The Environmental Protection Authority has rejected accusations from Greenpeace that it failed in its legal responsibilities by granting Anadarko permission to drill for oil off the coast of Raglan.
A judicial review of the decision is under way at the High Court in Wellington on Monday.
Greenpeace's lawyers have argued that the authority made a legal error by granting permission for the drilling without seeing documents provided to Maritime New Zealand about the effects of a potential oil spill and how it would be managed.
But the EPA said it is the responsibility of Maritime New Zealand to deal with spills. It argues that the documents were of marginal relevance, highly technical and in draft form.
The authority says its decision did include a summary of the most important points from the documents.
Greenpeace says the authority shouldn't be allowed to delegate its responsibility because Maritime New Zealand doesn't consider environmental damage.
Allowing drilling to go ahead without seeing those documents breaches international laws relating to polluting the sea, it says.
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