Auckland lines and gas company Vector wants to take the Commerce Commission to the Supreme Court over the way it regulates price setting for monopoly utility providers.
Vector began a judicial review into the rules and processes for setting starting prices in 2011, but an initial victory in the High Court was overturned by the Court of Appeal in early June.
Vector said its investment decisions were hindered by rules to set the starting price through the commission's input methodologies.
Chief executive Simon Mackenzie said Vector believed the High Court decision was robust and it would appeal to the Supreme Court for a final decision.
"The inclusion of a starting price methodology in the input methodologies framework is fundamental to a good regulatory regime and in our view this was implicit in the decision to make the amendments to the Commerce Act in 2008."
The commission had appealed the High Court decision, saying it could potentially be required to develop other input methodologies it didn't believe Parliament intended.
NZN