The government has plans underway to establish a medical cannabis scheme in the ACT and allow residents safe and legal access to cannabis products as soon as practicable.

The decision followed a reclassification of cannabis by the Therapeutic Goods Administration from prohibited to controlled substance, and the passing of laws by the federal government to allow legal cultivation of the drug.

But the ACT's existing drug-driving laws do not exempt people who use cannabis for medical purposes, and also do not account for level of impairment.

Roadside drug testing can also pick up marijuana in the system sometimes days after use, while a positive result means a driver could lose their licence and face fines.

Meanwhile, ACT police are taking a hard line on drug driving and catching a record number of people. Last year, between December 23 to January 2, police said 28 out of the 88 drivers who were tested for drugs returned positive results, pending further analysis.

"Drug driving is downright dangerous, not just to the driver but to everyone on the road around them. It's disappointing for police that these drivers aren't getting the message or taking responsibility," acting officer in charge of traffic Sergeant Ken Hedges said.

The ACT's zero-tolerance approach has come under fire from civil libertarians and criminal defence lawyers, who have expressed significant concerns about how a medicinal cannabis scheme would co-exist with current laws.

Solicitor Adrian McKenna, of Ben Aulich and Associates, said it would be "nonsense to reform one without the other" and said ACT penalties for drivers caught with cannabis in their system, even if it was a "minuscule" amount, were the country's harshest.

He said drivers tested even weeks after consuming cannabis could face a criminal conviction and six months to three years licence disqualification for a first offence.

"This is likely no matter the concentration, or if their job depends on their licence," Mr McKenna said. "Any changes to medicinal cannabis laws really should make some allowance for users to drive if the concentration of cannabis is sufficiently small and has no discernible impact on their driving."

Such a shift would bring the territory's drug-driving laws into line with drink driving legislation, which allowed drivers and riders a blood alcohol concentration up to 0.05.

Lawyer Jacob Robertson, of Sharman Robertson, said medicinal cannabis users who had to drive risked an on-the-spot, 12-hour driving ban if they were stopped by police and suspected of taking drugs.

"It would open a can of worms, should those who qualify to consume medicinal cannabis still have a valid licence or be able to drive even after 12 hours of consumption, as they will almost certainly have cannabis in their system," he said.

Paul Edmonds, of Canberra Criminal Lawyers, said an exemption might need to apply to drivers signed up to the scheme, similar to a defence for special drivers who took medication which contained alcohol.

The dilemma was raised in NSW last year when a man who used marijuana for medical purposes was caught up in drug driving laws. A judge found him guilty, but accepted evidence the man used cannabis for pain relief and had done so four days before driving.

The judge commented on how cannabis remained in the system for some time, but the legislation did not account for impairment. NSW government guidelines suggest it is "typically" safe to drive 12 hours after using marijuana without being picked up by mobile testing.

The view of medical cannabis advocacy group the Canberra Med Shed was that the drug should be considered alongside other prescription medication; users should self-monitor for impairment, and police should patrol for dangerous or impaired driving.

The government said it was working to review the implications of medical cannabis scheme. ACT Health has called for interested and qualified people to join the Medical Cannabis Advisory Group.

A separate committee will be established later in 2017, to review the legal implications. This would include how people using medical cannabis would be affected by traffic laws, as well as the need to maintain road safety.