"When I sleep at night what happened to me comes back to me. I have nightmares," Jimmy, as we've agreed to call him, said.

Jimmy is currently on bail and is unsure if he will be charged with unlawful assembly and contravening the mask law when he is next summoned.

The maximum penalty for unlawful assembly in Hong Kong is three to five years in jail, while wearing a mask is punishable by up to a year in prison.

Juveniles given a custodial sentence are likely to serve it in a rehabilitation or youth detention centre.

"I'm worried about what will happen now. I'm worried that the judge will treat me unjustly," he said.

Jimmy and kids like him now rely on a network of support services including legal advice, which is often provided pro-bono.

Lawyers come to the rescue as teens face jail time
Sally Wong, a 26-year-old barrister, is part of a group of lawyers providing free support for young people who have been arrested in the course of the protests.

"I see that there are many young people, like 13 or 14, and I think it's quite sad to see them charged with such serious offences," she said.

For Ms Wong and a network of lawyers, supporting children facing custodial sentences is a big job.

Approximately 5,800 people have been arrested in Hong Kong in the past six months, and more than 900 of them have been charged.

During the recent siege of the Polytechnic University, Sally Wong and her colleagues worked around the clock for several days, going to the police station, and then briefing and advising those arrested and detained.

At bail hearings, large groups detained at the same time and for the same charge are being processed through the court system in batches.

In one hearing the ABC attended, 15 young people charged with rioting had their bail extended, as did 11 others, including several under the age of 18, charged with unlawful assembly.

Among them was a 17-year-old girl whose parents and brother came to court with her.

Her father, who wants to be known only as Terence, said he had warned his daughter the day she went to the protest not to get into any trouble.

"[I said] 'Don't do any violence, don't … attack the police or damage any facilities,'" he said.

"My last words to my daughter … on that day [were] 'be safe.'"

'Five, six years … that's a chunk off their youth'

Ms Wong said she believed the courts would not show leniency.

"The judge said that we are taking these offences very seriously because we think they really breached the peace of the society, and imposed stringent bail conditions, so I think the court will be stringent," Ms Wong said.

A few cases have already been decided.

This week, two teenagers were fined $50,000 and told they would receive a custodial sentence for vandalising a train station.

A 16-year-old was sentenced to at least three months in a rehabilitation centre after being found guilty of possessing offensive weapons, including a laser pointer, which protesters have used to disorient police.

The most serious charge looming for some protesters is rioting, which carries a maximum penalty of 10 years.

The protesters have five formal demands of the Government, which include an amnesty for all those arrested and the declassification of the protests as riots.

Hong Kong-Australian lawyer and commentator Kevin Yam is comparing how the courts dealt with similar charges during protests in 2014 and 2016 to today.

"From that perspective, that probably gives us a taste of what's to come."

He said he doubted those convicted of rioting would get the full 10-year sentence.

"But they might get …four, five, six years. If that's a case, that's a chunk off their youth," he said.

"We may or may not agree with their methods, but whatever happens to them is just going to be very sad and devastating."