Ms Gallagher told the ACT Legislative Assembly on Wednesday the 25-bed unit will be "an incredibly hard service to run" and the territory would have to train specialist workers due to a shortage of qualified forensic staff in the ACT.

The Health Minister made the comments as the Assembly agreed to construction of the medium secure unit on the former Quamby detention centre site and consideration of special legislation to speed up the project.

The opposition voted in favour of the government motion, giving in principle support to the use of project specific legislation to bring the completion date forward from its current deadline of May 2017.

But opposition leader Jeremy Hanson called for the Assembly "to condemn" Ms Gallagher for delays to the much-needed facility.

"Not only has it taken the government eight years to stop dragging their feet, it's taken a number of serious incidents," Mr Hanson said.

"This isn't just about the dollars, this isn't just about delays in construction and the budget.

"We need to remember the impact on people."

Mr Hanson said Ms Gallagher should "stand up in this place, acknowledge the mistakes and say, yep, we've stuffed it up."

Wednesday's debate in the Assembly followed the first prisoner suicide in Canberra's jail last month and a spate of incidents at Canberra's adult mental health unit.

Ms Gallagher said Mr Hanson had shown no interest in mental health "unless issues are raised in The Canberra Times." The Chief Minister called for a "realistic grip" on the problem, noting several forensic services were already operating in the ACT.

Ms Gallagher said she was "guilty of taking my time to get this project right''.

"Because it will be an incredibly hard service to run," she said.

"It will be an incredibly hard service to staff. We don't have the staff available …

''We will have to train our own staff because of how hard it is to get people into these positions."

The opposition also used Wednesday's Assembly sitting to renew its calls for an ACT Auditor General's review of Canberra's emergency department wait times.

The government and Greens minister Shane Rattenbury used their numbers to defeat the motion.

It was the second opposition attempt this year to force an auditor-general's review of Canberra emergency departments.

Mr Hanson said a recent report that found the government had ignored advice on the location of its nurse-led walk-in centre showed the system needed an inquiry.

The report found the ACT's first walk-in centre had created more work for the Canberra Hospital's emergency department.

"I hope by continuing to apply pressure on the government to take this issue seriously, to take the action that's needed to be taken, that eventually they will make the right decision," Mr Hanson said.