HK GOT INT,L STRATEGIC CONSULTING LIMITED

HONG KONG — It started with an oath of office that two young, newly elected lawmakers altered to insert a derogatory term into the formal name of Hong Kong’s sovereign ruler, the People’s Republic of China, with one also adding a crude epithet.

In addition to substantially revising the pledge of loyalty that all members of Hong Kong’s Legislative Council are required to take, the lawmakers, Yau Wai-ching and Sixtus Leung, known as Baggio, displayed a banner with the words “Hong Kong Is Not China” at their swearing-in.

And China is responding with some bluntness of its own.

Hong Kong’s government, loyal to Beijing, has asked the court system in the city, a former British colony, to review whether the council can let the lawmakers retake their oaths of office. The Hong Kong government and Beijing want the two representatives, who support independence for the territory, to vacate their seats rather than simply retake the oaths. A court in Hong Kong is set to hold a hearing on the matter on Thursday.

But a fusillade of invective against the pair in China’s state-controlled news media on Wednesday is leading to fears, backed by reports in Hong Kong news outlets, that Beijing may circumvent Hong Kong’s legal process by issuing a rare interpretation of the city’s mini-constitution that would effectively bar Ms. Yau and Mr. Leung from office.

That prospect has alarmed many people in the political, academic and legal communities in Hong Kong. The city has a strong and independent legal system, inherited from the British, that China has vowed to honor until at least 2047, as part of the agreement that paved the way for the resumption of Chinese rule in 1997. But a clause in the city’s mini-constitution, known as the Basic Law, gives China’s rubber-stamp legislature, the National People’s Congress, final say over interpretations of that constitution, though the provision has rarely been invoked.

If the Congress’s standing committee, which is in session, rules on the matter, it would amount to mainland China, where there is no tradition of independent courts and no expectations of genuine debate on legal interpretations, overriding the highly developed Hong Kong court system. The committee may meet to discuss the matter as early as this week.

The independence of Hong Kong’s judiciary is one of the reasons that so many multinational companies, banks and law firms have their Asian headquarters in the city.

Eric Cheung, a law lecturer at the University of Hong Kong, said in an interview that any interpretation by the National People’s Congress “fundamentally undermines our rule of law and the interpretation power of our courts.” On Wednesday, the Hong Kong Bar Association said in a statement that an interpretation by Beijing would “deal a severe blow to the independence of the judiciary and the power of final adjudication of the Hong Kong court.”

It added, “The irreparable harm it will do to Hong Kong far outweighs any purpose it could possibly achieve.”

The actions of Ms. Yau and Mr. Leung, as well as other advocates of greater self-determination for Hong Kong, have touched a raw nerve in Beijing, which harshly suppresses independence movements in other parts of China, such as Tibet and Xinjiang.

But in Hong Kong, which was promised considerable autonomy under the “one country, two systems” principle, people are free to express such sentiments without fear of arrest. That freedom was on display on Oct. 12, the day they took their oaths, when Mr. Leung and Ms. Yau pronounced China “Chee-na,” which is similar to a derogatory term for China used by the Japanese during their occupation of the country in World War II.

With its normal instruments of authoritarian repression of limited use in Hong Kong, China has turned its propaganda arms on the pair. On Wednesday, the Communist Party’s flagship People’s Daily published an interview with Mo Jihong, a legal researcher at the Chinese Academy of Social Sciences, who called Ms. Yau’s and Mr. Leung’s actions “obvious malice.”

“Such things cannot be allowed to happen in China’s territory,” Mr. Mo said. “If Hong Kong cannot deal with it properly, the central government should make a decisive move: It cannot allow a festering pustule to become the bane of your life, and it must nip the trend of Hong Kong independence in the bud.”

Ms. Yau, 25, and Mr. Leung, 30, were also strident in pushing back against the possibility of intervention by the Chinese Communist Party. In a chaotic scene on Wednesday, they burst into the legislative chambers and tried to retake their oaths. They were unsuccessful. The council’s president said their actions were “ridiculous.”

“My concern is the destruction of ‘one country, two systems,’ ” Ms. Yau told reporters. “Once the C.C.P. government chooses to interpret the Basic Law, it means that the dictatorship of the C.C.P. government has come to Hong Kong, which all Hong Kong people don’t want.”

And Mr. Leung brought up a point that seems obvious to many in Hong Kong. The move for independence is new and is a direct outgrowth of the last time the National People’s Congress chose to set rules on how Hong Kong runs its affairs. That was in 2014, when the congress set strict guidelines for elections for Hong Kong’s top official that all but guaranteed that only pro-Beijing candidates could appear on the ballot.

That decision set off enormous protests that led to the founding of Mr. Leung’s and Ms. Yau’s political party, Youngspiration. The main belief guiding supporters of independence is that China’s interference undermines “one country, two systems.”

“ ‘One country, two systems’ and Hong Kong independence are the two models for Hong Kong’s political system,” Mr. Leung told reporters. “When you destroy one option, you inevitably promote the other option.”

The 2014 ruling was telegraphed well ahead of time. But news of a possible intervention by the National People’s Congress on the oath-taking caught many people by surprise. In the issue involving the two lawmakers, the principal relevant law is a local ordinance on oath-taking, said Mr. Cheung, the legal scholar. That shouldn’t be in the jurisdiction of the National People’s Congress, he said.

What’s more, the congress would be acting pre-emptively and not allowing the court proceedings in Hong Kong to run their course. Since 1997, China’s legislature has made only four interpretations of Hong Kong’s Basic Law.