Lawyers for Te Whanau a Apanui and Greenpeace are preparing to wait weeks for a judge to decide whether or not the Government followed appropriate steps when it issued an oil exploration permit.
They want the judge to quash the oil exploration permit granted to the Brazilian energy firm, Petrobras, which is searching for oil in the Raukumara Basin.
The hearing in the High Court in Wellington started on Tuesday.
The tribe's lawyers began first, arguing that the Crown did not properly consult the iwi, it didn't consider treaty obligations, or thought through the impact of any oil spill on marine species and the environment.
In response, lawyers acting for the Crown say the eastern Bay of Plenty iwi, Te Whanau a Apanui, didn't respond to a government invitation to talk about plans for oil exploration, which the lawyers say would have helped pin-point important places to the iwi.
The Crown also rejects a claim that former Energy and Resources Minister Gerry Brownlee did not consider what harm could come to the environment before he issued the permit.
Defence lawyers say his job was to look at the potential of petroleum resources.
They say, generally, an environmental impact assessment is carried out by the company as part of Maritime New Zealand regulations at least two months before drilling.