Opinion | Hong Kong’s Mask Ban Reveals Carrie Lam’s True Face

President Xi Jinping might well have given her the marching order. The Chinese Communist Party (C.C.P.) is haunted by the images of millions of peaceful marchers taking to the streets of Hong Kong to demand the freedom, the human rights protection, the rule of law and the preservation of Hong Kong’s way of life that they have been promised under the Basic Law but have been treacherously denied.

The authorities’ calculation seems to be that if masks are banned, future rallies will be smaller. Some protesters will not be deterred. But others — especially peaceful demonstrators who are civil servants and employees of government-funded NGOs, Chinese businesses or conglomerates that actively trade with China — will be reluctant to assemble or march. Already, the local airline Cathay Pacific has fired employees, including pilots, who had expressed sympathy on social media for the protest movement.

At the same time, the pushback by dedicated protesters this weekend was so predictable that it is impossible not to think that it, too, was a desired effect. The ban was also designed to provoke the more radical factions of the protest movement into escalating violence. Mrs. Lam and the C.C.P. can then invoke any such deterioration, as well as, say, acts of arson — or even, some fear, crimes by agent provocateurs planted by the police — to call the movement a riot and its participants vandals.

One of their hopes is that more Hong Kongers may then distance themselves from the movement because of the increased social costs. Another is that the movement will lose some of the moral authority it seems to command with liberal democracies around the world.

A more sinister explanation is that further violence on the streets could become an excuse to impose a curfew, formally or de facto, and pass other extreme emergency regulations. Members of the major pro-government party are also said to worry about their prospects in the district council elections scheduled for late November: Chaos would be a convenient pretext to postpone or cancel those.

Legislators from the democratic camp have started a legal battle challenging Mrs. Lam’s ordinance and are asking that it be reviewed judicially. The High Court refused this weekend to order an interim injunction to stop the ban from taking immediate effect but has said that the case could be heard in full before the end of October.

We already knew that “One Country, Two Systems” was dying; now we know that the rule of law is dying too.

Alan Leong Kah-kit, a former chairman of the Hong Kong Bar Association and former member of the Hong Kong Legislative Council, is chairman of the Civic Party.

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