A proposal to allow the use of medical marijuana in the ACT would be a "large drain" on the health directorate's resources, according to the Territory's top doctor.

Greens MLA Shane Rattenbury has proposed legislation to make cannabis available to terminally ill patients or those suffering chronic pain, and a Legislative Assembly Committee is now canvassing public opinion at a public hearing on the laws.

Acting chief health officer Andrew Pengilley told the committee that under the proposed bill, the Health Directorate would have to approve each individual patient's use of medical marijuana.

"There will be a significant resource impost in running the scheme that we're talking about here: a register, and processing all these applications," he said.

"In an environment where we have a lot of other public health issues we want to direct resources to, this is going to be a large drain on those marginal resources."

Dr Pengilley said he supported the compassionate intent behind the bill.

But he said there were not currently enough safeguards to ensure doctors could be sure the product they were recommending was fit for use.

"Because the street supply is aimed towards recreational use, it's a very high THC [tetrahydrocannabinol] product with a high psychotropic effect," he said.

"If you look at areas that have prescription supply such as the Netherlands, they have actually controlled the THC component of what's available."

Dr Pengilley said the role of doctors in the proposal also needed clearer definition.

"If you look at say California, or places that have had a situation where there's been a medical endorsement but not prescription ... which has then been supplied by growers co-ops supplying them, then there's been fairly clear evidence of an increased entrepreneurship, if you like, and availability of products to fill markets," he said.

"It's difficult for absolutely everybody in the medical profession to fulfil the gatekeeper role at preventing that, either becoming an increased supply of people who do not necessarily have watertight evidence of clinical need or diversion into the illicit supply.

"This is proposing ... legal relief for the compassionate use of illicitly obtained cannabis, which is not something I particularly object to, but the involvement of the medical profession is in fact a secondary concern or a secondary way to make that look like a prescription of a normal pharmaceutical."

Notes on drivers licence suggested by chief police officer

The ACT's chief police officer Rudi Lammers also appeared before the hearing.

He said extra safeguards would be needed to prevent people taking medical marijuana from getting get behind the wheel of a car.

Assistant Commissioner Lammers said a potential way to monitor the use of medical marijuana and ensure road safety was to have notes added to an individual's drivers licence.

"When the cannabis was prescribed, for what use and what period of time, and whether or not there was a view from the medical practitioner that there was some advice given to the patient as to whether he or she should be even driving a vehicle," he said.

"There are lots of things that go into this."

Echoing Dr Pengilley's concerns, the Assistant Commissioner Lammers said strict regulations on the production of medical cannabis would need to be enforced to ensure it was safer than the illicit version of the drug.

"The consistency in quality of the drug produced through a number of different manufacturers has to be well considered," he said.

"So that you know that if you're getting it from two or three different pharmacies under the same prescription, that each and every time you're getting exactly the same drug.

"There is no way of regulating that if it is grown in a backyard.

"The only way you can really do that is if it's grown under strict supervision and controls, and then produced in a way where the potency can be controlled."

'Strict control needed on what pharmacies can dispense'

Assistant Commissioner Lammers said regulations would also need to extend beyond the growing of marijuana.

"There needs to be strict controls around where it's grown, how it's grown, where it's contained, how it's shipped, in terms of quantity harvested, quantity produced," said Assistant Commissioner Lammers.

"Then there needs to be strict controls around its transport to whomever is going to be the person who further refines, packages it up for sale, puts warning labels on.

"Then transit and passage from that particular place to a pharmacy for on sale, and there needs to be strict controls around what pharmacies can dispense and for what purpose, and what particular purposes it can be prescribed."

Of particular concern was who could administer cannabis for medical purposes, according to Assistant Commissioner Lammers.

He said it would be unreasonable for children with terminal illnesses to administer the drug themselves, but control measures would be needed for those who stepped in.