Parliament Rejects Bill That Would End Driving Discrimination; Latham Jeers ‘Pass The Bong’

Read time: 2 minutes

Discrimination starts at the top.

Last week, the Road Transport Amendment (Medicinal Cannabis – Exemptions from Offences) Bill 2021, was voted down by the Liberal-National and Labor parties.

Those in favour of drug driving law reform were defeated in a 29-6 vote.

This Bill was introduced by Greens MP and drug law reform campaigner Cate Faehrmann last year, the Amendment would have provided patients who have been legally prescribed medicinal cannabis with a medical defence against drug-driving charges if they were unimpaired. 

Prior to last night’s debate, Drive Change wrote to all Members of the Law and Justice Committee, highlighting that medicinal cannabis remains as the only prescribed medicine that does not have a legal defence for driving.

Pass the bong.


There is no evidence that our current Roadside Drug Testing have made roads safer and crash risk estimates for cannabis are lower than crash risk estimates for a number of commonly prescribed drugs including benzodiazepines.

At the end of the vote, a snide comment was passed by one of the Members (the Hon. Mark Latham MLC) to “pass the bong,” with the Road Ministers laughing at this remark. This childish antic is one in a string of out-of-line

Since losing his campaign for Prime Minister in 2004, Mark Latham has become somewhat infamous for his crass comments and outward disrespect toward several communities.

Such appalling behaviour should be called out. There have been over 250,000 approvals for medicinal cannabis in Australia, and this sort of language is disrespectful to the thousands of patients with lawful approvals. Australians who have been approved for medicinal cannabis, but particularly to patients who have had their license taken away, lost their job, their livelihood, and quality of life due to these drug driving laws. 

In reducing the stigma around (medicinal) cannabis, it is important that we curb the use of insensitive language.

Such language and remarks from Mark Latham highlights the stigma, discrimination and criminalisation around this medicine. 

In order to change this, we need to remember to make sure Australians who are treated with medicinal cannabis are spoken of respectfully. There needs to be a shift in our perceptions, a change in how we speak, and most importantly, we need the laws to change. With the most recent Parliamentary defeat, the law remains discriminatory against these patients.

You can view the debate below: 

Share your story and write a letter to the Chair of the Law and Justice Standing Committee (the Hon. Christopher Rath)

Medicinal Cannabis and Australian drug driving laws in practice

Read time: 10 minutes

Lawyer Mat Henderson shares his reflections on possible ways around the drug driving law impasse and his experience defending a professional driver (and die-hard Storm fan) who was penalised for medicinal cannabis.

“It’s the attainment of justice and fairness that gives lawyers their buzz.”

So said The Hon Michael Kirby during one of the dozen visits to UTS Law School during the 00’s. The truth is, there is little to no buzz for a lawyer doing pro-bono work for medicinal cannabis cases. After five years of this sort of work, I can attest to that. What it really is is a grind of hearing heartbreaking patient stories and organising of doctors’ letters, which all feels more like shoveling sand against the tide than it does practicing law.

The lack of buzz stems from an inability to “change the law” in the time-honoured way by approaching courts, arguing the distinguishing facts of your case, setting a precedent, and changing the law (a gross over-simplification).

It doesn’t matter if “Granny Scroggins” is a cancer patient who last consumed her prescribed THC a month ago but then stopped being able to afford it. If it is detected in a roadside oral fluid drug test, she’s breaking the law. These laws seems to suggest that presence is presence and criminality is criminality. Even if you never thought of yourself as a criminal, as Granny Scroggins never did. If THC is detected in your system, you are.

In every Australian jurisdiction (bar Tasmania), it remains illegal to operate a motor vehicle with any detectable level of THC in your oral fluids.

Don’t even sit in the driver’s seat of stationary car if you had your THC-containing medicine today. It’s a zero tolerance approach to any presence of THC. This law persists, despite the increasing number of international jurisdictions which are adopting a per se approach, i.e picking a measurement of THC-in-blood and only making it a criminal offence to drive if that level is detected.

Whether it’s Granny Scroggins or your cousin Cody, the unjust drug driving laws can have serious consequences for medicinal cannabis patients.

The basis of our road laws are inherently flawed

A zero tolerance approach focused on saliva testing is fraught with accuracy issues. The current police practices take your saliva sample and sends it off to a lab. There, it winds up in a whizz-bang machine that looks for evidence of THC in your fluid, regardless of how long ago it was consumed. THC consumed days or even months ago can show up through this method. Whether it reads a faint positive or false positive, the law doesn’t care. What this machine spits out is essentially the live or die results of your driving priveleges.

Read more: THC in Blood and Saliva Not Indicative of Impairment, Studies Say

Australians don’t want unruly and impaired recreational consumers of THC on our roads.

Nor do we want people impaired by their lawful THC meds to get behind the wheel when they bloody well should not.

These are a given.

Australians also trust each other to be responsible when it comes to taking any prescribed impairing medicine (as directed) and to not operate cars, mix the medicine with booze or use heavy machinery if they feel impaired.

Common sense dictates that most folk apply the ‘next day rule’ to impairing drugs. This should also be a given when it comes to medicinal cannabis but law makers appear to be blocked by law enforcers. This is not how the separation of powers is meant to work.

How Parliament is Working to Change the Law

If you got this far, you may or may not know about the Parliamentary developments in Victoria and NSW.

For those who need to be caught up, the decision was: “More research required.”

Over the last ninety years, police have professed to be experts in determining whether or not a person is affected by cannabis/THC. Now we’re essentially told that such rudimentary policing skills are beyond them and that whiz-bang machines are more reliable.

Righto then. Below is my personal account of what will likely continue to happen whilst the research progresses.

Mat Henderson’s Tricky Tale of Defending a Medicinal Cannabis Patient

Two years ago, I took a call from a friend who works in the locally-licensed medicinal cannabis space.

A doctor had just called them about a patient on a 50:50 product who consumed 0.25 of a ml of oil (approx. 2.5mg CBD and THC) at 8am and then got pinged by a roadside drug test at 4pm. The patient is a professional driver with a bad spinal injury and felt no adverse impairment that day at any time during the day of offending.

His name is Will, “he’s a Storm fan and he’ll make sure you’re aware of it.”

More about Will later though. First Let me firstly give you a flavour of the factors you need to weigh up when working with a person about their history of prescribed THC, traffic history, and logistics around the day of offending.

Any reasonable person would be able to understand there was no impairment from medication on Will’s part. But that doesn’t matter; what matters is how the law is written.

Read more: Answering Cannabis Law FAQ

The way the laws are currently written, unless you have a reasonable explanation for how the THC got into your saliva passively (and possibly without your knowledge), a court is in no position to do anything other than apply the law and mark your actions as criminal.

Detection of any amount of THC results in the minimum penalty 3-6 months loss of license.

If you’re given a fine and purport to contest it on any grounds other than passive/unknowing ingestion of THC, you’ll find yourself in a legal cul-de-sac without a defence that a court is able to spend any time listening to. Best you don’t go speculating on how reasonable your reasonable explanation is without seeking formal legal advice. This blog post is not that.* 

When I do offer legal counsel to clients, I commonly hear the same story:

“I am a lawful medicinal cannabis patient”

“I take my medicine lawfully.”

“I’m not some scallywag kid driving when stoned.”

Sadly, none of these remarks are a good defence as the law remains as it is. Having detectable levels of THC in your saliva is a punishable offense, and patients ought to think twice about blurting out this knowledge after returning a positive roadside THC test.

If you know how the THC got there (and it was from consumption of your prescribed medicine), please don’t expect the police to use that information to apply leniency and wave you on.

However, if you’ve thoroughly educated yourself on the futility of arguing a medicinal defence and understand that if you contest the fine, you’ll inevitably end up pleading guilty, then you may wish to seek leniency in sentencing. If so, keeping your story consistent in any dealings with the police and the courts is always wise.

Always consult your doctor if you return a roadside THC positive.

Ask nicely and your doctor should write a supportive letter to the court outlining what conditions you’re diagnosed with, what medications you’re on and their brief opinion as to the efficacy of those medicines and any overall symptom relief and improvement in your quality of life.**

With such harsh and unjust laws, what could any leniency look like?

Well, perhaps you may not have conviction recorded or face an unsettlingly large fine.

Like I mentioned at the start, there’s no justice buzz for lawyers here. Not when every THC detection matter feels like nailing jelly to the ceiling, fighting a retreat with the British at Dunkirk or fighting against them at Ruapekapeka, massively outgunned but most certainly not out-witted. On most facts, a scrappy draw is the best result you can ask for.

The preservation of a future career working on the Canadian ski fields is a lifeline for some people. A criminal conviction in Australia tips poutine all over plans like that. However, if a person has to revert to previous medications like opioids and benzodiazepines which may well kill them in order to avoid offending in the future, then it’s hard to interpret that as anything other than a loss.

Losing all the time sucks.

It’s rough terrain for medicinal cannabis patients and lawyers looking for a win against the current drug driving laws.

Despite knowing this, I still wanted to speak to Will…

This was back during the first lockdowns of the pandemic and there was a strong public interest in ensuring food supply networks remained functional. Lawyers chasing the fairness buzz, like good reporters, are always looking for good facts. Surely such facts warranted a letter being sent to the prosecution to seek withdrawal of charges that Will was facing on public interest grounds.

Either way, after a long chat with Will, it was clear he had a unique factual matrix worth exploring and even if there was no joy to ultimately be had in court, there was the prospect that the case may have communal learnings for all in the drug law reform space.

Coincidentally, it was also around this time that Drive Change was founded, and David Heilpern was roped in to consult pro-bono. Greg Barns SC was instructed to appear and graciously agreed to do so pro-bono as well.

This is where things start getting lawyer-ly

Everything about Will’s circumstances warranted a request for some prosecutorial discretion. Through endless lockdowns, delays, illnesses, and adjournments, this approach was initially taken twice. First with the police prosecutors at the Magistrate’s Court. They stated the prosecution would proceed. Secondly with the top Victorian prosecutor at the Office of Public Prosecution where, in April of this year, they also stated that the prosecution would proceed.

Excerpts from those reps drafted by me and settled with David and Greg below.

On 11 August, Greg appeared for Will at Heidelberg Magistrate’s Court. In the absence of a defence as to how the THC got into his system, Will pleaded guilty.

In being deferential to the presiding judicial officer, we shan’t regurgitate their words verbatim, less to say that the court was moved by Will’s supporting letter from his doctor and his attempts to have a more functional life beyond opioids. There was no fine payable and no conviction recorded but the court was compelled by law to suspend Will from driving for 6 months. Will was given the lowest possible penalty just as Greg wrote submission that Will is “ultimately a victim of the Victorian legislature’s failure to keep abreast of the development of medicinal cannabis as a legitimate form of pain relief.”

Will has had some time to plan around the inevitability of a license suspension but still, it’s hard. He tells me a McDonald’s has opened in walking distance from his new place. He can bang out some hours there to keep some funds coming in.

He shouldn’t have to work at Maccas for 6 months because of being a lawful medicinal cannabis patient who drove whilst unimpaired. Yet with detectable levels of THC in his saliva, that’s what he’s faced with. All medicinal cannabis users ought to be afforded the right to drive provided they aren’t impaired by THC (to Maccas even).

The best approach to testing for THC

Due to the vagaries of THC and human metabolism, it’s not looking mega-likely that sampling your saliva or blood and reverse calculating the timeframe in which you *may have* last consumed THC is going to be possible anytime soon.

Sure, there’s cannabis breathalysers in the R&D pipeline but thus far they are capable of detecting smoked and vaporised cannabis, not orally or sublingually ingested THC.

Suppositories? Forget about it. Even if there was a device on the market that purported to test for ingestion of cannabis via anal suppository, I imagine that both the police unions and civil libertarians would unite to oppose its use.

Basically it seems as if The Man is unwilling to budge on the issue of THC detection until such time as someone in a white coat provides them with the equivalent of “0.05 on the Willie Nelson Dial” (as they see it) and the means to conduct the test within in a roadside mouth-swab oriented environment.

Read more: How Other Countries Have successfully ImpleHow Other Countries Successfully Updated Drug Driving Laws for Medicinal Cannabis Patients (and How Australia Can Catch Up)mented Drug Driving Laws


The law, in my humble opinion, as it stands in this area, is an ass.

We have a set of laws on our statute books that unfairly target a growing swathe of the population with the unnecessary stain of criminality. This is an unsatisfactory state of affairs. Given the outcomes of the recent Parliamentary reviews referred to above, it is a status quo that will continue for however long it takes for the research to be done, then peer reviewed and published.

Q. How long will that take?

A. Probably five years and as Bowie sang in Five Years, my brain hurts a lot.

I wish this article contained a happier call-to-action beyond sit down, shut up and wait for the scientists to finish whatever it is they do behind their velvet curtain.

Where to from here?

When the callout comes for trial participants, best we spread the word far and wide. How about a temporary statutory defence (for THC detection) being afforded to participants registered in the studies recommended and supported by the Victorian parliamentary review and similar studies (seemingly) endorsed by the NSW review and soon to be debated on the floor of Parliament?

The more people who don’t have to put their regular lives on hold in order to wind back the mysteries and wonder of cannabinoid science, the faster the damn research is going to get done.

The biggest hidden hold up to the research is securing clinical trial participants for a THC and driving study. A study which would prevent them from driving whilst the research is being carried out. If parliamentarians allow absurdities like this to stand then our grandchildren are on track to living in an idiocracy where sugary electrolyte drinks are what plants crave.

Instead of being quiet and patiently waiting for Bunsen and Beaker to turn in their paper, we in NSW and Victoria can ensure our votes go to candidates with some chance of setting up a balance of power in upcoming state elections. The Queensland government are about to announce a parliamentary review into drug driving laws and medicinal cannabis. Maybe that review will involve some genuine consideration of the practicalities involved with implementing an interim regime based on best practices from Norway, New Zealand, Canada and Ireland. Perhaps the per se limit of 3ug/L THC in blood as is used in the Netherlands could be a good starting point. If you consumed THC within the last 15 hours, you’ll likely get pinged.

Any researchers who wish to assail me on the accuracy of that, please provide your own estimates of when the average male and female who are daily consumers of, say 20mg of THC would ordinarily be safe to drive after their last puff on the Mighty Medic. The Dutch have gone with 15 hours, based on what we know of vaporised ingestion of THC, is there any chance of bringing that non-drive time down under 10 hours? 4-6 even?

Internationally, blood draws are common.

The logistics for increased use of blood draws in Australia are many, complex but not insurmountable. Anyone suspected of impaired driving can be sent off for bloods under current laws. It’s just that if we sent every person who returned a THC positive in saliva off for a blood draw – it would cost lots of money that governments don’t wish to spend and involve police time that the police would prefer to invest elsewhere.

Any relief against the current zero tolerance regime will be welcome, even if that is by way of a very broad legal limit of THC in blood that doesn’t yet have a strong correlation to being unsafe to drive, yet serves the purpose of deterring people from consuming THC and driving within timeframes where they may be impaired. Hopefully, researchers can narrow that window down further from 15 hours but until they do, perhaps this is where the compromise lies.

Until such an interim compromise is reached, outcomes for people like Will only serve to undermine the rule of law.

What do those words actually mean?

It’s problematic for faith in our courts if growing numbers of people feel that the rule of law is not there to protect them but is seemingly out to harm them by removing their right to drive a vehicle and participate in as functional a life as possible. The more people who feel that way, the more that the laws are ignored and violated to the point where they’re still “good law” but they are becoming increasingly ineffective as laws-to-be-obeyed because knee-jerk adherence to the rule of law is undermined by the unjustness of it all.

When punishment that is solely punitive (and not at all remedial) is handed down by courts to people that the overwhelming majority of the population don’t deem to have acted like criminals – that’s when you can say the rule of law has been undermined. When judicial officers step down (thank you David) rather than continue to apply such laws, that’s the alert signal that the undermining is happening right now.

Please continue to forward your hard luck medicinal cannabis and driving matters onto me. The facts will come and the law must change.

Mat Henderson is the principal lawyer of Reparation Legal and legal lead for Drive Change. Writing on Gadigal Lands and Waters. Always was, always will be. Ka nui te mihi ki a koutou.

*Although ostensibly an article about THC and drug driving law reform, nothing herein is intended to be construed as legal advice. Everyone’s circumstances are unique to them and unique to the idiosyncratic processes by law enforcement in every state/territory. If you need that advice, then by all means contact me.

Don’t print this off and wave it in front of a police officer’s face as if it’s the Magna Carta because it isn’t.

**If your medicinal cannabis prescriber does not wish to provide a letter to the court or if they wish to charge you for the privilege, then also please contact me. If your doctor is seeking guidance on how to write such a letter, have them get in touch with Drive Change.

The Cannabis Industry’s Survival Depends on The Drug Driving Laws

Read time: 3 minutes

As medicinal cannabis becomes a more popular solution for patients and prescribers, it also becomes a bigger source of economic growth. Last month, industry leaders gathered together at the Australian Medicinal Cannabis Symposium to discuss triumphs and roadblocks of the budding medicinal cannabis industry. Drive Change lead and former magistrate David Heilpern was there to share his insight on how discriminatory drug driving laws are harming patients, public health, and economic growth.

“This is an industry that’s starting to attract big business from funders who obviously see it as financially viable,” said David Heilpern, referencing medicinal cannabis investors, “I think they’re kidding themselves while these drug-driving laws are there.”

road closed sign

ALSO READ: Where Medicinal Cannabis is Legal, Roads Are Not More Dangerous

Of course, it’s not just the industry that these drug-driving laws harm, but individual patients and entire communities. Most patients who deal with pain rely on driving to work or just living their daily lives. Though medicinal cannabis remains an illegal substance in the eyes of road police, other impairing pharmaceutical drugs–and drivers who take them–are well within their right to drive while using their medication.  These alternatives include benzodiazepines or opioids, both proven through extensive scientific studies to have a greater impairing effect on drivers than cannabis.

david heilpern headshot
David Heilpern is a staunch advocate for fair and equal drug driving laws.

“If it was about road safety, it would apply to other prescription drugs,” Heilpern said of the current drug-driving laws before asking rhetorically, “so who wins from this?”

The answer, of course, is clear. Pharmaceutical companies who make and distribute drugs like opiates, benzodiazepines, and other impairing drugs have monopolised the healthcare system for decades. For many years, these drugs were doctors’ and patients’ only options for combatting pain. We know better now.

“Most people using medicinal cannabis were using pharmaceutical drugs to start with. And they’ll go back to them, even though the evidence is that those drugs have a greater impact on their driving.”

David Heilpern

According to the TGA, clinical studies have proven that patients who are prescribed medicinal cannabis report up to a 50% reduction in pain (especially for neuropathic pain, arthritis, and fibromyalgia); improved sleep and quality of life; and improved anxiety symptoms. Medicinal cannabis has also shown efficacy in reducing symptoms of epilepsy and muscular sclerosis, and it can alleviate the side effects of chemotherapy for cancer patients (although this practice is not yet approved in Australia).

Many patients find better relief from their pain and discomfort when taking medicinal cannabis than traditional drugs, and enjoy a life free from the cumbersome side effects. Unfortunately, because of the law, they have no choice but to deny medicinal cannabis prescriptions.

ALSO READ: Doctor, Patient, Advocate–A Physician’s Experience with Medicinal Cannabis

“Patients go back to their opioids and they drive on the roads probably far more dangerous than they would have if they had taken that [medicinal cannabis] prescription,” he added. 

Legislators continue to argue that medicinal cannabis is going to be a problem–but places where it is legal prove the opposite. We don’t even have to look far to see the effects of legal prescription cannabis in drivers. Tasmania legalised medicinal cannabis on the road in 2020. 

They have seen no increase in road toll since. 

How can we catch up on the mainland? Now that the tides have changed in government, we might have a chance to have our cause heard. 

Now more than ever it’s important to write to your local member. Let them know how the drug driving laws affect you, your family, or your loved ones, and direct them to scientific research to back your claims. 

You’ll find all the details you need on our BetterLetters campaign page. All you need to do is send the letter and start urging them for change. 

If Tasmania can do it, so can the rest of Australia.

CONTINUE READING: How the Current Drug Driving Laws are Failing Us

These Two Bills Could Be Crucial for the Future of Medicinal Cannabis

Read time: 2 min

Last year, we saw our ambassador Cate Faehrmann call on officials to throw out all the roadside drug tests in Nimbin during Mardi Grass weekend, citing contamination. Now, she’s taking an even bigger swing at the unjust drug driving laws with the introduction of two new bills, and one of them may help us see our goal of more effective laws being realised.

The Road Transport Amendment Bill

The “Road Transport Amendment Bill” aims to give medicinal cannabis patients the same rights as any other patients in Australia who take prescription medicine. This means that they will not be penalised for driving if they have a valid prescription and can prove they are not impaired–the rights that all other patients also have.

Writing a letter can be critical for the outcome of this debate in parliament.

Cate Faehrmann’s stance on drug laws in Australia align with the work of Drive Change.

A member of the Greens NSW, Cate Faehrmann is a vocal proponent of drug reform. She has introduced several bills throughout her career, but this one truly gets to the heart of the matter for medicinal cannabis patients and their rights to drive, something she says is “long overdue and increasingly urgent.”

This bill would amend our current driving laws, making them safer than they currently are and giving rights to medicinal cannabis patients. Drivers today are limited to medical options, like benzodiazepines, opiates, and morphine–which pose an even greater threat to road safety.

“I urge the Government and Opposition to assess my bill with compassion and common sense.”

Cate faehrmann, MP

“Roadside drug tests are incredibly sensitive. Patients can test positive 24 hours or more after they have consumed cannabis, well after any impairment has worn off.”

Cate Faehrmann uses scientific research to support the latest bills, and states: “This bill would simply provide the same medical defence that is already given to morphine patients. Medicinal cannabis is far safer than morphine on and off the road, but medicinal cannabis patients who test positive face damaging drug driving charges.”

If it passes, this bill will finally grant legal defence to medicinal cannabis patients who test positive in roadside tests, so long as they are within their legal rights and they are not impaired. Currently, the only state which grants this protection to medicinal cannabis patients in Tasmania.

Seeing this bill brought to the government means we may be able to see change soon, but it’s not guaranteed yet. 

“It should have happened when medicinal cannabis was legalised at the federal level in 2016,” Cate Faehrmann says. “Instead medicinal cannabis patients have been discriminated against and forced not to drive because our laws haven’t kept up.”

What you can do to show support

As the government deliberates their stance on this bill, the community can urge them to enact the change we desperately need. Writing to your local MP is one way to ensure they know the community supports the implementation of these amended driving laws. 

>Click here to get started!<

In conjunction with the Road Transport Amendment Bill, Ms Faehrmann also introduced the Cannabis Industry Bill 2021. This second bill aims to legalise medicinal cannabis for personal use. Though this would be an important step forward, protecting existing medicinal cannabis patients, many who have long been dealing with discrimination on the roadsides, is where we need to keep our focus.

Both of these bills will be up for debate in 2022.

4 Questions That Uncover the Problem With Our Current Drug Driving Laws (& Medicinal Cannabis)

Read time: 2.8 min read

This article is written by Drive Change ambassador Michael White. Below, he shares his experienced insight and analysis of recent data on medicinal cannabis and its effects on driving.

As a person who has been involved in drug-driving policy and research for over 25 years, I have recently been asked to provide answers to the following four questions in relation to the road-safety implications of driving after using cannabis. 

These are probing questions that get to the heart of the matter. They are the questions that policy makers need answers to, if they are to develop evidence-based policies in relation to driving after the use of cannabis.

Q1. Does research show that risk of crashing when there is THC in the bloodstream are significantly higher than when there is no THC in the bloodstream (based on an unbiased odds-ratio calculation)? 

My answer is ‘no’ – when study biases are taken into account. 

In other words, the presence of THC in the blood is not associated with a higher risk (odds ratio) of crashing. To come to this conclusion I reference a recently completed epidemiological review1 of the cannabis-crash literature that I have co-authored with my colleague Prof Nick Burns (White & Burns, 2021), which is that the null-hypothesis (cannabis-crash odds ratio = 1.0) cannot be rejected. 

However, that statement of our conclusion is, of course, compatible with the true odds ratio being slightly greater than 1.0 – such as 1.2. However, my opinion is that the true odds ratio most probably really is 1.0. 

Q2. Does research show that driving performance is degraded when there is THC in the bloodstream compared to when there is no THC in the bloodstream?

Yes, so we have a problem. 

Why does the degradation of performance (impairment) not increase the cannabis-crash odds ratio? There are many things to be taken into account. Cannabis users are not inclined to drive soon after using, especially if they feel intoxicated. Cannabis impairment is generally weak, and probably normally below a threshold where driving performance is dangerously degraded. 

Furthermore, while there could be a small increase in crash risk due to impairment, it is probably balanced by a small decrease in crash risk due to more cautious driving (as demonstrated by slower travelling speeds and greater headways).2

Given the role of speed in crash causation, a little extra caution could go a long way. Nick Burns and I are working together again to review the literature of the impairing effects of cannabis.

Q3. If medicinal cannabis has effects on driving performance, then is there a time window after ingestion of THC when impairment is most likely to degrade driving performance? 

Yes, there is a time window. Its duration has been explored in a couple of recent reviews.3 4 The most conclusive evidence we have so far is this:

For smoked cannabis, it is probably about three hours from the moment it is ingested. For edibles, such as cookies, it is probably a bit longer, starting after a delay of at least half-an-hour. The two aforementioned reviews also indicate that low-level impairment can, in some cases, last beyond three or four hours.

Q4. Does a performance-based test exist which can measure any decrease in performance that might arise from having THC in the bloodstream?

No. There is too much individual variation in any performance tests and too much individual variation to be able to accurately gauge levels of THC impairment. However, the answer could possibly be ‘yes’ if baseline levels of performance could be established for individuals. 

Still, even then, the measured performance decrement due to THC would probably be irrelevant to crash risk.  

There is a smartphone app known as the ‘DRUID test’ that seems to be popular in some quarters for measuring driver impairment. A recently published paper that includes an evaluation of the test can be viewed from the journal’s website here.

  1. For a copy of this review, please email a request to
  2. White, M. A., & Burns, N. R. (2021). The risk of being culpable for or involved in a road crash after using cannabis: A systematic review and meta-analyses. Submitted for publication.
  3. Eadie, L., Lo, L. A., Christiansen, A., Brubacher, J. R., Barr, A. M., Panenka, W. J., & MacCallum, C. A. (2021). Duration of neurocognitive impairment with medical cannabis use: A scoping review. Frontiers in Psychiatry, 12, Article 638962.
  4. McCartney, D., Arkell, T. R., Irwin, C., & McGregor, I. S. (2021). Determining the magnitude and duration of acute delta-9-tetrahydrocannabinol-induced driving and cognitive impairment: A systematic and meta-analytic review. Neuroscience and Biobehavioral Reviews, in press.

One Size Does Not Fit All: Mick Palmer on the Need for Fit-For-Purpose Driving Laws in Australia

Read time: 3 minutes

This article is written by Drive Change ambassador and former Commission of the Australian Federal Police, Mick Palmer. Below, he shares his take on where the laws need improvement to protect medicinal cannabis patients and the community on the road.

There is a clear and well-understood correlation between impaired driving and road safety. Australia’s road toll is of broad community concern, and the Government’s effective policies–like the .05 drink driving legislation and speed cameras– should be applauded. However, Australia’s ‘zero-tolerance’ drug driving policy creates trouble for both patients and police. 


The government has already allowed for doctor-approved access to medicinal cannabis. This comes in response to the ever-growing scientific evidence, in addition to anecdotal evidence, that medicinal cannabis provides relief for people experiencing genuine pain and suffering due to a range of health issues, including terminal illness.

The government’s recognition of this evidence provides a step toward relief for thousands of Australians. However, for the legality of medicinal cannabis to fully operate as intended, the roadside drug testing protocol urgently requires amendment. 

I am not suggesting impaired driving laws should be weakened, but rather that they are updated to fit-for-purpose and aimed at achieving intended outcomes. 

To become fit-for-purpose, retain credibility, and operate fairly, driving laws must be aimed at dealing with impaired driving. Until this happens, many law-abiding Australians suffering from illness and often extreme pain will continue to experience legal and physical distress as a direct result of the discriminatory drug driving laws. 

“Police Leniency”

Likewise, police have a clear responsibility to effectively manage and apply the legislation in the community interest. The truth is that police exercise considerable compassionate discretion in their enforcement of drug driving laws every day. This is, in part, due to the driving laws being unfit-for-purpose and in need of review and amendment, or repeal.

The role of the police is to enforce laws, not make them. It is certainly a recipe for inconsistency to expect the police to cure legislative deficiencies by making personal judgments on patients. 

Furthermore, if police are screening for medicinal cannabis use but not for impairment, the laws are unfit-for-purpose and end up punishing people already coping with a terminal illness or serious pain.

Medicinal cannabis patients should not need to rely on the favourable exercise of discretion by police to escape punishment. It is up to Governments to have the courage and decency to legislate the necessary changes.

“Necessary Changes”

If there is any chance that medicinal cannabis can help people with terminal illness or serious pain, to lessen their pain and suffering and improve their quality of life, we should, as an educated and compassionate society, do all that is reasonably possible to facilitate access. 

The fact that these current drug driving laws exist is sufficient for many patients who qualify for medicinal cannabis treatment to decide not to take their medication. 

Some of these patients need to drive their motor vehicles as a matter of daily necessity. Sufferers should not be forced into situations where they may end up breaking the law to gain relief. Surely this is not the government’s intention.

The reality of current roadside testing is that they are not only discriminatory, but also invariably lead to further distress, fear, and embarrassment for the patients.

The resulting pain and suffering achieve the exact opposite of the intention of Governments in allowing legal access to medicinal cannabis in the first place. I am personally confident that this also is not the intention.

The facts speak for themselves. There is a better way to uphold law and road safety. We must be prepared to explore the options. 

As an example, Norway has successfully been assessing drug levels in driver’s systems for many years. This surely is far preferable to the continuation of a “zero-tolerance” approach that we have here, which can only be beaten by judicial discretion.

The current medicinal cannabis drug testing laws need to be subject to urgent review. By amending the laws, we move to ensure they operate fairly and without discrimination while continuing to achieve the intended outcome of controlling impaired and potentially dangerous driving.