Labor MLA Michael Pettersson tabled an exposure draft of a private members bill in the ACT Legislative Assembly on Wednesday that would remove cannabis possession under 50g as an offence for adults.

It would also allow you to have up to four cannabis plants.

It has not been signed off on by cabinet nor is it official ACT Labor policy although Labor ministers Meegan Fitzharris and Mick Gentleman would not rule out supporting it.

Mr Barr told Canberra radio station 2CC he'd never smoked cannabis but was interested in progressive legislation.

“I think that idea has merit, we largely have that system in place in the ACT at the moment for personal use and it’s decriminalised and you just get a fine," Mr Barr said.

"The question that Mr Pettersson has raised through his private member's bill is whether in fact all of that effort around a fine is really worth the trouble.

"The other question we would need to consider is to what extent would this completely disrupt a business model that many suppliers are currently using and by disrupt I mean in a good way.

"If you take the money out of this and allow people to have a small amount of cannabis for personal use that they can grow themselves then they are less likely to be involved in a range of illegal activity particularly engaged with those seeking to cultivate and supply at a much greater scale."

The remarks were a departure from Mr Barr's previous disinterest in drug reform.

The chief minister was famously uninterested when the Australian-first pill trial at Groovin The Moo got the last-minute go-ahead in April.

Mr Barr also said he'd come around to the idea of pill testing since the trial was successful.

“I was I guess neutral on that question, I wanted to see how that trial went, I didn’t have a strong way one way or another. Having now seen the trial and seen the report of the trial I’m leaning now more in favour of further trials and pill testing occurring in the ACT," Mr Barr said.

Mr Barr said he was keen for a public discussion on the Pettersson bill.

"Politicians of all political persuasions have tried prohibition and what that has done is create a very profitable industry for those who will illegally supply drugs. I think there’s room for a change in approach," he said.

"I think it’s useful for there to be a public debate on this matter now, we’ll see how that unfolds but my starting place on this is to have an open mind and am leaning favourably disposed towards supporting such an outcome."

Clarification: The document tabled by Michael Pettersson was an exposure draft.