Australia’s “disproportionate” drug driving laws should be overhauled as part of a proposal to legalise recreational cannabis use for adults in the ACT

Under a law proposed by Labor backbencher Michael Pettersson, residents would be legally allowed to carry up to 50 grams of cannabis and would be allowed cultivate up to four plants at their home - the sale of the drug would remain illegal.

The inquiry has generated a lot of interest, with the ACT Law Society saying drug driving laws need to be amended ahead of changes.

Australia's current drug driving laws do not accurately determine impairment argue lawyers. (9news)

“Penalties imposed for committing a drug driving offence are disproportionate because they do not account for levels of cannabis impairment and intoxication,” the authors of the submission wrote, highlighting police only test for the mere presence of the drug.

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The society added if a person smoked days before being stopped by police and still had “a small amount of cannabis in their system” but were "otherwise unimpaired”, they would still be subject to the same penalty as repeat offender drink drivers caught with 0.08 blood alcohol levels.

“The higher penalties for committing a drug driving offence may be justifiable in circumstances where a person is impaired and/or intoxicated due to consuming a ‘hard drug’ but not when a person drives with a low-level of cannabis in their body,” the submission stated.

Speaking at a Legislative Assembly committee late last month, ACT Law Society committee chair Michael Kukulies-Smith raised further concerns over the laws.

Legalising recreational weed would bring the ACT into line with ten US states, as well as the entire nations of Canada and Uruguay. (AP/AAP)

"Clearly alcohol is freely available to adults in our community and can be freely consumed by adults in our community but we still quite rightly have drink drive legislation that regulates and punishes people for the degree of impairment that they actually have rather than they have just engaged in their lawful right to consume a single drink," Mr Kukulies-Smith said, reported Canberra Times .

"The same thing could happen with the cannabis legislation - that a person lawfully has a joint one evening, they may not be affected at all the next day however under our current drug drive laws almost certainly if they were pulled over would be detected and guilty of an offence that's punished as if it was the highest or harshest drink driving offence that we have in the territory."

The move comes as a Michigan commission tasked with studying the effects of cannabis on driving has given the recommendation that the state – where marijuana is legal for recreational use - not impose limits on the amount of THC that can be present in drivers’ bodies.

After two years reviewing published scientific research and conducting roadside tests with the Michigan State Police, the Impaired Driving Safety Committee found THC levels are indicative of exposure, but “are not a reliable indicator of whether an individual is impaired”.

As it currently stands, drivers caught with traces of THC face the same penalty as repeat drink drivers. (NineSupplied)

The report said one of the biggest reasons there's a “very poor correlation" between THC and driving impairment was the long time frame the drug stays in the system of the user, which means it can be detected long after any effects have passed.

It added heavy cannabis users can have higher THC levels than inexperienced users without showing signs of impairment, so a positive test might not a fair indication.

The committee also discovered in its research that stoned drivers were less dangerous than those who get behind the wheel after drinking.

“Interestingly, in most of the simulator and vehicle studies, cannabis-impaired subjects typically drive slower, keep greater following distances, and take fewer risks than when sober. These effects appear to suggest that the drivers are attempting to compensate for the subjective effects of using cannabis,” the report explained.

“This is contrasted with alcohol-impaired subjects, who typically drive faster, follow more closely, and take more risks than when sober.”