On first blush, the proposed legislation that sent more than a million Hong Kong residents into the streets last week and resulted in violent clashes with police may not seem like such a big deal. Its purpose is purportedly to allow the accused murderer of a Hong Kong girl to be extradited to Taiwan, where the killing is alleged to have occurred.

But the protesters know that the bill is actually the latest attempt by China’s central government to further breach Hong Kong’s autonomy and the essential human freedoms guaranteed by treaty until at least 2047.

The extradition bill would permit the Beijing-controlled Hong Kong authorities to send residents for trial to any country. The problem is that those countries include China, where Hong Kong residents would be at the mercy of a system controlled by a government unencumbered by civil rights protections, by checks and balances or by a transparent system of justice.

Hong Kong protesters are facing an intolerable crackdown that would have seemed unhappily familiar to American colonists contemplating revolution against the British king in the 18th century. Just as the Americans were used to governing themselves notwithstanding their formal relationship with a distant country, and just as they were properly outraged when that country began to crack down on perceived troublemakers by transporting them “beyond Seas to be tried for pretended offences,” as the Declaration of Independence puts it; so the people of Hong Kong are facing the destruction of their accustomed freedoms by a Chinese government that only reluctantly acknowledges the autonomy of its “special administrative region.”

It is a coarse and bullying move. Beijing controls the levers of power in Hong Kong but has to an extent abided by the 1997 treaty with Britain that transferred the territory to China while promising a continuation of a capitalist economic system, independent courts and freedoms of speech and assembly for 50 years. The “one country, two systems” notion has provided international investors and companies an important base for doing business in China without subjecting themselves to random or oppressive Chinese justice. In recent years, though, China has begun to chip away at Hong Kong’s freedoms. The extradition bill would further chill confidence in China.

A disapproving world’s options are few. Nations have expressed their unhappiness over the oppression of China’s Uighur population and its treatment of Tibet, but are loath to impair trade relations. The U.S. is already locked in a trade war with China, and the Hong Kong situation only drives the countries further apart. Furthermore, it’s hard to see how extending tariffs to exports from Hong Kong, which are not currently covered, would do its people any good.

Yet it’s essential for the U.S. and other nations of the world to press Hong Kong’s case. And it is essential to behave as if China — which purports to respect treaties, if not human rights — just might listen.