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Your AI is making up planning rules. Maybe.

Guide

Oct 14, 2026

Ask a chatbot the minimum lot size in a Brisbane low density zone and it will give you a number. It will be confident, well written and fast. It may also be wrong, out of date, or from another council.

The “maybe” in the title is deliberate. We could not find a public study of how often chatbots get Queensland planning rules wrong, or a reported case of a developer who lost money on an invented setback. What exists is a clear record of the same tools inventing law in Queensland tribunals, and a planning system that is unusually hard for them to read. This article sets out both, and a way to check.

It has already happened here

In March 2025 a party before the Queensland Civil and Administrative Tribunal relied on a Court of Appeal case that did not exist. The Deputy President put the citation into ChatGPT, which described the non-existent case in confident detail. The Queensland Law Society’s journal reported the warning that followed.

In October 2025 a Brisbane unit owner had a body corporate dispute dismissed after filing an application built on cases that could not be found and legislation that did not say what was claimed. According to a strata law firm’s account of the decision, the adjudicator inferred that AI had been used and ordered $2,000 in costs.

Professionals have been caught too. In 2025 Deloitte agreed to repay part of a fee of about $440,000 to the Australian Government after a report was found to contain references to sources that did not exist. A Victorian solicitor had his practising certificate restricted after giving a court an AI-generated list of authorities.

None of these is a planning matter. They show the pattern: a specific, checkable reference, stated with confidence, that turns out not to exist.

What the courts now say

Queensland Courts publish guidelines on generative AI for people who are not lawyers. They were revised in September 2025 and apply in the Planning and Environment Court. They name ChatGPT, Claude, Copilot and Gemini. In plain terms they say chatbots are not search engines, do not draw on authoritative databases, may be working from old information or from overseas law, and are known to produce cases and quotes that are not real. Responsibility for accuracy stays with the person who files the document.

The Planning and Environment Court went further the same month. Its practice direction on the accuracy of references requires a named person to take responsibility for every written submission, and warns of costs orders where material that does not exist is relied on.

What the research says

The best known work is from Stanford, and it concerns United States law.

A 2024 study found general chatbots gave wrong answers to between 69% and 88% of specific, checkable legal questions. They did worst on lower courts and less prominent cases, and tended to accept a false premise in the question.
A second study tested paid legal research tools that look up real documents before answering. They still got more than one answer in six wrong.
A 2026 benchmark of hard, multi-step questions found the best current model, with web search switched on, still made things up in roughly 30% of cases.

The models have improved since 2024, and those tests were built to be difficult. The lesson that carries over is the pattern. The more local and obscure the rule, the worse the answer. A setback in one council’s dwelling house code is about as local as a rule gets.

Why Queensland planning is hard for a chatbot

Every council writes its own rules. A minimum lot size in Brisbane is not the minimum in Logan or Moreton Bay. A chatbot that has read more about one will happily apply it to the other.

The rules keep changing. Brisbane City Plan 2014 reached version 37 on 18 September 2026. Council has published eight new versions since September 2024. Version 36, in June 2026, changed car parking rates for multiple dwellings. Version 37 changed design rules for low-medium density housing. Ipswich replaced its 2006 scheme with a new one on 1 July 2025. A chatbot’s knowledge stops at a date it may not tell you.

The state changed the house rules in September. The Queensland Housing Code started on 1 September 2026 with new statewide standards for setbacks, site cover, height and parking for houses and secondary dwellings. Councils have up to three years to adopt it. Until each one does, the old provisions apply in that council’s area. For the next three years the right answer to “what is the side setback” depends on which council has moved.

Some rules are not in the scheme. A temporary local planning instrument can suspend part of a scheme for up to two years without changing its text. Priority Development Areas have their own development schemes that override the council’s. State interests sit in separate state mapping.

Much of it lives in maps. Overlays for flood, bushfire, character and heritage are map layers tied to a lot. Brisbane publishes its plan as an interactive site, not a document. A chatbot cannot tell you which overlays touch your lot unless it has queried that mapping.

Councils are using AI too, with the same warning

Sunshine Coast Council launched an AI assistant for early planning enquiries in November 2025. Several Victorian councils run a similar tool. One of them, Yarra Ranges, tells users plainly that the result is preliminary, is not a planning decision, cannot see a property’s permit history, and should be reviewed by a planner. New South Wales is funding AI tools for councils and says planners review every output and decisions stay with people.

When the tools built for the job, on the council’s own data, tell you to verify, a general chatbot deserves at least the same caution.

How to use it without getting caught

Chatbots are useful for this work. They are good at summarising text you give them, explaining a term, and drafting a brief to a consultant. The risk is in asking them to recall a rule.

Give it the text. Paste the code section from the council’s own planning scheme site and ask for a summary. Do not ask it what the code says from memory.
Ask for the reference. Scheme name, version number, section and table. Then open that section. If it cannot give one, or the section does not say that, you have your answer.
Ask the question twice, differently. If the number changes, treat both as unverified.
Check the lot, not the zone. Brisbane’s City Plan online produces a property report by address, with zone, overlays and neighbourhood plan. Logan’s PD Hub does the same and is free. The state’s mapping shows state interests and referral triggers. BDRCK reads the same state and council services by address and shows the source beside each value, so you can open it and check.
Look at what was approved nearby. Brisbane, Sunshine Coast and Redland publish applications through Development.i. An approval on a similar lot in the same street tells you how the rules were applied in practice.
Ask a person before you spend money. Brisbane City Council runs free 15-minute Talk to a Planner sessions, and a paid preliminary discussion at $600 in 2026-27. A town planner’s hour costs less than a contract on the wrong assumption.