The Philippines' move to seek a ruling from a UN arbitration tribunal over China's so-called nine-dash line represents a dramatic throw of the political and legal dice. It is anyone's guess where they will land.
The line represents China's historic claims to virtually all of the South China Sea, reaching deep into the heart of maritime South East Asia and bisecting the economic zones of several nations, including the Philippines, Vietnam and Malaysia.
Manila's step - launched without China's consent - is unusual and highly technical, according to international lawyers. Even officials in Manila noted it could take as long as four years - a period during which they are braced to suffer China's diplomatic wrath.
"We are all for improving our economic relations with China but it should not be at the expense of surrendering our national sovereignty," a Philippine statement said yesterday.
And, of course, there is no guarantee of success - or even a certainty that a tribunal set up under the UN's Convention on the Law of the Sea would agree to hear the case.
Victory, however, would potentially crack open the nine-dash line to fresh challenge. Such a tribunal ruling would be legally binding and carry international moral weight, lawyers said, but would offer no enforceable solution. And in the current atmosphere, with Manila initiating the move over Beijing's private and public objections to any "internationalisation" of the dispute, it is hard to imagine China feeling restrained by any such ruling, observers noted.
"The political considerations can be far greater than the legal issues in these kind of cases," said one US-based lawyer with experience in Law of the Sea disputes. "It is a pretty big step to take a sovereign state to arbitration against its will."
The fact that the Philippines can contest China's actions and positions without Beijing's consent represents a unique feature of the UNCLOS compared with other UN conventions. Unlike the International Court of Justice - already rejected by Beijing as an option to solve the South China Sea disagreement - a tribunal cannot be used to settle issues of sovereignty, but it can deal with a range of related disputes.
China signed up to UNCLOS in 1994 and exempted itself from dispute action in certain areas, including military activities and historic waters. But, legal scholars warned, there remained plenty of wiggle room. Unilateral action would still be possible concerning fishing rights in another country's economic zone, or whether a disputed rock or reef could be considered an island, and therefore entitled to an economic zone.
That puts the dispute over the Scarborough Shoal, known as Huangyan in Chinese, and the contested rights of Chinese fishermen potentially in the frame, as it is a relatively small feature sitting within the Philippines-claimed 200-nautical mile exclusive economic zone - the basis for a possible challenge to the controversial nine-dash line.
For all the risks, officials in Manila have not moved rashly. Under the guidance of Foreign Affairs Secretary Albert del Rosario, scholars and lawyers have for months been formulating a strategy. They have also engaged a leading Washington lawyer, Paul Reichler of Foley Hoag.
Officials in Beijing said they had been building up expertise and experience in the UN convention and its tribunals.
"We are not afraid of UNCLOS," one Chinese diplomat said recently. "Manila underestimates our knowledge at its peril."