Maori Council lawyer Felix Geiringer this morning challenged John Key's claim no one owns water and said the Prime Minister had misled the public on that point.
Justice Ronald Young is hearing in the High Court at Wellington the challenge to the Government's plan to partially privatise Mighty River Power next year taken by the council, the Waikato River and Dams Claims Trust and the Pouakani Claims Trust.
The council argues it is unlawful for the Government to sell shares in the company because that would affect the Government's ability to make redress for any Maori ownership claims over the Waikato River and other water bodies.
But Mr Key has dismissed the council's claims a number of times, saying his Government's view was that under common law no owned the water in rivers, lake and other water bodies.
But this morning Mr Geiringer said Mr Key was wrong, and his statements were an "error of law" and "meaningless".
Mr Geiringer said he believed Maori could potentially establish full blown ownership of water and his submissions included a number of examples of that.
But Mr Key's claim underpinned the three key decisions by his Government which the council is challenging in court which were;
# the decision to convert Mighty River Power into a "mixed ownership model" company which can be partially privatised,
# the decision not proceed with "Shares Plus" or any other mechanism for redressing Maori proprietary rights in water, and,
# the final decision to partially sell the company which is expected next year.
But Mr Geiringer said Mr Key had misled the public on the ownership of water.
"It's tricksy on behalf of the Prime Minister who pretended to the New Zealand public that he was basing his decision on the common law that no one owned the water when he wasn't really.
"In secret the Crown knew that it was possible to own water and therefore that formed no part of their decision-making but that's not what he told New Zealand."
However, Justice Young challenged Mr Geiringer's claims, asking him repeatedly to explain how Mr Key's statements were an error of law. That led to a heated exchange which ended only when Justice Young told an increasingly frustrated Mr Geiringer to" take a deep breath and count to 10" and to "remember where you are".
The Crown begins its submissions this afternoon and will argue the decisions being challenged by the council are not reviewable by the court as they have been endorsed by Parliament.