But Liberal leader Jeremy Hanson has expressly ruled out such changes, saying "from our point of view, there would not be significant reform in the drug law area".

Mr Hanson, Chief Minister Andrew Barr, and Greens leader Shane Rattenbury appeared in the campaign's first major leaders debate on Monday night, hosted by the ACT Council of Social Service.

It was a debate focused on inequality, and the issues affecting Canberra's vulnerable and disadvantaged.

Labor used the event to pledge $1 million in grants to build bulk-billing GP centres in Tuggeranong and Molonglo if re-elected, and the Greens promise to freeze public transport fares and implement a housing affordability policy, which would place a member of the social and affordable housing sector on the Land Development Agency's board.

The Liberals confirmed they supported the government's goal of 100 per cent renewables by 2020 and zero emissions by 2050, and Mr Hanson said the "reality is that this is now legislated" and the "contracts are signed... so it's kind of happening whether we like it or not, but we are very happy to support that".

The debate was relatively polite with few direct conflicts between the leaders and no real blunders.

One area of obvious difference was exposed by a question from Families and Friends of Drug Law Reform president Peter Taylor, who asked the leaders on whether they would seek to further decriminalise drugs for personal use in the ACT.

Liberals leader Jeremy Hanson said he would not pursue such reforms.

"I'll give you a straight answer and the answer is no," he said.

"That's not to say we're not incredibly compassionate to people affected by the scourge of illicit drugs... I think when people are affected they need to be helped as much as they can through the health system, rehabilitation programs."

Chief Minister Andrew Barr said he didn't think the Mr Hanson's position was a "rational one" to take into the next term of parliament.

Mr Barr said he think the city was mature and ready for a discussion on such reforms, and noted that, philosophically and personally, he wanted to "at least have the debate".

"The ACT has in the past undertaken reforms that have decriminalised certain recreational drugs, and I think there's been a flow-on benefit from those decisions," he said.

"But the process needs to involve a broad community discussion, but I think there is a capacity to have that discussion in the city."

"Philosophically, my personal approach would be to want to have that discussion."

Greens leader Shane Rattenbury said the war on drugs was clearly not working, and the ACT needed to adopt a more effective and compassionate approach.

"Simply saying 'just say no', or just locking people up, is not the right response," he said.

Labor's flagship announcement on Monday night was a grant scheme to build bulk-billing GP centres in Canberra's south.

A grant of up to $1.05 million would see three new bulk-billing practices built. Two would be set up in Tuggeranong, and another in Molonglo Valley.

Centres that offer the "provision of low or no cost primary care services, such as psychology, diabetes support, and physiotherapy" would also be looked on favourably, Labor says.

"Labor has worked hard to encourage bulk-billing in the ACT. In 2009, the government awarded a $220,000 start-up capital grant to the National Health Co-op to establish its first facility in Charnwood. [It] will open its sixth clinic shortly," Mr Barr said.

"Other providers have also opened new GP practices in recent years."