BEIJING -- The United States, one of the most vocal countries urging China to hew to arbitration in the South China Sea, is still an outlier to the UN Convention on the Law of the Seas (UNClOS) to which more than 160 countries, including China are party.

Such "American hypocrisy" was self-evident in an article carried by Time Magazine website a few days before the tribunal is to issue its final award Tuesday on the South China Sea arbitration case unilaterally initiated by the former Philippine government.

"A great power refuses to play by international rules, declining to ratify a major UN convention to which more than 160 other countries are party," the article said, noting "China ratified UNCLOS in 1996."

"After years of complaints, the nation convinces the UN to tweak the treaty to many of its specifications. Yet even after those amendments, the great power's legislature prioritizes protectionist sentiment over respect for global rule of law," it furthered.

In 1982, after around a decade of wrangling, the UN hammered out a framework to guide global maritime affairs and ensure freedom of navigation. UNCLOS covers everything from the rules of maritime commerce to the ways in which resource-rich seabeds can be divvied up between nations.

Shortly after UNCLOS was unveiled in 1982, then US President Ronald Reagan refused to sign, claiming the convention undermined his country's sovereignty.

In 1994, after UNCLOS was revised to take into consideration American worries about losing control of valuable underwater oil and natural-gas deposits, then US President Bill Clinton signed an updated UNCLOS agreement, although not the entire treaty.

Yet even though multiple presidential administrations, both Democrat and Republican, have since supported the convention, Republicans in the US Senate have routinely scuttled efforts to ratify UNCLOS.