The commission also looked at the Sophie Toscan Du Plantier case
An investigation into the mass recording of telephone calls in garda stations has found the practice was not lawful.
But it says no criminal cases were significantly affected by the practice.
The Fennelly Commission found that it is "reasonable to conclude, based on the evidence before it, that no widespread or systematic, indeed probably no significant, misuse of information derived from non-999 recordings took place".
The commission, headed by Mr Justice Nial Fennelly, was set up in 2014 to investigate telephone recording systems to record calls other than those to 999.
The commission was examining material from a large number of garda stations over several years.
It also looked at the specific implications of taping related to the garda investigation into the death of Sophie Toscan Du Plantier in Cork in December 1996.
The report says continuing the recording of calls should now be put into legislation.
The Attorney-General has also come in for criticism for the level of alarm to the issue when it was uncovered in 2014.
In a statement, the Government says the report reinforces its decision to undertake a root and branch review of gardaí.
However the commission found no evidence of knowledge of the recording of calls on the part of relevant Justice Ministers, the Department of Justice, the Office of the Attorney-General, the Chief State Solicitor, GSOC, the Data Protection Commissioner or the Director of Public Prosecutions (DPP).
The Government says many findings are still "of great concern" - including in relation to the unlawful nature of the recordings, lack of effective oversight and procedures, and in relation to the content of certain telephone recordings relating to the investigation of the death of Ms du Plantier.
"These findings clearly explain why it was necessary to establish the Commission of Investigation in 2014", the Government says.
The Cabinet granted an extension to the inquiry to complete its work in November 2015, after the commission expressed concern at the sheer volume of work in relation to the tapes.
While a previous interim report, released in September, vindicated the Taoiseach Enda Kenny of any wrong-doing over the resignation of former Garda Commissioner Martin Callinan.
This was after a representative from the Department of Justice was sent to Mr Callinan's house the night before he resigned.