The Irish Penal Reform Trust is warning that convicted sex offenders could go into hiding to avoid garda monitoring if their backgrounds are revealed under a proposed new law.
IPRT Executive Director Liam Herrick was responding to proposed legislation similar to "Sarah's Law" in the UK.
The proposed law would allow gardaí provide "relevant and appropriate" information on sex offenders to parents, schools and clubs responsible for children and vulnerable adults.
Mr Herrick said that legislation in the US, which identified the location of sex offenders, had led some offenders to deliberately avoid and evade scrutiny.
Roscommon-South Leitrim TD Denis Naughten has proposed the Child Sex Offenders (Information and Monitoring) Bill, which is similar to Sarah's Law.
That law is named after eight-year-old Sarah Payne, who was abducted and murdered in 2000 by a sex offender.
Speaking on RTÉ's Today with Sean O'Rourke, Mr Herrick said that there was "very scant evidence" that the Sarah's Law system in the UK had provided any positive impact.
He said that evaluations carried out into the Sarah's Law provisions were inadequate.
Mr Herrick said gardaí currently have the power to contact schools if there is a perceived risk from a sex offender in the community.
He said if there was "nothing to be gained" from introducing this legislation then it would end up taking resources away from other vital areas, such as improving the speed with which gardaí carry out vetting of individuals.
Mr Herrick said there was also a concern that releasing information such as this to the public could lead to an increase in vigilante attacks.