A landmark national security trial opened on Monday in Hong Kong for prominent activist and publisher Jimmy Lai, who faces a possible life sentence if convicted under a law imposed by Beijing to crush dissidents.

Lai, 76, was arrested in August 2020 during a crackdown on the city’s pro-democracy movement under the sweeping national security law enacted following huge protests four years ago. He was charged with colluding with foreign forces to endanger national security and conspiring with others to put out seditious publications.

The case — tied to the now-shuttered newspaper Apple Daily — is widely seen as a trial of press freedom and a test for judicial independence in the financial hub.

China promised that the former British colony could retain its western-style civil liberties for 50 years after returning to Chinese rule in 1997. But in recent years, the Hong Kong government has severely limited free speech.