Hong Kong national security law: arresting opposition figures was the easy part for authorities – making charges stick will require powerful evidence, legal experts say

• Police allege the former lawmakers and activists broke the national security law by vowing to paralyse the government during last year’s primary election
• But prosecuting them will require proof the campaigning involved at least the threat of force and a central piece of evidence is expected to be an essay penned by organiser Benny Tai, lawyers say