According to international law expert Professor Donald Rothwell of the Australian National University, evidence given by the whistleblowers to ABC's Foreign Correspondent program as to the commercial nature of Japan's whaling activities would be unusable in the International Court of Justice (ICJ).

"From a procedural perspective, the ICJ has significant limitations in terms of witnesses being called in the ways that we are familiar with in terms of domestic proceedings, so that is an immediate problem," he said.

"The court does allow experts to come and give evidence before it, but these people would not be experts ... It is very difficult to see any way in which Australia would be able to rely upon [it]."

The whistleblowers' allegations come at the same time two Japanese Greenpeace activists, known as the Tokyo Two, are being tried in a Japanese court for the theft of whale meat from a whaling vessel, the Nusshin Maru, in an attempt to show the media that whale meat is being packaged and sold.

But Rothwell again questions the utility of such evidence in aiding Australia's international legal bid.

"I don't really see that [evidence] being [useful] unless there is some sort of ruling by the Japanese court that these activities are commercial, and I doubt whether that sort of outcome would be anticipated," he said.

Rothwell added that any view that such evidence could assist Australia's case is simply "overstated".