"If they were on sound ground, I believe they would provide a copy of the opinion."
Hawke's Bay Today also asked the council for a copy but was declined by the council's chief executive Ross McLeod.
"This is to protect legal professional privilege and specifically to protect council's interests in any legal action that might be brought against it," Mr McLeod said.
Mr Calver said the council also took legal advice on whether GST was payable and that information was supplied to land owners.
"The council needs to front up and say whether it is legally justified. They might have a lawyer who has a brilliant reason why the target rate is permissible."
Mr Calver said other property owners around the domain would have come to a different conclusion if they had "taken good advice". He thought the council misled them with the idea that the domain might otherwise be developed, on the assumption this would devalue existing housing.
"The contrary argument could be that development may have enhanced the value of the properties along Airini Rd."