The crowds wanted the city's pro-Beijing leaders to scrap the proposals but there is little sign of that happening, and the issue has plunged the city into a political crisis.
Hong Kong witnessed its largest protest since the city's 1997 handover to China on Sunday as hundreds of thousands came out to oppose plans to allow extraditions to the mainland.
The crowds wanted the city's pro-Beijing leaders to scrap the proposals -- but there is little sign of that happening, and the issue has plunged the city into a political crisis.
The city's government is pushing a bill through the legislature that would allow extraditions to any jurisdiction with which it does not already have a treaty -- including mainland China.
They say it is needed to plug existing loopholes and prevent the city from becoming a bolthole for fugitives.
Hong Kong leader Carrie Lam says safeguards are in place to protect the city's free speech, and to ensure political cases will not be affected by the extradition law.
She also argues that the law meets international standards for human rights, and that only serious crimes that carry sentences above seven years will be considered.
Fears centre on getting tangled up in China's opaque and politicised courts -- whether it be the city's 7.3 million inhabitants or those just passing through the airport.
A broad cross-section of society has opposed the legislation, including lawyers and influential legal bodies, business figures and chambers of commerce, journalists, activists and western envoys.
Then on Sunday some one million people marched against the bill, according to organisers, in unprecedented scenes.
Hong Kong's appointed leaders are increasingly perceived to be doing the bidding of Beijing, and there is little trust in their assurances that the law won't impact the city's prized independent judiciary or its wider freedoms.
Jimmy Sham, convenor of the group behind Sunday's protests, said young people felt "powerless" in the face of a "brutal" government.
Yes. But under the 1997 handover agreement with Britain, China has agreed to a 50-year deal where Hong Kong is able to retain key liberties, such as freedom of speech and an independent judiciary.
The city's courts and rule of law, built around the British legal system, are key to the financial hub's economic success.
The idea of Hong Kong being a bolthole for fugitives had never been high up the political agenda. But after a Hong Kong man murdered his girlfriend while on holiday in Taiwan and fled back home, local authorities seized on the case to call for an overhaul of the law.
Despite confessing to Hong Kong police, authorities were unable to extradite him because the two territories do not share an agreement.
The extradition law was born, covering any place Hong Kong doesn't have a specific agreement with -- including mainland China for the first time.
But critics say the Taiwanese case is a Trojan horse to please Beijing.
Certainly. Outside of Hong Kong's local government, the bill has received public backing from senior party officials in China and state media.
A petition run by a group that supports the bill has collected more than 800,000 signatures, while the Hong Kong government has a comfortable majority of lawmakers who have say they will back the bill.
But proponents have not managed to get people onto the streets in anything like the numbers seen in Sunday's opposition protest, making it hard to gauge genuine public support.
There are no signs of tension diffusing. On Monday Carrie Lam refused to delay or scrap the extradition bill and said her administration had already made major concessions to protect human rights.
Hong Kong police said they will track down protestors behind violence in the early hours of Monday morning.
But opponents of the law have also doubled down, announcing plans for fresh protests on Wednesday alongside calls for a city-wide strike.
And Beijing has added its own rhetoric to the mix, attacking "foreign forces" for trying to disrupt a "sensible, legitimate" piece of legislation.