The Hong Kong government announced on Friday that Australian judge Justice James Spigelman has resigned from the Court of Final Appeal.
In response to media inquiries, the Chief Executive's Office said that Spigelman offered his resignation to Carrie Lam as a non-permanent judge of the CFA on September 2, which she accepted.
Australian broadcaster ABC reported that Spigelman told them he resigned for reasons "related to the content of the national security legislation" but did not elaborate further.
Three other Australian judges, justices Robert French, Murray Gleeson and William Gummow, are still serving on the Hong Kong court.
The Hong Kong judiciary has been caught in controversies after the national security law was enacted by Beijing, targeting secession, subversion, terrorism and collusion with foreign forces.
But it attracted criticism globally, with the United States suspending several bilateral agreements with Hong Kong, saying the law had "crushed the freedoms of the people of Hong Kong."
The local bar association and some legal experts say the newly enacted law has undermined the independence of the judiciary, but Hong Kong and Beijing officials deny this.
US allies like Australia have also criticised the new law, further worsening ties between Beijing and Canberra after Prime Minister Scott Morrison's government called for an open investigation into the coronavirus epidemic.