The executive director of the Irish Council for Civil Liberties (ICCL), Liam Herrick, has called on gardaí to clarify what is being done with information the force has retained on "completely innocent people".
Mr Herrick was speaking following allegations that An Garda Síochána has retained files on people cleared of producing or sharing sexual abuse material.
Mr Herrick told RTÉ Radio’s Morning Ireland that there were "potentially negative consequences" for the people involved, and asked if the information was shared with the Pulse system and other agencies.
It may also be the case that gardaí did not know they were retaining the information until the issue was flagged by ICCL, Mr Herrick said.
"Information about completely innocent people and completely innocent material is being retained by An Garda Síochána and they do not have a valid legal basis for retaining personal data in relation to that material.
"Does any further consequence flow from this? Is this information flagged on the Pulse system, is it accessed by other members of An Garda Síochána or other agencies? Is there potential negative consequences for some of these people?
"The answer to that question is we don't know," Mr Herrick said.
He explained the not-for-profit National Center for Missing and Exploited Children (NCMEC) in the US acts as a repository of child sexual abuse material, which receives information from internet providers and members of the public. The NCMEC then share it with law enforcement agencies around the world.
"Since 2010, An Garda Síochána have been receiving information from [NCMEC] and since 2015, they've been getting it directly from this national centre in the US.
"The guards then process that information and they filter out that which they believe is serious material which merits criminal prosecution and that which isn't."
"Last year, we wrote to An Garda Síochána to get more information about what they do with this data.
"We're part of the European digital rights network that is concerned there may be difficulties with how the system operates.
"Obviously everybody wants to take the strongest possible measures to deal with child sexual abuse material, but concerns have been raised that there might be false positives - material might be flagged as child sexual abuse material that's innocent and also what happens that material subsequently," Mr Herrick explained.
"In March 2021, we wrote to the guards and in October 2021 we got a detailed response from AGS (An Garda Síochána) which said that in the previous year over 4,000 referrals were made to AGS about potential child sexual abuse material.
"But 11 per cent of that information was categorised by AGS as completely innocent. There were various other categories, and at the end of the day only 10 per cent of the information they got was actually actionable for criminal processing, but of that 11 per cent that was innocent 471 cases, now a referral might have more than one person involved."
Mr Herrick added that it would seem that each referral does lead to "an entry on a database", however, he questioned what happens to that information afterwards.
"The difficulty is that it would seem from the correspondence we've had with An Garda Síochána that they retain that information.
"We've got confirmation that all of the referrals go on a database and nothing is removed from the database so far, so it is still retained."
Mr Herrick said this was a Europe-wide problem which raised a number of very serious questions.
He questioned whether the information is being retained illegally, and if so, it should be deleted.