Newcastle Knights legend Andrew Johns has backed the Minns government's move to provide warnings to patients found driving with medicinal cannabis in their system.
The government will announce on Thursday that it will introduce legislation to change how the law treats medicinal cannabis patients who drive.
Under the reforms, drivers taking prescribed medicinal cannabis containing THC will no longer be automatically penalised.
They will receive two warnings and get the chance to adjust their dose and driving behaviour after medicine use.
Johns said the law change was "common sense".
"I've been taking medicinal cannabis for over six years now," Johns said.
"It's been a game-changer for seizures, inflammation and sleep. I take it around eight at night, I'm asleep by ten and I wake up the next morning clear-headed.
"If you use it responsibly there's no reason you shouldn't be able to drive."
About one million medicinal cannabis users have been approved in Australia, with more than 300,000 of these in NSW.
Premier Chris Minns said "this is a significant reform for NSW, but it's one we are approaching carefully".
"For thousands of people, medically prescribed cannabis is life-changing medication," Mr Minns said.
"Our current laws enable people to safely and legally drive, while taking a wide range of prescription medications."
Health Minister Ryan Park said "medicinal cannabis is allowing many people in our community to go about their daily lives".
"These reforms work to get a balance right between safety and legal use of medicinal cannabis," Mr Park said.
Dr Will Tregoning, chief executive of Unharm, said "patients tell us constantly about the toll of these outdated laws".
Dr Tregoning said this included lost jobs and "the impossible choice between their health and their licence".
"Reforming this law is also good for road safety," he said.
"In some cases, the current law has made roads less safe by forcing patients off medication that was helping them sleep."
Police Minister Yasmin Catley said "road safety remains the number one priority".
"These reforms do not change the ability of NSW Police to take dangerous drivers off our roads," Ms Catley said.
Minister for Roads Jenny Aitchison said the law change would ensure "people using medicinal cannabis on prescription can drive a vehicle where they are not under the influence".
"This change does not give anyone permission to drive a vehicle while affected by cannabis or any other drug," Ms Aitchison said.
Professor Iain McGregor, academic director of the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney, said "THC can be detected in the body for weeks after cannabis use".
"But our research shows impairment typically clears within hours and is often minimal in people taking cannabis for medical reasons," he said.
"We've also shown that THC concentrations in blood and saliva are poor and inconsistent indicators of impairment.
"Prosecuting patients on the basis of THC presence in saliva, long after any effect has worn off, is manifestly unjust."
Former magistrate David Heilpern said "I sentenced hundreds of defendants under this law as a NSW magistrate".
"They were not impaired. They were patients following their doctor's advice," he said.
Legalise Cannabis Party MP Jeremy Buckingham, who pushed for changes to the law, said "for many medicinal cannabis patients, the ability to drive is not a luxury".
"It is the difference between getting to work, caring for family, attending medical appointments and participating in everyday life," he said.
To be eligible for the new system, drivers will be required to enrol as a registered medicinal cannabis user with Transport for NSW.
They must provide proof of a valid prescription and complete an online education program about cannabis and driving safety.
The changes will only apply to NSW drivers on an unrestricted licence. They exclude L- or P-plate drivers and commercial drivers.
Under the laws, the government will introduce a three-strike approach for registered medicinal cannabis users.
This sought to recognise that some drivers may test positive to THC, despite using their medication lawfully and responsibly.
Under the new system, registered medicinal cannabis users will still be roadside drug tested.
If a driver returns a positive roadside test, they will continue to receive an immediate 24-hour driving ban while the sample is sent for lab testing.
If the lab result shows THC below the maximum threshold of 50 nanograms per millilitre in their saliva, there will be no charges or further action.
If the lab result shows THC at or above the threshold, the driver will receive a warning letter for a first or second detection within two years.
This will give drivers the chance to adjust their dose and driving behaviour after medicine use.
A third detection above the threshold within the two-year period will trigger a fine of $704 and a minimum three-month licence suspension.
If the driver has alcohol present, or the lab result shows multiple illicit drugs or any drug other than THC, the driver will face the standard drug-driving offence.
Registered users will continue to be subject to post-crash blood and urine testing following serious crashes, and will face serious charges if they are found to be driving while impaired.
Patients who are not registered will continue to be subject to the existing roadside drug driving laws.
