepted that child safeguarding practice and governance in the organisation's response to unfounded child abuse allegations against Sgt McCabe were "exceptionally poor and ….fell below the standards" that it expects of itself.
Judge Charleton said the tribunal may have been avoided had Tusla set out fully the mistakes it had made when dealing with the false allegations against Sgt McCabe.
In a statement this evening, Tusla reiterated its earlier sincere apologies to Sgt McCabe and each member of his family for the impact the agency's errors had on them.
It added it was sincerely sorry that its standards did not meet those which could be reasonably expected by Sgt McCabe and his family. It added that it wished to apologise to others who were also affected by its errors.
The agency said a HR process has been commenced around the management of the case, and "it is expected that this process will be completed in due course".