The ruling comes amid what critics say is an erosion in Hong Kong’s rule of law and individual rights amid a sweeping national security crackdown by Beijing that has jailed scores of opposition democrats and shut down liberal media outlets.

The case has implications for internet freedoms and the operations of firms including internet platform operators (IPOs) and technology firms such as Google.

Court of Appeal judges Jeremy Poon, Carlye Chu and Anthea Pang wrote that the composer of the protest song had intended it to be used as a weapon.

“In the hands of those with the intention to incite secession and sedition, the song can be deployed to arouse anti-establishment sentiments,” the judges wrote.

The judges added that “an injunction is necessary to persuade the IPOs to remove the problematic videos in connection with the song” from their platforms.

“Although the IPOs have not taken part in these proceedings, they have indicated that they are ready to accede to the Government’s request if there is a court order.”

Chinese Foreign Ministry spokesman Lin Jian said during a regular press briefing that “preventing anyone from using or disseminating the relevant song… is a legitimate and necessary measure by (Hong Kong) to fulfil its responsibility of safeguarding national security”.

Freewheeling Hong Kong returned from British to Chinese rule in 1997, with the guarantee its freedoms would be preserved under a “one country, two systems” formula.

Hong Kong does not have its own anthem. “Glory to Hong Kong” was written in 2019 amid mass pro-democracy protests that year and was considered an unofficial national anthem, rather than China’s “March of the Volunteers”.

The court ruling targets those who broadcast or distribute the song with the intention of inciting others to commit secession, or those who suggest Hong Kong is an independent state, or who insult the national anthem.

Exceptions would only be granted to lawful academic and journalistic activities, the judges added.

The Hong Kong government sought an appeal after High Court Judge Anthony Chan refused to ban the protest anthem last July, saying that it could undermine freedom of expression and cause potential “chilling effects”.

The government applied for the injunction last June, after it was mistakenly played at several international events as the official anthem, including a Rugby Sevens game and an ice hockey competition.

Google gave no immediate response to a request for comment. It had earlier said it wouldn’t change its search results to display China’s national anthem rather than the protest song when users search for Hong Kong’s national anthem.

DGX Music, the music group behind the song, did not immediately respond to a Reuters request to comment.

The song was banned in Hong Kong schools after China imposed a national security law in 2020. In March, authorities enacted another set of national security laws that some foreign governments say further undermine rights and free speech.

Beijing rejects the accusation and says the security laws have brought stability. (Reporting by Jessie Pang; Editing by James Pomfret, Michael Perry and Nick Macfie)