Chung had entered a plea bargain, admitting guilt on the charge of secession and one count of money laundering and pleading not guilty to a sedition charge and another money laundering accusation.
The plea led to a 25% reduction in his sentence, to 40 months for secession and 18 months for money laundering. Only three months of the latter will be served separately, resulting in a total sentence of 43 months.
“He actively organized, planned and implemented activities to separate the country,” District Court Judge Stanley Chan said.
Prosecutor Ivan Cheung has said the defendant acted as an administrator for the Facebook pages of the US branch of Studentlocalism and an organization called the Initiative Independence Party.
Pro-independence T-shirts, flags and books were also seized from his home, the prosecutor said. The money laundering charge was related to donations he received via PayPal.
Like other anti-government organizations, Studentlocalism disbanded before Beijing imposed the security law in June 2020, to punish anything it deems as subversion, secession, terrorism and collusion with foreign forces with up to life in prison.
The vast majority of Hong Kong people do not support independence, but any mention of the idea is anathema to Beijing.
Since the enactment of the security law, Hong Kong has taken a swift authoritarian turn, with most democratic politicians now in jail or in self-exile. Dozens of civil society organizations have folded, and some international rights groups have left the city.
Chinese and Hong Kong authorities deny the security law tramples individual rights and say the legislation was necessary to restore stability after mass street protests in 2019.
The former British colony returned to Chinese rule in 1997 with the promise of a high degree of autonomy. Democracy activists and some Western governments say China broke that promise — an allegation that Beijing vehemently denies.