A Government minister issued an oil exploration permit without investigating the possible dangers an oil spill might pose to the east coast of the North Island, a court has been told.
Maori tribe Te Whanau-a-Apanui and environmental group Greenpeace have asked a judge to quash a five-year permit issued to Brazilian energy company Petrobras in 2010.
The case began in the Wellington High Court on Tuesday.
The iwi's lawyers claim that the Crown failed to tell it about the granting of an exploration permit for the Raukumara Basin in line with Treaty of Waitangi obligations.
However, lawyers for the Crown reject the claim it had to consult iwi about the granting of a permit. They say Te Whanau-a-Apanui was told about the permit being offered on an open market.
A lawyer representing the iwi and Greenpeace told Justice Gendall on Tuesday that former Minister of Energy and Resources Gerry Brownlee did not thoroughly look at the risk of any oil spill before granting the permit.
Davey Salmon says if seismic drilling is undertaken, there is a risk of an oil spill which could stretch as far as the Australian territorial waters of Norfolk Island and as far south as Christchurch.
Mr Salmon says that is significant in legal terms - because once pollution extends past New Zealand waters, a sweep of international treaty obligations come into effect. He says his clients believe that scenario was missed by Mr Brownlee.
Lawyers for the parties also questioned whether the minister considered the environmental risk of seismic drilling to marine species such as fish and whale which are treasured by Te Whanau-a-Apanui.
The Crown and Petrobras are due to make their submissions on Wednesday.
Consultation key aspect, says iwi's lawyer
A lawyer for Te Whanau-a-Apanui says the issue of consultation is key to the case. She says the iwi believes government departments have an obligation to consult with tribes over mineral resources in their tribal rohe (district).
Dayle Takitimu says that position is backed by the United Nations Declaration on the Rights of Indigenous Peoples - which the New Zealand Government supported before allowing Petrobras to look for oil.
Petrobras is analysing data from the survey it carried out in 2011.
Earlier satellite, seismic and magnetic data compiled by GNS Science suggests there is an active petroleum system in the Raukumara Basin. It says there are indications of hydrocarbons - suggesting they potentially contain large volumes of oil and gas.
In April last year, Te Whanau-a-Apanui and Greenpeace carried out direct action against the survey, launching protest flotilla and at one stage swimming in front of a survey vessel.