@georgeob1,
Well, I believe that it is certainly worth a try. Whether the Australian government would win such a challenge or not, an international legal challenge would certainly attract a lot more attention to this issue.
Many here (you included) have commented disparagingly about the annual "whale wars" in the Southern Ocean, between the likes of Sea Shepherd & the factory whaling ships. Arguing that such publicity damages the anti-whaling "case". The thing is, Sea Shepherd has been the only active defender of whales each summer & has also kept the issue alive (say nothing of limiting the extent of the slaughter) via media reports.
An international legal challenge would add "respectability" to the anti-whaling case, for those folks who require such respectability before supporting a cause.
Me, I would really like the full details of the Japanese commercial whaling activities to be fully exposed in an international court of law. I believe, win or lose such a case, full disclosure of the details of the industry would persuade many people, currently "sitting on the fence" of the
rightness of the anti-whaling position.