However, the agency said decriminalisation alone would not solve the drugs crisis and investment was needed in harm reduction, detoxification, rehabilitation, and supported accommodation.
The intervention comes on the final day of the Department of Health’s public consultation in relation to decriminalising drugs.
The consultation is feeding into the work of a high-level State expert committee, tasked with examining alternatives to the current criminal laws around drug possession for personal use.
In a statement, Merchants Quay Ireland chief executive Tony Geoghegan said the legal situation was failing those in addiction and a pragmatic, health-led response was needed.
“Decades of criminalisation have pushed people with serious addiction issues into the margins of society, acting as a barrier to treatment,” he said.
Mr Geogeghan said that Ireland had a “profound drug crisis” and that a different response, based on evidence, was required.
“A move away from criminal penalties for personal possession of illegal drugs can be one part of that. People in addiction should be receiving treatment, not a prison sentence.”
However, he warned that decriminalisation “on its own” would not solve the problem.
“The Government will need to step up to the plate by increasing investment in harm reduction measures, detox and rehabilitation programmes, and supported accommodation for people coming out of treatment,” he said.
“Only then will we have a truly health-led response to addiction.”
The statement comes just a week after a former senior Garda chief also backed calls for the decriminalisation of drugs.
Furthermore, former assistant commissioner Jack Nolan said a debate should commence on the legalisation of drugs.
In a rare public comment by a former senior garda on the sensitive issue, Mr Nolan had told Hot Press that while the Misuse of Drugs Act 1977 had many successes it was “time now to look at different options”.
The Department of Health public consultation was extended by two weeks, from the end of June to yesterday, after the department received over 14,000 responses to its questionnaire.
The State expert group is being chaired by Judge Garret Sheehan and comprises 14 other members, 11 from a government department or State bodies.
There are four officials from the Department of Health, two from the Department of Justice along with Detective Supt Brian Woods of the Drugs and Organised Crime Bureau, Dr Eamon Keenan of the HSE, and Dr Jean Long of the Health Research Board.
The DPP and the Probation Service also have a representative and there are two former drug users, and law expert Tom O’Malley.