When Louis Lo was arrested at the height of Hong Kong’s 2019 pro-democracy protests and accused of masterminding the city’s largest bomb plot in decades, authorities chose not to prosecute him for terrorism.

At that time, the city had never charged anyone with trying to carry out a terrorist act under a law passed years earlier for just that purpose. Instead, the independence activist, who the trial judge said sought to create "terror among citizens,” was charged with keeping explosives. He pleaded guilty in April and was sentenced to 12 years in prison.

Yet Hong Kong has shown a greater willingness to level terrorism charges since China imposed powerful national security legislation on the city last year. Authorities began using its sweeping provisions to round up members of the opposition in the former British colony, arresting 29 people on terrorism-related allegations in the past 18 months — the first just hours after the security law took effect on June 30, 2020.