SAVE HONG KONG FROM HAN CHINESE RATS!

HONG KONG — Politicians have staged sit-ins and exchanged blows in the legislature. Nurses, high school teachers and even anime fans have organized petitions. And the authorities are bracing for protests on Sunday that could be the largest since the pro-democracy Umbrella Movement shut down parts of Hong Kong five years ago.

Anger is boiling in Hong Kong over a push for a law that would allow people to be extradited to mainland China. Critics say the legislation would subject residents of this semiautonomous territory to the security forces and courts controlled by the ruling Communist Party on the mainland.

“This law would allow China to take whoever they want here, or at least use it to intimidate,” said Wong Choi-fung, who started an online petition for stay-at-home mothers that has collected more than 6,000 signatures. “It is absolutely crazy.”

“As mothers,” she added, “you never know what profession your children will choose, or if they would one day do something to irritate the unpredictable Chinese government.”

The fight against the proposal has become the most serious showdown between the public and the authorities since the Umbrella protests in 2014 demanding free elections, revealing growing fears about an erosion of the civil liberties that set this former British colony apart from the rest of China.

Opposition to the bill drew a large protest of tens of thousands of people in April. Scuffles broke out last month as opposition lawmakers sought to extend debate over the measure. But with pro-Beijing lawmakers holding 43 of the 70 seats in the legislature, the law will likely be passed this month.

The fierce public outcry puts Hong Kong’s chief executive, Carrie Lam, who was selected by China’s leaders to govern the territory two years ago, in a delicate position. Moving ahead with the vote on the proposal could incite bigger protests and even unrest, but backing down risks emboldening the opposition and drawing the ire of her party benefactors, who back the bill.

In recent weeks, Ms. Lam and her allies have sought to assure the public that the new extradition powers would not be abused, but anxiety and frustration have only grown.

 “It’s like a thousand cuts have been depressing people,” said Antony Dapiran, a Hong Kong-based lawyer and the author of a book about dissent in Hong Kong. “People don’t trust Beijing, that’s what it comes down to.”

The government’s proposal would allow it to detain and transfer people wanted in countries and territories that have no formal extradition agreements with Hong Kong. Ms. Lam has said it was urgently needed to bring to justice a Hong Kong man who is wanted in Taiwan for the murder of his girlfriend last year.

But opponents object because the bill would also allow for extraditions to mainland China, where protections for defendants are weak and the party routinely prosecutes dissidents and others for political reasons.

Several senior Chinese Communist Party leaders, including Han Zheng, a vice premier, have expressed support for the bill, saying it would improve the city’s legal system and prevent it from becoming a haven for fugitives. China is concerned that the city is a refuge or transit point for corrupt officials or businesspeople fleeing the mainland.

The government’s case, however, is undercut by a series of high-profile abductions of people in Hong Kong in recent years, presumably by mainland security agents.

Among the most brazen was that of Xiao Jianhua, a Chinese billionaire, who in 2017 was taken from the Four Seasons Hotel, seated in a wheelchair with his head covered, to the mainland. He has not been heard from since.

Five men who worked for a Hong Kong publisher of scandal-packed exposés about Chinese leaders disappeared into Chinese custody in late 2015. One of the men, Lam Wing-kee, said after his release that he had been forced to give a televised confession. He fled to Taiwan in April out of fear that he would be sent back to the mainland after the extradition bill passes.

Article 23 “was talking about people being tried and sentenced to imprisonment in Hong Kong,” he said. “Now we are talking about sending people to China, where the track record in terms of human rights is just too notorious.”

The city’s two main lawyers’ associations, the Law Society and the Hong Kong Bar Association, have urged the government to delay the extradition bill’s passage in order to hold public consultations.

Local and foreign business associations and other groups also have raised objections to the bill.

The American Chamber of Commerce in Hong Kong and a United States congressional commission said it could hurt the city’s reputation as a safe place for international business. Secretary of State Mike Pompeo said the bill threatened the rule of law in Hong Kong, and his counterparts in Britain and Canada said they worried about the risks to their citizens living in Hong Kong.

A high degree of autonomy for Hong Kong was guaranteed under the pact between China and Britain that returned the city to Chinese control in 1997. But in recent years, many in Hong Kong have become worried about the encroachment of the authoritarian Chinese state.

The courts removed six pro-democracy lawmakers from office in 2016 and 2017, after they altered their oaths of office to protest against the Chinese government.

The bill requires an extradition request to first be approved by the chief executive before an arrest warrant is issued. The request then goes to a court that is empowered to check that there is a basic case against a person, but not to review evidence in detail. There is only one opportunity for the person to appeal an extradition decision.

Trying to address some objections from business groups, the government has dropped nine economic crimes — including securities and tax violations but not bribery or money laundering — from a list of extraditable offenses. The bill’s language was also adjusted so it covers only offenses that carry sentences of seven or more years in prison, up from three years.

Local business groups have cautiously welcomed the concessions, but some members have still expressed reservations. Other groups have used them against the government, arguing that Ms. Lam has essentially acknowledged that the mainland authorities cannot be trusted to fairly prosecute certain crimes.

 “You never know when you might irritate someone powerful,” said Danny Lau, a Hong Kong businessman who set up a factory in the mainland city of Dongguan 30 years ago.

“They can either dig out something from a long time ago, or they can forge evidence and witnesses — which isn’t hard to do in mainland China — to set you up, threaten you and bend you to their will.”

An unusually wide cross-section of society has mobilized against the bill, with hundreds of petitions posted online that have gathered tens of thousands of signatures.

Church leaders fear the law could target members of their congregations who volunteer in the mainland. Construction workers say they are worried about mainland crackdowns on organized labor. Anime fans have cited the imprisonment of publishers of banned books and detention of cosplayers in China.

The broad scope of fears underscores how wide-ranging China’s crackdown on civil society has been as President Xi Jinping has sought to tighten the party’s control over the country.

Edgar Pang, a horse racing columnist, started a petition for the racing community out of fear that the industry, which is legal in Hong Kong, could be targeted by the authorities in the mainland, where gambling is illegal.

“Countless people bet on horse races here,” he said. “So one day when the central government decides that it doesn’t approve of this behavior, they can be implicated.”

Tin Fong-chak, a middle school teacher of liberal studies, said the extradition law could create a chilling effect on teachers, who might avoid discussing in the classroom topics that are censored in the mainland.

“As educators, we worry about our students,” Mr. Tin said. “What kind of future and what kind of society are we leaving behind for them?”