The country's highest court has refused to hear a bid to restrict research on the genetic modification of animals.
The Supreme Court has ruled the case brought by lobby group GE-Free New Zealand had little chance of success.
AgResearch wants to expand experiments with animals modified to produce human proteins in their milk.
Last year, the High Court said the Environmental Risk Management Authority was wrong to accept the crown research institute's application for the research. The Court of Appeal reversed that decision three months ago.
GE-Free New Zealand wanted to go to the Supreme Court to try to stop the research, but the court has turned down the application.