Councils have been warned to tighten planning procedures after the High Court found Brighton and Hove City Council guilty of ignoring new planning laws.
In a landmark ruling last week, the council was fined £30,000 for unlawfully authorising a major residential development - a verdict that could open the floodgates to a spate of claims.
The council was admonished by Mr Justice Sullivan after it failed to justify a decision allowing a £200,000 house to be demolished and replaced with luxury flats.
The judge declared that the council had not complied with an amendment to the General Development Procedure Order, made in December, forcing councillors to explain planning approvals fully.
Previously, councillors only had to give reasons for refusals.
Local resident Teresa Wall brought the case after fearing the development at Withdean in Brighton would dwarf her home and block natural light.
Her solicitor, Richard Buxton, believes more councils across the UK could face similar action because the new law is not widely known.
'The change to planning laws was designed to bring the UK in line with Europe, ' he said. 'However, the rules are not well known and councils may be operating in ignorance. I have certainly been dealing with another council where this is the case.' During the case against Brighton and Hove, planning committee members were forced to reconsider their reasons for supporting the scheme after their original explanations were proved to be factually incorrect.
'This ruling will force councils to declare decisions on planning applications there and then. It is absurd for them to give retrospective reasoning, ' Buxton added.
Brighton and Hove council has now warned UK planning committees to update procedures to avoid falling foul of the law.
A council spokeswoman said: 'The city's procedures are not unique and this judgment will have implications for all local planning authorities following similar practices.' However, Brian Waters, a member of the Association of Consultant Architects Planning Advisory Group, believes the High Court decision points to a much larger issue.
'The PPG 3 pressure for higher densities means that the issue of what is the appropriate form for higher-density replacements of big old houses or bungalows in towns and suburbs will probably be the biggest challenge for architects over the next decade, ' he said.