ACT Labor backbencher Michael Pettersson's bill to legalise cannabis is based on the Vermont model, which allows for the possession and use of cannabis but does not create a commercial market.

While legalisation in Vermont came in the context of similar moves from other US states and under a different federal framework (Congress legalised the production of hemp, a form of cannabis with lower THC levels, in December), stakeholders say there are lessons the Australian capital can learn from their experience.

As the law had only been in force since July, there was not a "large body of data to look at" on how the legislation is working, the director of the Vermont Coalition to Regulate Marijuana Laura Subin said.

But there had not been reports of a surge in cannabis-related driving incidents or use rates or "any of the other litany of ills we were warned to expect".

"Instead, poor communities of colour are no longer suffering disproportionately from the failed system of prohibition," Ms Subin said.

"Under that system, African Americans in Vermont were being arrested at more than four times the rates of whites according the American Civil Liberties Union and the fees associated with marijuana violations were equivalent to a week's worth of wages for those making minimum wage in Vermont.

"Perhaps what is more significant is what didn't happen when Vermont legalised cannabis. Contrary to the dire predictions made by prohibitionists, the sky did not fall and things are largely as they were."

However Vermont State Police dispute that they targeted users before the legalisation.

Vermont State Police public information officer Adam Silverman said before the legalisation of cannabis, primary investigations were based on the cultivation of marijuana or those trafficking the drug.

"Very rarely were people targeted as individual users unless it was a result of a motor vehicle stop," Mr Silverman said.

"Even prior to legalisation, the primary focus in Vermont was on opioid investigations. Marijuana investigations still are conducted based on larger illegal sale and cultivation circumstances."

Mr Silverman also said it was too early for firm data on how legalisation was working, although there had been an "uptick" in the number of butane hash oil laboratories uncovered, some of which led to fires or explosions.

The number of fatal crashes involving drug impairment surpassed the number involving alcohol impairment in 2014.

"Meanwhile, the perception of harm among Vermont youth has led to more juveniles reporting being in vehicles with a driver who has smoked marijuana. These rates are double those of juveniles who report being in vehicles with a driver who has consumed alcohol," Mr Silverman said.

"The decreasing perception of harm is also evidenced in self-reported prevalence of driving after using marijuana versus driving after drinking alcohol - about 15 per cent for marijuana, and 7 per cent for alcohol."

He said one lesson Canberra could take from Vermont is that the legislation must clearly address roadside impairment testing for marijuana and issues regarding prosecution of driving under the influence of drugs.

However Vermont's Lieutenant Governor David Zuckerman put the increases down to changes in reporting methods.

"The reality is people were using cannabis in Vermont before the law changed so we have really seen no changes in the areas you mention," Lt. Gov. Zuckerman said.

"There is some change in reporting so we see a slight increase in some areas, again it is because people are identifying the substance now and before there was just one category."

The Vermont Progressive Party politician was instrumental in the legalisation of the drug, and said their next step was to create a retail system.

Already, businesses had tried to get around the ban on sales by selling people miscellaneous items like stickers and "gifting" cannabis as part of the exchange.

"The attorney general quickly wrote a brief stating this was not allowed," Lt. Gov. Zuckerman said.

That kind of entrepreneurship and the impracticality of addressing such legal grey areas made the move to a system of regulated sales the next logical step, Ms Subin said.

"This is one of the reasons that our Attorney General's views on legalisation have evolved. He now supports a full system of taxed and regulated sales to adults," she said.

She said a regulated system would be the best way to "promote consumer safety, prevent underage use and contribute to economic growth".

However regulation should prioritise access for those who suffered most under prohibition, Ms Subin said.

"Some of the ways this can be done is by prioritising minority owned businesses for licenses and/or creating lending programs for those wishing to start businesses in under-served communities," Ms Subin said.

"I also hope that our system will provide adequate access for small Vermont farms and limit large national and multi national corporations to the greatest extent possible. This can be accomplished by creating tiered licensing systems and issuing an unlimited number of the smallest tier licenses while limiting the number of larger scale licenses.

"Ongoing criminal justice reforms- such as automatic, cost free, expungement of prior marijuana convictions, and reduction in the penalties for possession just about the legal limits - are also essential."

An ACT Legislative Assembly inquiry into Mr Pettersson's cannabis bill will begin on March 26.