The SAR's highest court has ruled in favor of the administration over the anti-mask law.

In a 72-page judgment the Court of Final Appeal also said the Chief Executive in Council's use of emergency powers to legislate the anti-mask law complied with the Basic Law.

The administration invoked emergency laws and announced a ban on masks at all protests including authorized ones on October 4 last year.

Chief Justice Geoffrey Ma Tao-li and Justices Joseph Fok, Andrew Cheung Kui-nung, Roberto Ribeiro and Lord Leonard Hoffmann were unanimous in saying the power to make subsidiary legislation under the Emergency Regulations Ordinance - a colonial-era law introduced in 1922 - in an emergency or in circumstances of public danger was wide and flexible and not unconstitutional.

But the power to apply emergency regulations is not unlimited. It is restrained by requirements of the ordinance itself, by the courts through judicial review, by the Legislative Council through negative vetting, and it should meet the proportionality test.

Imposing the mask ban aimed to stop a peaceful gathering turning violent, and a balance was struck between individual rights and the benefits of society, the court said.

"It is clearly proportionate for the Prohibition on Face Covering Regulation to seek to prohibit the wearing of facial coverings - used to hide the identity of lawbreakers and having an emboldening effect leading to degeneration of peaceful protests into violence - whether at an unauthorized assembly, a public meeting or a public procession."

It noted: "The situation on the streets and in other public places in Hong Kong had become dire. Members of the public were fearful of going out to certain places, and significant inconvenience was caused ... by the blockage of roads and closure of public transport."

The court said the use of facial coverings had an "emboldening effect" on protesters and their supporters ... [and] the rule of law was being undermined by the actions of masked lawbreakers."

Twenty-five pro-democracy lawmakers, who have since been unseated or quit the legislature, challenged the constitutionality of the mask ban and emergency laws.

The High Court first ruled in November last year that the anti-mask law was unconstitutional as it went "further than necessary" in the restriction of fundamental rights.

The administration appealed that ruling, and the Court of Appeal in April agreed the banning of facial covering at authorized protests and rallies was unconstitutional. But it affirmed the chief executive's right to invoke emergency powers.

Both parties were unhappy with that ruling and took the case to the Court of Final Appeal.

In response to the latest ruling, former legislator "Long Hair" Leung Kwok-hung said it was harsh to prevent people being masked even at legal assemblies.

But pro-establishment legislators welcomed the judgment. Holden Chow Ho-ding of the Democratic Alliance for the Betterment and Progress of Hong Kong said it reflected justice. And Priscilla Leung Mei-fun of the Business and Professionals Alliance said it could put an end to a debate that has dragged on.

Imposing the mask ban aimed to stop a peaceful gathering turning violent, the court says.

Leung Kwok-hung is disappointed with the court's decision. SING TAO

Let the masks be off, says highest court