Day 1: PH begins arguments in The Hague

Metro Manila (CNN Philippines) — The Philippines has begun arguing before the Permanent Court of Arbitration in The Hague that the treaty-based court has jurisdiction — and should intervene — in the country's dispute with China over the West Philippine Sea.

Malacañan said the first day of hearings began with Solicitor General Florin Hilbay's introduction of the Philippines' case, and his presentation of the order of speakers.

Foreign Affairs Secretary Albert del Rosario made a plea for the tribunal to recognize its jurisdiction. He noted that the case is important not just to the country but also to the global community, owing to its impact on the rule of law in maritime disputes.

Related: The Hague arguments: Philippine case against China explained

Paul Reichler, chief counsel of the Philippines, presented the justification for the five-man tribunal's jurisdiction over the Philippine claims under the United Nations Convention on the Law of the Sea (UNCLOS).

Reichler was followed by Philippe Sands, who explained that the Philippines did not raise questions of sovereignty over land or maritime delimitation.

Sands is the director of the University College London's Centre on International Courts and Tribunals.

The first round of Philippine arguments will continue Monday (July 8) with two more hearings, from 4 p.m. to 7 p.m. and 8:30 p.m. to 11:30 p.m., Philippine time.

A few hours before the hearing, Undersecretary Abigail Valte, deputy presidential spokesperson, told CNN Philippines that the delegation is cautiously optimistic that the tribunal would rule in favor of Philippine' on the jurisdiction issue.

Read: 'We're ready,' says Valte on West Philippine Sea case

Valte is also in The Hague with the Philippine delegation.

"We have been preparing every day, every step of the way to come to a proceeding like this," she said.

China has refused to take part in the proceedings. It prefers to conduct bilateral talks with the Philippines.