A former opposition politician testifying for prosecutors in Hong Kong’s largest national security trial has expressed sympathy for some of the 47 defendants facing subversion charges over an unofficial primary, saying they had become embroiled in legal trouble due to the “populist” approach adopted by their party leaders.

West Kowloon Court heard on Monday that Au Nok-hin, a defendant-turned prosecution witness, wrote a letter on January 26 to one of the accused to express his views on the high-profile case.

“The key factor, after all, is the individual conduct and speeches [made by the defendants],” Au said in his letter to Tat Cheng Tat-hung, who is among 16 defendants contesting the charge. “I bet in your case, you have been dragged into this by your party.”

Au was cross-examined by the defence on the 20th day of the trial scheduled to last 90 days. Prosecutors have accused the 47 of holding the primary to ensure they won a majority in the Legislative Council so they could paralyse the government by blocking budgets and bills, forcing then leader Carrie Lam Cheng Yuet-ngor to step down.

The 16 denied a joint count of conspiracy to commit subversion when the trial started in early February, while the remaining 31 others have pleaded guilty or indicated they would admit liability.

One of the key documents prosecutors submitted as evidence was an online declaration signed by most of the 47, whereby they allegedly pledged to indiscriminately veto the budgets once they were elected lawmakers.

Tat Cheng arriving at West Kowloon Court in February.

Au’s letter, initially marked as unused material by the prosecution, was taken up by one of the defence lawyers in an attempt to show his client’s lack of intention to flout the Beijing-decreed national security law when he agreed to take part in the unofficial poll in July 2020.

In the document, former lawmaker Au took a critical view of the stance adopted by the Civic Party, to which Tat Cheng belongs, when it began a press conference in March of that year promising its members would block budgets regardless of their merits.

Au said he believed Cheng and Lee Yue-shun, another Civic Party member charged in the case, could have avoided prosecution had the party not been “suddenly scrambling to hold the press [conference] without giving a second thought”.

“If it was not an act to make a populist appeal, what would it be? Was that necessary?” the ex-legislator wrote. “It was not something that you or [Lee] could control, but in the end it put you two in danger.”

The court earlier heard that the Civic Party subsequently signed the online declaration on behalf of its members running in the primary, including Cheng and Lee, who did not endorse the statement in their personal capacity.

Senior Counsel Hectar Pun Hei, defending Cheng, suggested his client and Lee did not have much say over the party’s approach to the primary, adding the organisation’s resolute position might well have been a display of one-upmanship.

But Au said he could not be sure what the pair thought about the pledge.

Au Nok-hin at the Lai Chi Kok Reception Centre in 2021.

He said he did not believe the declaration was binding on the primary’s contestants, adding some who endorsed the statement might eventually vote for the budgets.

The witness said he had believed the primary was lawful until a statement by Beijing’s liaison office in the city on July 14 condemned the event as violating the new law.

He said he made a “political” decision to withdraw from the primary one day later and attempted to undo the damage caused.

He told the court he had once asked journalist-turned official Kenneth Ng King-tsun, then a political assistant with the Constitutional and Mainland Affairs Bureau, whether the organisers’ withdrawal would have saved them and the primary’s candidates from the looming crisis. Au recalled Ng telling him to do as much as he could to remedy the situation.

Au also stressed the primary was brought to a halt after “major figures” called it quits in mid-July after the unofficial poll was held.

“I hope these details can provide better grounds for mitigation to other defendants and legal basis for [the court to show] leniency,” the witness added.

The ex-lawmaker’s evidence continues.