The world has been riveted by the protests raging in Hong Kong against the city government’s proposed law to allow the extradition of criminal suspects to mainland China. About one million people—roughly one-seventh of the former British colony’s population—took to the streets on 9 June to denounce the draft law, and another large protest on 12 June resulted in violent clashes between demonstrators and police.

Yet, despite the massive protests, the Chinese government is determined to get its way. Instead of withdrawing the proposed law, Hong Kong’s Beijing-controlled leaders have fast-tracked the bill and scheduled it for a vote in the city’s legislative council at the end of this month. Its adoption would be a calamity not only for Hong Kong, but also for China.

The proposed extradition law would violate China’s pledge to adhere to the model of ‘one country, two systems’ in Hong Kong. And by giving the authorities in Beijing a convenient legal tool to grab individuals deemed to be ‘enemies’ of the Chinese state, the legislation would imperil the liberty of Hong Kong’s citizens—and of foreigners residing there.

Although the draft law doesn’t formally apply to political offences, this will offer no protection in practice. Under the Chinese legal system—which is controlled by the Chinese Communist Party—the distinction between political offences and conventional crimes is hopelessly blurred. Increasingly, in fact, the Chinese party-state persecutes human-rights activists by accusing them of criminal, not political, offences. Common charges include ‘running an illegal business’ and ‘picking quarrels and provoking trouble’.

If the proposed law is adopted, the mainland authorities will be able to arrest anyone in Hong Kong easily, by charging the target with an extraditable crime. Given the low threshold of proof—prosecutors would not need to provide evidence beyond probable cause—the protection against politically motivated extradition requests is frighteningly slim.

At the same time, however, China’s leaders should be aware that the outside world is watching these developments with great alarm. Unless the Chinese government backs down, the United States, in particular, will most likely take steps to make it pay dearly.

Since Hong Kong returned to Chinese rule in 1997, Western governments have maintained special economic privileges to help bolster confidence in the city. In 1992, the US Congress passed the US–Hong Kong Policy Act, in order to continue treating the city as a separate entity from mainland China. The law grants Hong Kong economic and trading privileges, such as continued access to sensitive technologies and the free exchange of the US dollar with the Hong Kong dollar.

But such benefits are contingent upon China fulfilling its commitments under the 1984 Sino-British Joint Declaration on Hong Kong, which set out the terms of the city’s future handover. Among other things, China pledged to maintain Hong Kong’s high degree of autonomy, freedom and rule of law for 50 years.

The US–Hong Kong Policy Act has teeth to deter China from violating its commitments. In particular, it explicitly empowers the US president to issue an executive order suspending some or all of Hong Kong’s privileges if he or she determines that ‘Hong Kong is not sufficiently autonomous to justify treatment under a particular law of the United States’. In making such a determination, the president should consider ‘the terms, obligations, and expectations expressed in the Joint Declaration with respect to Hong Kong’.

Even a cursory reading of the act should make it clear to China’s leaders that their actions in recent years have already seriously jeopardised the city’s status as an autonomous entity. Such actions include the abduction of five Hong Kong–based book publishers, the disqualification on dubious grounds of democratically elected city legislators and the imprisonment of pro-democracy activists. For the US, the passage of the extradition law could well be the last straw.

The unfolding confrontation between China’s leaders and Hong Kong’s citizens will provide fresh ammunition to US hardliners who have been advocating an aggressive stance against the Chinese government. Revoking Hong Kong’s privileges would advance that goal, because it would significantly hurt China.

After all, as the Sino-American economic cold war escalates, and rising regulatory and legislative hurdles make it harder for Chinese companies to raise capital in the US, Hong Kong will become immensely valuable to China as an offshore financial center. But if the US decides to withdraw Hong Kong’s privileges on the grounds that Chinese actions no longer justify treating it as a separate entity, the city’s value as a financial center will be fatally impaired. China’s companies will have less access to capital, and the valuations of Chinese state-owned enterprises listed on Hong Kong’s stock exchange will fall.

Even if the US doesn’t take this punitive step, China will reap what it has sowed. The likely passage of the extradition law will irrevocably tarnish the rule of law in Hong Kong and its attractiveness as an international commercial hub. Unless China’s leaders are prepared to accept these disastrous consequences, they should withdraw the bill before it’s too late.