The group of pro-democracy politicians and activists are accused of subversion for organising an unofficial primary.

The defendants are accused of “subversion” for organising an unofficial primary to choose their candidates for the 2020 Legislative Council election that the government later postponed blaming the coronavirus pandemic.

There was a heavy police presence, including officers with dogs, outside the West Kowloon Magistrates’ Courts building.

Some people began lining up overnight for a seat in the public gallery, with the queue snaking around the building by the morning.

“There’s certainly huge sympathy for the people who are standing trial,” said Al Jazeera’s Richard Kimber, reporting from Hong Kong. “There’s certainly a lot of frustration that it’s taken this long to get to this stage and that those who’ve been detained have not been able to speak out since they were arrested.”

Those charged include prominent activists Leung Kwok-hung, known as “Long Hair”, and Gordon Ng Ching-hang, who faces potential life imprisonment as one of five people accused of being a “major organiser” of the primary.

Those who have pleaded guilty include internationally-known activists like Joshua Wong, and Claudia Mo, a former journalist turned legislator.

Together, the 47 accused account for much of what remains of Hong Kong’s pro-democracy leadership after mass protests calling for political reform in 2019 came to an inconclusive end with the COVID-19 pandemic, and the national security law pushed many into exile.

The trial is expected to continue for 90 days.

Sentencing of all the defendants will take place after it has concluded.

Under the security law, which took effect on June 30, 2020, the defendants face up to three years in prison for conspiracy to commit subversive activities, between three and 10 years imprisonment for “active participation” in the conspiracy, and between 10 years and life imprisonment if they are deemed “principal offenders”.