Its campaign chairman, Richard Burton, also a planner by profession, insists it is not opposed to intensification, only to the council's latest move which he argues is undemocratic.
The Unitary Plan has been years in preparation and subject to public notification, submissions and hearings at every turn.
Until now, it seems. The proposed Unitary Plan is reaching its penultimate stage, a hearing of submissions to an Independent Hearings Panel led by an Environment Court judge.
The panel is due to report its conclusions to the council in July and and the council is supposed to finalise the Unitary Plan in August.
The move that has raised the alarm of Auckland 2040 is a late submission from the council to the panel that changes the zoning of many places to permit higher-density development than would have been permitted under the proposed Unitary Plan upon which all interested groups in the city have based their submissions to the panel.
The procedure laid down by law allows a council to make this sort of late "out-of-scope" submission, which give residents no rights of objection, but Mr Burton argues the legal provision exists for councils to fine-tune their proposed plan, not to, as he puts it, "introduce radical zoning changes by stealth".
He has a point. The areas subject to the changes, as shown on maps published in the Weekend Herald, are extensive.
But they appear more precisely considered than the blanket higher-density zoning that caused such alarm across the region when the plan was first drafted.
The outcry against the draft caused the council to scale back the plan drastically when it produced the plan proper in 2013.
That was an election year and the council may have been too weak. The Government, which blames Auckland house prices on an undersupply of housing in the city, has backed a submission to the panel from the Ministry for the Environment calling for higher-density development to be permitted in many desirable suburbs.
The panel has already asked the council whether its proposed plan is sufficient to accommodate Auckland's projected population growth over the next decade or so.
The council's late submission, approved by a small committee, amounts to a concession that the 2013 plan is not sufficient. Auckland 2040 (the date refers to the population growth horizon) disagrees, arguing the plan can handle the expected housing demand to 2026 at least.
It will be up to the panel to make an independent assessment. The council should not withdraw its late submission today. The panel should be given all available information, and this long tortuous exercise should come to a conclusion.