Two years ago, a standoff broke out between the Philippines and China, when Filipino authorities tried to arrest Chinese fishermen suspected of illegally fishing in the Scarborough Shoal.

China blocked the arrest, sending paramilitary vessels to surround the Philippine patrol ships. The face-off lasted two months before the US intervened, securing assurances from both sides to withdraw vessels from the disputed rock formation in the South China Sea. The Philippines left. China ignored the deal and stayed.

After months of diplomatic wrangling, the Philippines filed a lawsuit on Sunday, challenging China before a UN court at The Hague. The case questions the validity of China's "nine-dash line" claim (refering to the line that China puts on maps to justify its claim) and its occupation of Scarborough. The Philippines argues that the U-shaped boundary, which China set out based on "historical rights", encroaches on its territory under international law.

There's a lot of political tension and hostility that make cooperation very, very difficult. - Bonnie Glaser, Center for Strategic and International Studies, Washington DC

"It is about defending what is legitimately ours," Albert del Rosario, the Philippine foreign minister, told reporters on Sunday. "It is about securing our children's future. It is about guaranteeing freedom of navigation for all nations. It is about helping to preserve regional peace, security and stability."

What China claimed as part of its "indisputable sovereignty" covers almost 90 percent of the South China Sea. It also overlaps the areas claimed by other countries, including the Philippines, Vietnam, Malaysia, Brunei and Indonesia.

On Saturday, the Chinese coastguard attempted to block a Philippine naval vessel from delivering supplies to a marooned ship in the Second Thomas Shoal. The Chinese warned the vessel to turn around but were ignored. It was the second incident between the two countries in two weeks in the Spratlys, south of Scarborough.

To maintain order in the region, countries must abide by the UN Convention on the Law of the SEA (UNCLOS), senior justice Antonio Carpio said in a speech in Manila. But, he said, China has disregarded the law which is considered to be the world's constitution on the seas and oceans.

"China is enforcing its claim through its rapidly growing naval fleet," he said. "If left to stand, China's claim will bring the world back to the turbulent maritime era of 400 years ago, when nations claimed the oceans and seas through the naval cannon, not through the rule of law."

'Historical rights'

Under UNCLOS, which both China and the Philippines ratified, coastal states like the Philippines are entitled to a 322km exclusive economic zone (EEZ). Beyond that is considered the high seas, common to all nations. Scarborough is 220km from the Philippine mainland of Luzon, and 857km from China's Hainan province.

China claimed that its sailors discovered Scarborough 2,000 years ago, and had fished in the region as far back as the Song Dynasty from 960 to 1279 AD. China refers to it as Huangyan Island, while the Philippines calls it Panatag.

In a foreign policy discussion at the University of Southern California, Chinese scholar Shen Dingli also reiterated China's historical claim over Scarborough and other islands in the region.

"For China, we say our ancestors used to occupy these islands," he said. "So I have this book to show. Look, and my fishermen used to use the islands to avoid the typhoons. It’s all recorded.

"So we consider that a thousand years ago, these people already used this sea lane of communication for China’s interests. Therefore, the ancestors of them have the right to claim."

Al Jazeera tried to contact the Chinese Embassy in Manila for comment, but did not receive a reply. In a statement reported by the state-owned news agency Xinhua, Chinese Foreign Minister Wang Yi recently said: "China has sufficient historical and legal evidence for its sovereignty over the Nansha [Spratlys] islands", and other islands and adjacent waters across the South China Sea.

Wang blamed the dispute on "some countries' illegal occupation" of islands belonging to China since the 1970s.

"Even so, China has always been committed to solving disputes through negotiating directly with countries involved and in a peaceful manner," the foreign minister told Xinhua.

He said that recent "unfounded and untrue rumours" had magnified disputes in the South China Sea and "artificially upped tensions in the region".

Carpio, however, said there is no UNCLOS provision that grants China "historical rights" over vast parts of the resource-rich section of the Pacific Ocean.

Chinese foreign ministry spokesman Hong Lei has said that China will not participate in the arbitration proceedings. But experts say that the tribunal will likely give China six months to answer the case.

'David vs Goliath'

China's action in Scarborough leaves the Philippines with no other recourse but to bring the case to the international tribunal, said Bonnie Glaser, an expert on China and Asia-Pacific at the Center for Strategic and International Studies in Washington DC.

"After the whole Scarborough Shoal incident, it just became clear that the Philippines was not going to be able to defend its rights by itself," she said. "In fact, it could not even rely on the United States. Because at the end of the day, the US did nothing to prevent China from taking over Scarborough Shoal."

She dismissed China's proposal for "bilateral consultations and negotiations" to the dispute, saying it will only benefit China more than the Philippines. Up to the last minute, China had been urging the Philippines to postpone the filing of the case.

"There's a lot of political tension and hostility that make cooperation very, very difficult," Glaser told Al Jazeera.

The Philippines has also learned from its recent history. In 1995, China occupied Mischief Reef, which is also within the Philippines' EEZ. China never left the reef despite Manila's repeated diplomatic protests.

"The only way to really resolve this is going to be through the use of international arbitration," Glaser said. "I don't think bilateral, or multilateral negotiations are going to lead to a resolution."

But Jay Batongbacal, an international maritime law expert and law professor at the University of the Philippines, said that there have been cases before international tribunals where opposing parties reached a settlement. He cited the case between Singapore and Malaysia over the reclamation in the Strait of Johore, which was dismissed before adjudication following a settlement.

As for the relationship between the Philippines and China, Batongbacal said that despite previous disputes, trade between the two countries flourished.

"Unfortunately, it appears that this policy no longer holds true after the Scarborough Shoal standoff in 2012," he told Al Jazeera.

He said that it would take an "enormous amount of skilled statesmanship" on both sides to repair relations adding that both countries "have gone to real extremes, leaving little room for flexibility and compromise".

One of the main reasons why China's leaders are maintaining a hardline stance in South China Sea is domestic politics, Glaser said.

"Compromise that is seen by the public as making concessions to other countries, and weakening the nation, could lead to criticism of the Communist Party and the legitimacy of the party. Of course keeping the regime in power is really the number one priority."

Batongbacal likened the current standoff between the Philippines and China to the battle between David and Goliath.

"Not only in the sense that it is a small country doing battle against the large country, but also in the sense that the Philippines must hit the Chinese legal armour at exactly the right spot in order for it to prevail," he said.