A group of angry ratepayers is asking the High Court to order the Northland Regional Council to refund rates it illegally set and collected for six years.
In September last year, the High Court in Whangarei ruled NRC rates for Kaipara were not lawfully set or assessed between 2011 and 2016, and that the errors were serious and substantial.
The interim ruling by Justice Ailsa Duffy followed an application for judicial review by the Mangawhai Ratepayers and Residents' Association, its chairman, Bruce Rogan, and his wife, Heather.
In the application the association and the Rogans argued the NRC rates' demand for those years did not state a calendar year by which each instalment of rates was to be paid.
The Rating Act says a local authority must state the financial year to which the rate applies and the date on which it must be paid.
The Kaipara, Whangarei and the Far North District Councils collect rates on behalf of NRC.
Some association members had paid rates and penalties before the High Court's ruling in September, while others refused to pay.
Next month Justice Duffy will hear submissions on what relief should be granted to the ratepayers.
"A local authority is bound by the law and is amenable to legal process in the same way as any commercial entity,'' Jeremy Browne, lawyer for the association and the Rogans, said in his submission.
"It should not be able to seek refuge from legal liability through claiming equitable remedies that effectively mean it is outside the rule of law."
He said while Parliament was aware local authorities would make errors, suffer financial loss and administrative inconvenience, it also provided them with statutory remedies to replace defective rates, defective rates assessment notices and rates invoices.
In recent years, several validation acts passed by Parliament validated such irregularities.
"These enactments should have been a lesson to all local authorities to check their rating processes for compliance, especially the NRC and KDC because they were directly involved with the Kaipara Validation Act,'' Mr Browne said.