A son of former media mogul Jimmy Lai has called on all foreign judges to leave Hong Kong’s legal system, adding pressure on them to join an exodus that threatens to erode a key distinction that set the city apart from mainland China.

Sebastian Lai made the remarks at the National Press Club in the Australian capital of Canberra on Monday, part of a campaign by him and his legal team to rally support for his imprisoned father. 

“By staying you’re essentially saying there’s still some semblance of rule of law in this place that imprisons pro-democracy protesters,” Lai said. “And that is not true, that is not true at all.”

Hong Kong’s appointment of overseas judges to its top court has long been seen as a source of confidence for the independence of its judiciary since it returned to Chinese rule. But about half of them have stepped down from a 2019 peak after Beijing imposed a national security law that has been used to silence dissent. 

Lai called on the Australian government to join an international campaign to pressure Beijing to free his father, who is serving prison sentences for a range of offences related to his pro-democracy activism in Hong Kong. Canberra has expressed concerns over Lai’s case, while the US, the UK and the European Union have directly called for his release. 

Lai and six former lawmakers are currently appealing their conviction for joining an unlawful protest in August 2019, with the case being heard in Hong Kong’s Court of Final Appeal. A non-permanent justice from the UK, former Supreme Court President David Neuberger, is among five judges hearing the case.

Lai, 76, is separately facing more severe charges under the national security law that carry a maximum penalty of life in prison. He is accused of conspiring to collude with foreign forces to sanction Chinese and Hong Kong officials.

Asked about the presence of retired UK and Australian judges on the Hong Kong bench, Lai said the growing number of political prisoners in the city showed the foreign jurists were doing nothing to protect citizens from “being oppressed”.

Only seven overseas judges are staying on the city’s top court from 15 in 2019, with four coming from Australia and the rest from the UK.

Hong Kong’s political freedoms have been steadily undermined following Beijing’s introduction of wide-reaching national security legislation in 2020, which was sparked by large, pro-democracy protests in the city over the previous year.

A number of the foreign judges have resigned from the Court of Final Appeal in recent months, with one saying Hong Kong is “slowly becoming a totalitarian state”. The Hong Kong government denied putting any political pressure on courts, saying it has always respected their independent adjudication power.

Speaking alongside Lai’s son on Monday, his lawyer Caoilfhionn Gallagher said her team was “deeply concerned” for the former publisher’s health, adding that no decision had been made yet on whether Lai would take the stand in his own defence in the national security trial resuming late this month.