Hundreds of thousands of people took to the streets in Hong Kong on Sunday to oppose amendments to an extradition law that could be passed in coming weeks. The proposed law would allow authorities to send anyone who sets foot in Hong Kong to mainland China for trial for certain alleged offenses.

What is the extradition law?

The Hong Kong government proposed amendments to its extradition agreements in February, saying the proposal was spurred by a case of a man who allegedly murdered his girlfriend in Taiwan and fled back to Hong Kong. Because Hong Kong doesn’t have an extradition treaty with Taiwan, a self-governed island off China over which Beijing claims sovereignty, neither jurisdiction has been able to bring the man to trial for the murder. The law would allow China to extradite suspects from jurisdictions with which it doesn’t have treaties. Hong Kong, which retains a common-law system from its time as a British colony, has extradition agreements with more than a dozen countries, including the U.S., U.K. and Singapore.

Why is it controversial?

When Hong Kong was handed back to China in 1997, Beijing guaranteed to uphold people’s freedoms and the city’s legal system until at least 2047 under the concept of “one country, two systems.” Since the 79-day “Umbrella Movement” pro-democracy protests in 2014 failed to extract concessions from the government, there have been signs that authorities are increasingly intolerant of dissent: They have jailed activists for their role in the protests, banned a pro-independence political party and effectively expelled a foreign journalist for hosting a talk from the founder of that party.

Why are so many people in Hong Kong protesting?

Citizens have reacted strongly to the extradition amendments, which critics say would subject every person in Hong Kong to the mainland’s judicial system, leaving them subject to arbitrary detention and torture.

Why is the government ignoring them?

The government has stressed that if the amendments aren’t passed as soon as possible, Hong Kong residents’ safety will be at risk and the city would “continue to be a bolt-hole for criminals.” It said that the new law would only apply to serious crimes punishable by imprisonment of seven years or more, and that the crimes must exist in the laws of both Hong Kong and China before a surrender request would be processed. Furthermore, officials say, no offenses liable to extradition relate to the freedom of assembly or free speech.