Japanese whaling and Australian opposition to it has become as much a staple for the Australian media in summer as bushfires and the cricket. The level of interest has greatly intensified since Sea Shepherd Conservation Society entered the scene. Eschewing the restrained and peaceful protest tactics of Greenpeace, Sea Shepherd’s antics generate spectacular images of conflict.

The latest salvo in the “whale wars” took place on January 7. Three Australian anti-whaling activists boarded a Japanese whaling support vessel, the Shonan Maru No 2, in the Australian Exclusive Economic Zone off the coast of Western Australia.

The fate of the three men is uncertain: they may be taken to Japan to face criminal charges of trespass. This is a godsend story for journalists in an otherwise slow news period, who have been quick to pick up on an apparent “kidnapping” of Australian citizens protesting against taking “Australian whales” in “Australian waters”.

In reality, as is often the case, the legal situation is far more nuanced.

Australians kidnapped by Japanese whalers? Not according to the law

On Saturday, Sea Shepherd helped three members of the environment group Forest Rescue board the Shonan Maru 2 near the Western Australian coast. The night-time boarding was secretive, and there appears to have been no altercation with the Japanese crew. The men delivered a message reading: “Return us to shore in Australia and then remove yourself from our waters”. This action appears calculated to raise as many headaches for the Australian and Japanese government as possible.

The boarding took place in an area of waters where Australia’s Contiguous Zone (CZ) and Exclusive Economic Zone (EEZ) overlap. These are not “Australian waters” as has been contended by the opposition environment spokesman Greg Hunt.

In the CZ, which runs from the territorial sea out to 24 nautical miles, Australia can only police the customs, fiscal, immigration and quarantine laws that apply in Australian territory and Territorial Sea (which reaches to 12 nautical miles from the coast).

However Australian law does not apply in full and Australia does not have full jurisdiction or control over either the CZ or the EEZ. In the EEZ Australia can regulate fishing (and whaling), other resource activities (such as mining), and can take action to control pollution. But it cannot extend Australian law generally or exercise jurisdiction over foreign ships for any reason it pleases.

So long as it is not engaged in whaling, the Shonan Maru 2 is perfectly entitled to sail freely through the Australian EEZ, which for navigational purposes is high seas. Moreover, the Japanese master is entitled to detain the protesters and to deliver them to Japanese authorities to face a criminal charges under Japanese law.

Indeed this is precisely what happened in the case of the New Zealander Peter Bethune after he boarded the Shonan Maru 2 in the Southern Ocean in February 2010. He was held and taken to Japan where he was convicted of trespass and handed a suspended sentence by a Tokyo court. The same fate could await the trio of Forest Rescue protesters.

However, if the vessel steams south as planned to support the Japanese whaling fleet, it may be several months before the protesters will see dry land. It is questionable whether the Shonan Maru 2 is equipped to deal with prisoners for such an extended period.

The Australian government has asked that the men be returned to Australia promptly. If this occurs it seems unlikely that they will be able to be charged under federal or state criminal law.

The Attorney-General Nicola Roxon has commented that the incident occurred outside the Australian territorial sea and therefore there can be no automatic application of Australian law.

The only possible Australian law that may come into play is the Crimes (Ships and Fixed Platforms) Act 1992 (Cth) which applies extraterritorially to all persons and ships whatever their nationality. It implements a UN convention seeking to suppress maritime terrorism. But the boarding here was done peaceably and without endangering the vessel or its crew, so the legislation is almost certainly not enlivened.

This isn’t about “our waters” or “our whales”

Although sensational, the latest stunt by Sea Shepherd is a sideshow to the main game, which is the Australian government’s case against Japan in the International Court of Justice (ICJ). After considerable dithering by governments of both political persuasions, in May 2010 the Labor government commenced the ICJ case against Japan.

Whaling throughout the world’s oceans is regulated by the 1946 International Convention for the Regulation of Whaling. Originally a treaty designed to promote the whaling industry, in the 1980s it was radically changed with the adoption of the moratorium on commercial whaling.

This was accepted by Japan (after some initial protest), but shortly afterwards Japan began its very substantial research whaling programs in the North Atlantic and the Southern Ocean near Antarctica. Japan contends that these programs are fully legal because of Article VIII of the Whaling Convention, the so-called “scientific whaling loophole”, which allows the taking of whales for purposes of scientific research.

Australia makes four main arguments in its ICJ case:

• Japan has breached its obligation under para 10(e) of the Schedule to the Whaling Convention to observe in good faith the commercial whaling moratorium.

• Japan has violated its obligation under para 7(b) of the Schedule to act in good faith to refrain from commercial whaling for humpback and fin whales in the Southern Ocean Sanctuary.

• Japan has breached the obligation under Article VIII in relation to scientific whaling, “having regard to the scale of the JARPA II program, to the lack of any demonstrated relevance for the conservation and management of whale stocks, and to the risks presented to the targeted species and stocks”.

• Japan has breached the prohibition under 1973 Convention on the International Trade in Endangered Species on “introducing from the sea” of an Annex I listed species (in relation to humpbacks, but not minkes as Japan has lodged an objection for that species). The CITES prohibition means a state can’t transport any listed species it has taken from waters not covered by any state’s jurisdiction.

• Japan is not meeting its obligations under the 1992 Convention on Biological Diversity.

It is important to understand what this litigation is not about. It is not a contest about Australian sovereignty in Antarctica. In this respect comments by the opposition leader Tony Abbott that Australia should send a customs boat to Antarctica because “it’s important that Australia does what it reasonably can to exercise its sovereignty” are most unhelpful.

No Coalition or Labor government has ever sought to exercise jurisdiction over foreign nationals in the Australian Antarctic Territory or its waters because most states, including Japan, do not recognise Australian sovereignty.

Australia filed its detailed submissions in the case in May 2011, and in March 2012 Japan will submit its counter-memorial. We will then have to wait for the ICJ to set a date for the hearings, and then wait some more for a judgment.

Australia’s case is a strong one, but the result is far from predictable given the tendency for the ICJ to reach Solomonic decisions that seek to keep both parties equally happy (or unhappy). The slow-turning wheels of justice at the ICJ do not make for riveting reportage, but it is in The Hague and not the waters offshore Western Australia where the key legal issues in the “whale wars” are being played out.