The leading court at the UN will rule on Monday on whether Japan has the right to hunt whales in the Antarctic, an emotive case that activists say is make-or-break for the mammals' future.
Australia took Japan to the international court of justice (ICJ) in The Hague in 2010, accusing Tokyo of exploiting a loophole by hunting whales as scientific research to get around a 1986 ban on commercial whaling.
Australia has asked the ICJ to order Japan to stop its Jarpa II research programme and "revoke any authorisations, permits or licences" to hunt whales in the Southern Ocean.
During hearings last year, Canberra accused Tokyo of doing nothing more than "cloaking commercial whaling in a labcoat of science".
Norway and Iceland maintain commercial whaling programmes in spite of the 1986 International Whaling Commission (IWC) moratorium, but Japan insists its programme is scientific, while admitting that the resulting meat ends up on plates back at home.
Japan has killed more than 10,000 whales under the programme since 1988, according to Canberra, allegedly putting it in breach of international conventions and its obligation to preserve marine mammals and their environment.
In its application to the ICJ, Australia accused Japan of failing to "observe in good faith the zero catch limit in relation to the killing of whales".
Japanese officials declined to comment on specifics ahead of the ruling, but a fisheries agency official said it maintained the view that "Japan's whaling is purely for the purposes of obtaining scientific data, so that whale resources can be sustainably maintained".
Tokyo has consistently defended the practice of eating whalemeat as a culinary tradition. Its lawyers have said the Japanese have a "proud tradition of living in harmony with nature, and utilising living resources while respecting sustainability".
The country's fisheries minister, Yoshimasa Hayashi, vowed last year that Japan would never stop its "long tradition and culture" of whaling.
Japanese officials have said Tokyo will accept the verdict from the ICJ, set up after the second world war to rule in disputes between countries.
Australia also said it would respect the ruling, but added that its views were clear. "We oppose all commercial whaling, including Japan's so-called 'scientific' whaling."
In April last year, Japan announced its whaling haul from the Southern Ocean was at a record low because of "unforgivable sabotage" by activists from the Sea Shepherd environmental group.
Sea Shepherd has called the ICJ case make-or-break for whales in the Southern Ocean.
"We are still preparing to head down regardless [of the ICJ's decision]," said Jeff Hansen, the organisation's director. Sea Shepherd spends about £2.4m annually on its anti-whaling campaigns.
John Frizell of Greenpeace said a decision in favour of Australia "would place Japan in a very difficult position and present great difficulties for its operation in the Antarctic".
If the court rules in Japan's favour, however, "they will feel vindicated and free to continue their operations, which are becoming increasingly controversial", he said.
