Judge Lowell Goddard said that Dow's application was "very late". He added that Dow wanted to submit scientific analysis, but this was outside the scope of the case - the High Court was only considering whether the technology fitted the legal definition of genetic modification.
Crown forestry research institute Scion made the initial application to have the technique, known as zinc finger nuclease or ZNF-1, exempted from New Zealand laws governing genetic modification. The institute has said that the technique mimicked nature, and described it as "an alternative approach to creating mutant lines".
The Environmental Protection Agency (EPA) approved the application, though its staff had originally advised that the high degree of manipulation involved in the technique meant it should not be exempted from GM rules.
The exemption meant that it could be released or planted without notification, assessment or monitoring. Its use was suspended until the case was resolved.
The Sustainability Council said it believed that the EPA had misinterpreted the law.
"If the decision is allowed to stand, New Zealand could lose its GM free food producer status overnight without having assessed what is at stake. The ruling could also pave the way for other new GM techniques to bypass New Zealand's hard-won public protections."
In granting the approval, the EPA said that its decision highlighted the need for a review of the GM regulations, which were "not keeping pace with a rapidly evolving field of science".
WHAT IS THE CASE ABOUT?
An environmental trust, the Sustainability Council, is appealing a decision by the Environmental Protection Authority to exempt a new DNA-editing technique from GM rules. The council believes the technique qualifies as genetic modification.
WHAT IS THE NEW TECHNIQUE?
Known as zinc finger nuclease, or ZNF-1, it is used to break DNA strands to allow insertions or deletions. This allowed scientists to manipulate plant or animal genomes to make them work in different ways.
HOW IS IT USED?
Separate studies have used DNA editing to treat mice with the blood disorder haemophilia and HIV. In future, doctors could be able to remove faulty genes in humans and replace them with healthy versions.