The Court of Appeal has reserved its decision on whether the Ministry of Primary Industries has been less than rigorous in controlling the export of rough-sawn swamp kauri.
In the High Court last year, the Northland Environmental Protection Society lost its claim that the ministry had allowed the Forests Act to be breached by permitting the export of swamp kauri stumps in an almost raw state.
The society challenged that decision in the Court of Appeal, arguing that stumps were being passed off as artworks and furniture, in breach of the Protected Objects Act and the Forests Act.
The society claimed that stumps, roots and slabs had often undergone only rudimentary embellishment to qualify as art or furniture.
It disputed that swamp kauri 'table tops', without legs or with light surface carving, could lawfully be exported.
Justice Toogood ruled in the High Court at Auckland last year that ancient swamp kauri was not subject to the Protected Objects Act, and its export could continue.
He said imposing extra restrictions would "create an oppressive regime restricting the removal from New Zealand, by ordinary travellers, of everyday products which have no particular significance".
He also refuted the society's argument that buried swamp kauri was a fossil worthy of protection under the act. He noted that there had been historical concern around the export of kauri stumps, but was satisfied with MPI's system, which he said had "progressively improved its procedures" since late 2011.