Anti-whaling activist Pete Bethune says he believes Japan's whaling days may be over.
Japan has formally cancelled its next Antarctic whale hunt after the International Court of Justice, ruling on a case taken by Australia and supported by New Zealand, found that Japan's so-called scientific research programme failed to meet scientific conditions.
Mr Bethune, who spent five months in a Japanese jail in 2010 after a protest against whaling in the Southern Ocean, says the court's decision was emphatic and the judges really took Japan to task.
"The Japanese do not like losing like that," he says, "and I wouldn't be surprised if this causes a major rethink in Japan on their whaling programme."
Japanese prime minister Shinzo Abe says his country will abide by the ruling, although it plans to go ahead with scheduled research whaling in other areas, including the northern Pacific, AFP reports.
New Zealand Foreign Minister Murray McCully says the ruling could be used as a precedent against Japanese whaling in the northern Pacific.
Prime Minister John Key says it's too soon to say there won't be more whaling by the Japanese in the Southern Ocean. He says Japan will be taking stock of its position and nothing is guaranteed at the moment.
The next Antarctic hunt would have started in late 2014. Japan also has a coastal whaling programme that is not covered by the ban.