Under its handover deal with the British, Beijing promised to guarantee until at least 2047 certain liberties and autonomy not seen on the authoritarian mainland.
But fears China’s ruling Communist Party was steadily eroding those freedoms helped to build a powerful pro-democracy movement, which led to massive and often violent protests for seven months last year.
China has made no secret of its desire to use the law to crush the democracy movement, and to intimidate those who want to resist.
“The Hong Kong government will vigorously implement this law,” Chief Executive Carrie Lam, the city’s Beijing-appointed leader, told reporters on Tuesday.
“And I forewarn those radicals not to attempt to violate this law, or cross the red line, because the consequences of breaching this law are very serious.”