On the eve of the local council elections, Hong Kong grapples with constitutional turmoil, verily over the prerogative of China over its protectorate. Beijing has stiffened its position a day after Hong Kong’s High Court ruled that a ban on wearing face masks during public demonstrations, that have rocked the island nation and financial hub for more than five months, was unconstitutional.

The shadow-boxing has taken off in good measure; China’s National People’s Congress has said that Hong Kong courts have no power to rule on the constitutionality of legislation under the city’s Basic Law, which includes a proposed ban on face masks. Beijing has insisted it held the sole authority to rule on constitutional matters in the region, an assertion that spells disaster for Hong Kong’s rule of law, indeed the bedrock of its success as an international financial hub.

The embattled Hong Kong chief executive, Carrie Lam, proposed a ban on face masks as the pro-democracy demonstrations escalated. Protesters had been using masks to hide their identities in public. The proposal was widely criticised by supporters of the anti-government movement who saw it as posing a risk to demonstrators. The High Court ruled on Monday that colonial-era emergency laws, which were revived to justify the mask ban, were “incompatible with the Basic Law”, the mini-Constitution under which Hong Kong was returned to China in 1997.

In the event, China has reinforced its interventionist stance. Its latest statement comes amid chaos in Hong Kong which has been convulsed by pro-democracy protests since last June. Over the past 24 hours, police have fought running battles with protesters trapped inside a university campus. Specifically, Polytechnic University was surrounded by a security cordon on Tuesday morning. Overnight several groups of protesters were countered with teargas as they tried to escape.

Police have said protesters inside have no option but to surrender. China’s move has dealt a serious blow to Hong Kong’s rule of law and the “one country, two systems” policy, which has granted Hong Kong extensive autonomy since the handover from British rule and underpinned its success as an international finance centre. It has also rendered Hong Kong’s courts ineffective since it can arbitrarily override their decisions. Hence the fear of academics at the Hong Kong Baptist University that “Hong Kong’s judicial system is now at risk of submitting to China’s Marxist-Leninist socialist legal system, which envisages that the law and the courts must serve the Communist party as instruments of power struggle”.

The ideological compulsion is now pretty obvious and the face-mask has effected a critical churning. China’s strong-arm strategy has overshadowed Ms Lam’s governance and alienated the citizenry further still. Has Beijing run out of patience with the one country, two systems paradigm? It has made it clear that the law must serve politics.