To protest against a proposed extradition law.

That would allow the mainland Chinese government to ask for people it accuses of various crimes to be sent back from Hong Kong to mainland China.

Now these protests, if that 1 million figure is accurate, would be by far the largest protests that we've seen in Hong Kong since the former British colony was handed back to China in 1997.

Protests went on until the early hours of Monday morning.

And around midnight, amidst claims of police heavy-handedness, there were some violent clashes.

Several people were arrested.

The scale of these protests shows just how little faith many people here in Hong Kong have in the mainland political and legal system.

It also shows how worried people are about the proposed clauses in this law.

That would allow people not only living in Hong Kong but also just passing through Hong Kong to potentially be sent back to the mainland if they're accused of a whole range of different crimes.

What's also interesting about these protests and the clash over this particular law, this extradition law is that:

Many business organisations, including many foreign business organisations, are deeply opposed to it.

They feel there's potential for this law to be used to persecute people involved in business disputes.

Or people who are speaking out against maybe economic policy in Beijing to be persecuted.

Which is what we sometimes see in the mainland Chinese political and legal system.

Chinese President Xi Jinping has shown that he has no intention to back down in the face of popular unrest and popular disapproval.

So more than likely what we will see is that this law will pass and things will continue to deteriorate here in Hong Kong.