The Philippines argued at a closed hearing Tuesday that an international court should intervene in its dispute with China over rights to exploit natural resources and fish in the South China Sea.
Though China has declined to participate, the case at the Permanent Court of Arbitration in The Hague is being closely watched by other Asian governments and Washington, given rising regional tensions as Chinese naval power grows.
A panel of five judges will hear arguments this week and decide whether the treaty-based court has jurisdiction.
China has laid claim to nearly all the South China Sea, while the Philippines, Vietnam, Malaysia, Taiwan and Brunei claim overlapping parts of it.
Manila filed suit at the court in 2013, seeking to enforce its right to exploit waters in a 200-nautical mile exclusive economic zone off its coast, as defined under the U.N. Convention on the Law of the Sea.
The Philippines argues that the arbitration court is the correct venue for resolving disputes covered by the treaty, which both countries have signed. "The Philippines believes the court has jurisdiction over all the claims it has made," said lawyer Paul Reichler, representing the Philippines.
He said he is "confident" the court will ultimately rule in the Philippines' favor.
Chinese Foreign Ministry spokeswoman Hua Chunying said China doesn't accept the court's jurisdiction and will not participate. "China opposes any form of arbitration process proposed and promoted by the Philippines," she told a daily news briefing in Beijing.
In a position paper in December, China argued the dispute is not covered by the treaty because it is ultimately a matter of sovereignty, not exploitation rights.
Manila says Beijing is unfairly preventing it from accessing reefs and shoals that are under its dominion.
Reichler said the case can continue even if China declines to participate. The court's rulings are binding, though it has no power to enforce them, and countries have ignored them in the past. He declined to discuss the details of the Philippines' arguments on Tuesday, saying doing so might aggravate the judges.
Court legal counsel Judith Levine said the court would not comment on the proceedings beyond a brief statement saying proceedings have begun.
Reichler expects a decision on jurisdiction within 90 days. A ruling on the merits of the case could take years.