He is also seeking a temporary ban on Au taking office.

Former Bar Association chairman Ronny Tong Ka-wah, now a member of the Executive Council, said the arguments against Au would be hard to prove.

“Such actions could easily give people a feeling that a person is not willing to uphold the Basic Law, and I completely understand that,” he said on a radio programme on Wednesday.

“But from a purely legal standpoint, the burning of the Basic Law could suggest two intentions: one is indignation – the person could be frustrated at certain articles and wants to vent the resentment.

“Another is that the person fundamentally does not accept … the Basic Law and is using the burning as a form of expression.”

Tong said neither intention could be determined simply by looking at an action. Context, environmental factors and what the person said must also be taken into account.

“Intent is not easy to prove. It must be deduced from facts,” he added.

Hong Kong’s opposition pan-democrats apologise to supporters after Legco by-election defeat

The annexe lists all the national laws that can be applied locally in Hong Kong “by way of promulgation” or adapted to suit the city’s system.

Au said whether a person was willing to uphold the Basic Law and pledge allegiance to Hong Kong should not be judged based on a past action. “People’s views can change,” he said.

Unlike burning a national flag, burning a copy of the Basic Law is not a criminal offence, though Tong urged those seeking to take part in legislative politics not to do anything to “provoke any unnecessary political or legal clashes”.

The barrister and former lawmaker said that judges vetting judicial review applications would also consider whether there were other legal means to handle a conflict and balance the costs incurred by society. In the case of disputed elections, the normal appeal mechanism is an election petition.

“In general, in terms of judicial reviews, the likelihood of a temporary ban being imposed in such cases is quite low,” Tong said.

Au, an independent, had taken her place to represent the opposition camp in the race for the Hong Kong Island constituency seat. He bagged 137,181 votes to beat the New People’s Party’s Judy Chan Ka-pui, who got 127,634.

Chow said she had been discussing with her lawyer whether to challenge the returning officer’s decision to invalidate her nomination on grounds that her party, Demosisto, advocated self-determination for Hong Kong.

“The possibility is quite high,” she said. “[The petition is] not just for myself but for those who want to participate in elections in the future.”

Chow said the decision was difficult to make as if the challenge was successful, the result of the Hong Kong Island by-election could be nullified.