Giving evidence at a public hearing on Tuesday, ACT association branch president Elizabeth Gallagher rejected a proposal from Greens Minister Shane Rattenbury for medical cannabis, describing it as "too ad hoc" and without strict enough regulation to be safe and effective.

Dr Gallagher said the scheme's proposal for doctors to provide permits to patients for growing their own medical cannabis plants would be problematic and open to misuse.

Last month the association called for more clinical research and for a national approach to cannabis being used for health outcomes. Dr Gallagher appeared at the hearing with AMA chief executive Christine Brill.

"We have a responsibility to patients to make sure that what we are prescribing for them [is something] that we understand," Dr Gallagher said.

"We would really like to be able to get a quality controlled, targeted product out, if we are going to use it – rather than just the crude [cannabis] product which is more like a sledge hammer."

The hearing was told that cannabis had been illegal and unregulated in Australia for more than 90 years and was currently the most widely used illicit drug in the community.

Dr Gallagher said widespread access meant the drug remained open to misuse and abuse and any regulation for a medical scheme in the ACT should be more strictly controlled than the current legislation.

Calling for an evidence-led debate, she said there was no anecdotal or documented levels of current unregulated use of cannabis by sufferers of medical conditions, including cancer, in the Canberra community.

"We start to lose the objectivity once we see pictures of little kids fitting, of this sort of story. It really takes away from what we really want, which is a scientific, evidence-based response to problems.

"It is very easy for people to talk anecdotally without proper information to back those sorts of statements up."

Mr Rattenbury's proposed scheme would allow terminally and chronically ill people to grow cannabis and use the drug as part of their treatment.

Released in draft form last year, it would see sufferers of terminal and chronic illness apply to the ACT Chief Health Officer for approval to possess and use cannabis. Patients using cannabis and oils, often illegally, report relief from pain and suffering, including nausea.

A medical scheme received support on Tuesday from advocates Families and Friends for Drug Law Reform and the Public Health Association of Australia, but was opposed by controversial lobby group Drug Free Australia.

Political campaign organisation, the Australian Christian Lobby, said it was not affiliated with Drug Free Australia, as was reported on Tuesday.

Managing director Lyle Shelton wrote to the Assembly's Health, Ageing, Community and Social Services Committee in February calling for scientific trials of cannabis for medicinal purposes, so it could be tested against the same standards as any other drug.

"If cannabis has a genuine palliative effect that other drugs cannot provide, it should be available to patients in the same way other medications are," Mr Shelton said.

"However, ACL is concerned by the proposal to decriminalise the possession, cultivation, and use of the cannabis plant, especially before a thorough trial has taken place."

Health risks from cannabis use raised by experts meant "a more cautious, scientific approach to developing medicinal cannabis treatments" was needed rather than decriminalisation, Mr Shelton said.

More public hearings are planned for next week. The committee's report is due by the end of June.