Japan has claimed a clear and indisputable legal right to determine alone how it will conduct its Antarctic scientific whaling, at the International Court of Justice.
Whatever sympathy might be felt for whales, the global treaty on whaling had a crucial proviso that it was up to each member government to grant their citizens special scientific permits to take whales, Japan's counsel Alain Pellet said.
"The terms of article eight (of the International Convention for the Regulation of Whaling) are unambiguous," said Professor Pellet, of the University of Paris Oeust.
"The decision-making power rests with the state party concerned," he said. "Not to be a subject of multi-lateral decision-making...This is a discretionary power that article eight grants to state parties."
Professor Pellet was responding in The Hague to Australia's plea for the ICJ to halt the program, as disguised commercial whaling that has killed more than 10,000 whales.
Japan replied this week alleging that Australia was on an alarmist crusade intended to impose Australian cultural preferences over the Japanese.
On Wednesday the Japanese legal team moved to broaden its defence before the court.
Professor Shotaro Hamamoto described the current Japanese program, known as JARPA II, as the most comprehensive research program ever carried out on whales and the Antarctic ecosystem.
It had concrete research objectives, and gained support from the International Whaling Commission's scientific committee, particularly in a 1997 review, said Professor Hamamoto, of Kyoto University.
"Australia argues JARPA II focusses disproportionately on lethal methods.," he said. "Quite to the contrary, JARPA II employs non-lethal methods quite extensively to obtain the best possible information."
According to Professor Alan Boyle of Edinburgh University, the ICRW's clear purpose was to promote the sustainable use of whales.
"Conservation of whale stocks...has always implied and continues to imply the sustainable use of whales including their use for scientific purposes," Professor Boyle said. "And not their protection from any use whatsoever.
"Far from its true purpose being the continuation of commercial whaling, JARPA II provides information related to the conservation and management of whale stocks."
Professor Boyle moved to discredit the Australian case before a panel of 16 international judges, saying it could offer the court no cogent or credible basis for its arguments.
Instead he said it was "confused and illogical, out of touch with contemporary international law."
As proceedings paused, one of the judges asked on notice what appeared to be a threshold question of Australia.
India's judge Dalveer Bhandari said: "what injury if any has Australia suffered as a result of Japan's alleged breaches of the ICRW through JARPA II?"
The case is continuing.