On the first day of what was expected to be a two-day hearing, the EPS' lawyer, Davey Salmon, argued there had been a "massive increase in exports" of raw kauri and the ministry had ignored provisions in the 1949 Forest Act prohibiting the export. Whole or sawn stumps or roots may be exported with a milling statement and export approval but sawn logs from a trunk may not. Mr Salmon has asked the court to define the law's "exact limits".
Conservationists say extracting swamp kauri destroys wetlands and threatens the habitat of rare species.
Last year the EPS and Northland MP Winston Peters both called for a moratorium on the export trade. Other opponents say exporters are circumventing the ban by labelling kauri slabs as table tops or superficially carving slabs and calling them artworks or Maori carvings.
One Far North businessman, who did not want to be named, said large trucks laden with logs "running up and down State Highway 1" were a common sight and some local people believe there is "wholesale" export of unaltered kauri from several areas in Northland.