Environment Minister Amy Adams is being accused of interfering in judicial independence for commenting on a council decision to prosecute a couple for felling trees.
Elderly Otaki couple Peter and Diana Standen cut down what they described as rotting and dangerous trees on their property but were then charged by the Kapiti Coast District Council for their actions - charges later withdrawn.
Ms Adams criticised the council decision to lay charges.
But Lawyer Richard Fowler, commissioned by the Kapiti Coast District Council to do a report into the incident, described her criticism as inappropriate and able to be perceived as an attempt to influence a court.
Mr Fowler said Ms Adams attacked the decision to prosecute even before a hearing was held, and such comments by a Minister of the Crown throw up all kinds of constitutional issues.
The council said it is using the report to form new policy.
That includes setting up a panel to thoroughly review any potential prosecutions.
Ms Adams could not be reached for comment.