On the night Hong Kong returned to China, leading democrat Martin Lee Chu-ming stood on the balcony of the old Legislative Council building with fellow members of his party and vowed: “We shall return!”

His speech, to the cheering crowds below, followed the disbanding of the legislature by Beijing, in retaliation for the last governor Chris Patten’s electoral reforms. It was replaced by the provisional legislature, a body established by the central government’s Preparatory Committee and chosen by 400 people.

The Democratic Party refused to join the body on principle.

For almost a year there were hardly any opposition voices in the city’s legislature. Now, 23 years after the handover, history is repeating itself. Four pro-democracy lawmakers were disqualified by the government last week after a ruling by Beijing. The opposition camp’s remaining 15 legislators quit in protest. Legco has become an echo chamber.

These developments have serious consequences for the city’s political system and rule of law.

The four disqualified lawmakers were barred by election officials from standing in Legco polls scheduled for last September, mainly because they were deemed to have called for foreign governments to sanction Hong Kong.

But the government deferred the election for a year, citing the Covid-19 pandemic, and sitting legislators were allowed to continue. This left the four democrats– Alvin Yeung Ngok-kiu, Dennis Kwok, Kwok Ka-ki and Kenneth Leung – in place. Chief Executive Carrie Lam Cheng Yuet-ngor suggested in the summer there was no legal basis for disqualifying them. In other words, to do so would be unlawful. That should have been the end of the matter.

But, whether under pressure from pro-establishment lawmakers or Beijing, Lam then asked the National People’s Congress Standing Committee to take action. It did so last week, passing a resolution to allow the Hong Kong authorities to dismiss legislators without approval from the Legislative Council or the courts.

Lawmakers deemed to have advocated independence for Hong Kong, refused to accept China’s sovereignty, invited foreign intervention or endangered national security can now be summarily removed. The government wasted no time in disqualifying the four democrats on these grounds.

They have, therefore, been ejected by the government in accordance with an edict from Beijing. This is a different mechanism from the one provided for in the city’s de facto constitution, the Basic Law, which requires support from two-thirds of lawmakers in the city.

Chief Secretary Matthew Cheung Kin-chung, keen to show his support for the move, used the sort of extreme language which is becoming more common among Hong Kong officials, when attacking the four lawmakers on Sunday. “These people talked black into white, arbitrarily smeared and maliciously attacked the country,” he said.

But the evidence on which they have been disqualified is open to question. The decision to bar them from the September elections was made by returning officers, middle-ranking civil servants. They were accused of acting contrary to the national security law imposed on the city by Beijing in June, even though their actions took place before the law was passed. The election officials appear, in one case, to have taken into account a lawmaker’s mere attendance at a press conference on sanctions. Another was condemned because his party had signalled an intention to block government bills.

The courts have required compelling evidence if candidates are barred from standing in elections and have overturned some decisions. There are questions here for them to consider.

But the four disqualifications have been presented as a fait accompli. There is a lack of due process, as the Bar Association has pointed out. The lawmakers could still attempt to challenge their disqualification in court. Judges are, however, likely to take the view that their hands are tied as a result of Beijing’s intervention.

The significance of this should not be overlooked. The NPC Standing Committee meets every two months. We can only wonder when the chief executive will next be tempted to circumvent the existing legal arrangements by seeking a ruling from Beijing. Our laws are supposed to be clear and certain and to protect us from sudden shifts imposed by the government whenever it considers them expedient. It is another example of rule by law, rather than rule of law.

Core features of the city’s legal system can already be excluded from national security cases. Judicial review, jury trial and open court proceedings can all be dispensed with in certain circumstances under the security law, with exceptional cases to be tried on the mainland.

The legislative council now lacks an opposition. It will be easier for controversial laws to be passed. One of those is likely to allow Hong Kong permanent residents to vote from the mainland, boosting the electoral prospects of the pro-establishment camp in the polls scheduled for next year.

The loss of an opposition in Legco is a tragedy for Hong Kong. Lawmakers have had little opportunity to contribute to policymaking and governance since the handover. But they have a vitally important role in holding the government to account. Their approval is needed for the budget and for government initiatives requiring public spending. Legco can investigate matters of public concern and even recommend to Beijing that the chief executive be dismissed.

Some Legco meetings have descended into chaos in recent times and filibustering has frequently been used by the democrats to delay the passage of bills they oppose. We may long for a return to the days of civil and rational debate. But the sterile meetings we can expect with the opposition absent are not an improvement.

Whether you blame the democrats for quitting or the government for putting them in a position where they felt they had to resign, the vacuum in Legco discredits the city’s constitutional arrangements. Legislators are elected to represent their constituents and a Legco without opposition voices lacks legitimacy.

It can only be hoped that the democrats will return when elections are held next year. But we are in the midst of what appears to be a purge of the government’s opponents. Many have been arrested, candidates have been barred and now lawmakers disqualified. It is already being suggested that all those who resigned will be refused permission to stand next year.

Lee, in his speech on the night of the handover, said “they cannot keep us out of the legislature forever”. He was right. Democrats won around 60 per cent of the vote when elections were next held in 1998. But whether that particular chapter in Hong Kong’s history will be allowed to repeat itself is very much in question.