The High Court has quashed a ministerial decision to decline an application for a marine reserve in Akaroa Harbour.
In a decision released by Justice Christian Whata, the court has ruled in favour of an appeal by the Akaroa Marine Protection Society.
The society has been lobbying for a 530-hectare reserve for more than 20 years that would protect 12% of the harbour from fishing.
It sought a judicial review after its application was declined in 2010 by Conservation Minister Kate Wilkinson.
In his ruling on Tuesday Justice Whata overturned the decision, saying Ms Wilkinson was wrong to consider only the potential negative impact on recreational fishers and ordered that she needed to take into account the wider benefits of the proposed reserve.
The Akaroa Marine Protection Society welcomes the ruling and is looking forward to the minister taking another look at the proposal. Spokesperson Kathleen Reid says it remains optimistic there will be a reserve.
"This is really our last chance to do something meaningful in the harbour and hopefully go some way towards restoring the degradation that's been happening over the years."
Kate Wilkinson says she based her decision on advice given at the time and has not yet had a chance to look at the court ruling.