Critics say that the security law, which took effect in June 2020, puts those freedoms at risk with tough bail provisions and expanded police powers under a legal regime that punishes subversion, terrorism and collusion with foreign forces with up to life imprisonment.
It also gives the city's leader Chief Executive Carrie Lam the power to select which judges will be able to hear national security cases.
The first person convicted under the national security law, Tong Ying-kit, was jailed for nine years on secession and terrorism charges after he rode a motorbike into a group of policeman while flying a protest banner with the words "Liberate Hong Kong, Revolution of our Times."
Hong Kong and Chinese officials say the law was vital to ensure stability after the Asian financial hub was rocked by sometimes-violent protests for much of 2019, and say prosecutions are non political.
Cheung said he was confident that Hong Kong's fundamental human rights, protected by the city's mini-constitution, remained intact.
"The rule of law ensures and promotes fairness, equality and justice, which are the core values in the administration of justice under our system of law," he said.
"Our law reports are full of cases where these fundamental rights are generously interpreted and restrictions narrowly confined by reference to their aim, relevance, necessity and proportionality."
Speaking to the media afterwards, Cheung said he was unable to reveal the number or identities of judges cleared for national security cases, saying that while he could advise and make recommendations to the city's leader, she was the "designating authority" according to the security law.
"I'm afraid the consultation is done confidentially and it's not appropriate for me to disclose any details.
"It's not for us, or for me to answer for her the criteria for designation."
When asked about the ongoing subversion case for 47 high-profile democrats, many of whom have been denied bail for nearly a year and remanded in detention before a full trial, Cheung said while he saw a need for dealing with cases "expeditiously", procedural steps couldn't be rushed.
"These are not steps you can sidestep" he said.