Hong Kong's lawmakers on Wednesday approved the appointment of William Young, 73, to join five other overseas non-permanent justices from the UK and Australia.

Hong Kong is a common law jurisdiction separate from mainland China and invites overseas judges to hear cases at its Court of Final Appeal.

Their presence has been seen as a bellwether for the rule of law since the former British colony was handed back to China in 1997.

Beijing passed a national security law on Hong Kong in 2020, following huge and often violent pro-democracy protests in the Chinese city the year before.

Since then, several overseas judges have quit the Court of Final Appeal without finishing their terms, while others have not renewed their appointments.

The lineup of overseas judges has gone from 15 at its peak down to five, not including Young.

The newly appointed justice, who retired from his role as a New Zealand Supreme Court judge in April 2022, is expected to start in Hong Kong this month.

Hong Kong leader John Lee accepted a recommendation to appoint Young in May and praised him as "a judge of eminent standing and reputation".

Cases at the top court in Hong Kong are typically heard by a panel of four local judges and a fifth ad hoc member, who may be a foreign judge.

In January, Hong Kong's chief justice said recruiting suitable overseas judges "may be less straightforward than it once was", given geopolitical headwinds.

The government has defended the security law as necessary to restore order after the 2019 protests and said the city remains a well-respected legal hub.