Hong Kong's top judge has called on senior barristers to speak out when the rule of law is threatened and ensure equal access to justice for all.

At Saturday's admission ceremony for three new senior counsel, Chief Justice Andrew Cheung said the newly appointed barristers are responsible for upholding the rule of law and safeguarding the proper administration of justice, in addition to being "highly capable and dependable advocates in court".

"You are expected to speak with courage and conviction where the rule of law is threatened, to maintain the highest standards of professional conduct and integrity, both inside and outside the courtroom, and to uphold the traditions of discipline and courtesy which underpin the profession," Cheung said.

"No less importantly, you must be vigilant in defending the right of every individual to unimpeded access to the courts."

Secretary for Justice Paul Lam told the same ceremony that one of the challenges senior barristers must overcome was in maintaining the city's international image in relation to the rule of law.

"For whatever reasons, many people outside Hong Kong do not have a proper and complete understanding of the present state of the rule of law, and the actual operation of our legal and judicial systems, in Hong Kong... A negative perception, no matter how misplaced, is liable to impair people's trust and confidence in Hong Kong as an international legal and dispute resolution services centre," Lam said.

"Senior counsel, owing to their status as respectable and independent legal professionals as well as skillful advocates, are best positioned to tell the good and true story of Hong Kong in this regard."

Barristers Catrina Lam, Priscilia Lam and Tim Parker are the latest to join the ranks of senior counsel.

Priscilia Lam of Plowman Chambers specialises in criminal law, having representing both the prosecution and the defence regularly. She is the wife of Kevin Zervos, an appeals court judge and a former director of public prosecutions.

Des Voeux Chambers' Catrina Lam primarily practises in commercial and competition law, handling litigation and arbitration; while Tim Parker of Temple Chambers focuses on general civil and commercial practice, including competition and regulatory work.