Article 23 of the city’s mini-constitution, the Basic Law, stipulates that Hong Kong shall enact its own laws to prohibit seven types of offences: treason, secession, sedition, subversion against the central government, theft of state secrets, foreign bodies’ conducting political activities in the city, and local bodies establishing ties with foreign bodies.

… Pro-democracy advocates fear it could have a negative effect on civil liberties.

Yeah, I’d say that would indeed have a negative effect on civil liberties.