The New Zealand Government has been told it will be able to support Australia in legal action against whaling.
The case is due to be heard at the International Court of Justice at The Hague, possibly in July.
Australia says Japanese whaling is in breach of its obligations under the International Convention for the Regulation of Whaling, as well as others seeking to preserve marine mammals and the marine environment.
New Zealand has been granted the right to take part.
Legal experts say New Zealand is not a party to the dispute, but is getting involved under the legal title of intervener.
This will involve making submissions to the court.
