Despite the ACT government's attempts to push the laws through quickly, the Assembly sent them to the planning committee for an inquiry after Mr Rattenbury came under pressure from planning and heritage groups.

Now Mr Rattenbury faces doubters within his own party, with former Greens Assembly member Caroline Le Couteur warning the laws will politicise planning, and leave the government with a conflict of interest as both landowner and planner.

Ms Le Couteur made a submission to the inquiry, which is due to report on May 6. The committee received 21 submissions, among them strong opposition from the city's community councils, which say the planning bill is rushed and open to abuse.

The bill, which has already been agreed in principle by the Assembly, would allow the government to declare special precincts and major projects that would not be subject to the usual planning rules, going instead to the Assembly - a move that critics say politicises planning.

Laws protecting heritage buildings and significant trees would be bypassed, and decisions could not be appealed to tribunals and courts.

Ms Le Couteur said the most worrying aspect was the ability for the government to change the Territory Plan without review or appeal. The government's justification - that it needed to push through a new mental health unit at Symonston - did not justify the change, she said, with plans for the unit around for about five years, plenty of time for a Territory Plan change.

The government plans to use the new powers to develop Northbourne Avenue and a new rail line from Gungahlin to the city. But Ms Le Couteur said Northbourne had tree and heritage issues, was the entrance to the city and home to thousands.

"The government has potential conflicts of interest as it is the owner of most of the land and seeking to get the best financial return on one hand," she said. "However, as the local government it is also the provider of a public transport system and guardian of planning outcomes such as the provision of public housing for the whole city."

Five community councils and other neighbourhood groups raised objections to the laws, largely on the rush in pushing them through the Assembly, the lack of consultation on planning decisions, and the concentration of power in the hands of the government. Labor and Mr Rattenbury have justified the rush because of the urgency of a new mental health unit, but Weston Creek Community Council chairman Tom Anderson said that rather than using the mental health unit as justification for a new planning regime, if it was urgent it could be cut from planning laws and dealt with separately.

Griffith Narrabundah Community Association president John Edquist said it was "at best misleading" to claim the mental health unit as an example of the kind of project to be approved under the new system, since the bill treated the mental health unit differently, giving it faster treatment than other projects.

Mr Rattenbury has defended the new system as better than the "call-in" powers the government has to shortcut planning.

But the councils and others say the call-in powers remain. The justification was disingenuous, Mr Anderson said. "It's like comparing two totalitarian regimes - both are fundamentally bad and run counter to responsible governance."