Explainer | Why Beijing’s angry reaction to Hong Kong High Court’s mask ban decision prompts fears it will overturn ruling

There was a swift response from Beijing when the High Court ruled on Monday that the Hong Kong government’s anti-mask law was unconstitutional. Central government officials criticised the court for failing to support the government in its efforts to end more than five months of increasingly violent social unrest.

For the first time, they suggested that the city’s courts do not have the power to declare a local law invalid by checking it against the Basic Law, the city’s mini-constitution. China’s top legislative affairs body argued that only the national legislature had the right to decide on issues of constitutionality.

Beijing’s reaction left its critics in Hong Kong fearing for the erosion of the city’s independent judiciary. They also feared that Beijing would decide to hand down its own interpretation of the Basic Law and overturn the court ruling. But members of the pro-establishment camp dismissed those concerns, saying Beijing was only reiterating its position. What are the key issues in the controversy over the court ruling?

Why is the court’s decision controversial?

On October 4, after nearly four months of anti-government protests that were becoming increasingly violent, the Hong Kong government introduced a law banning the use of masks in public. It invoked the colonial-era Emergency Regulations Ordinance, a bill which gave the chief executive far-reaching power to enact certain laws in the face of “public danger” and “emergency”. Protesters ignored the ban, but 25 pro-democracy lawmakers turned to the courts, upset that the government had implemented the law without consulting the legislature. On Monday, the High Court ruled that the law, when invoked on the grounds of public danger, was unconstitutional, and that the anti-mask law was excessive.