Douglas Council has been told to rethink its response to a Freedom of Information request.
Someone wanted information about building control checks at the former Nurses Home development on Westmoreland Road.
But the local authority refused to provide details, saying it was exempt and releasing it would reveal trade secrets.
However, Information Commissioner Dr Alexandra Delaney-Bhattacharya said the exemption hadn't been applied properly, adding the council must now re-process the request and provide a new response.
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