There is "convincing evidence" showing ousted pro-democracy lawmaker Lau Siu-lai does not uphold the Basic Law, a government counsel told a High Court hearing her election petition yesterday.

In a by-election in November 2018, Lau was barred from running in the Kowloon West constituency. She then filed an election petition to challenge the decision made by election officer Franco Kwok Wai-fan and to unseat incumbent Rebecca Chan Hoi-yan.

The ruling was adjourned to a later date.

Lau, 44, from Democracy Groundwork, was disqualified from the Legislative Council in 2017 in the oath-taking controversy. She wanted to take part in the by-election in 2018 to win back the seat she vacated, but was barred from standing in the by-election, with Kwok saying he believed Lau had always considered Hong Kong independence an option and that she refused to acknowledge the central government's authority over the SAR.

However, senior counsel Paul Shieh Wing-tai, representing Lau , said: "The election ban was unreasonable because she was denied a chance to explain her political views."

He added that Lau was denied due process, as all candidates have a right to defend themselves.

Shieh also said Lau issued a statement in support of the Basic Law during the by-election campaign, and that the election officer had chosen not to trust it and instead stuck to comments she had made in the past.

He cited the case of Demosisto's Agnes Chow Ting, who won her election petition when a judge ruled that one should be given the chance to explain their stance.

Shieh also raised the example of former lawmaker Edward Yiu Chung-yim, who was also unseated during the oath-taking saga but was allowed to participate in the 2018 by-election and lost to a pro-establishment opponent.

Government counsel Johnny Mok Shiu-luen said Lau's situation was different from that of Chow and Yiu, as it was clear Lau did not uphold the Basic Law.

Lau's oath-taking incident had a lingering effect, since she had not shown any repentance or change in her political stance until shortly before the by-election, Mok said.

Mok also said that Lau's case should not be handled as a normal election petition, as her disqualification was related to an interpretation of the Basic Law.

Lau election ban appeal heard