Shiu, a former lawmaker, made the appeal on an RTHK programme after the watchdog said it would initiate an investigation into the operational arrangements for the statutory visits.
It said on Thursday that it would also look into the support provided by the relevant departments before, during and after JP visits, and would make recommendations for improvements where necessary.
Members of the public and concern groups can send any views on the issue to the Ombudsman by August 15.
The last time the government reviewed the system was 22 years ago.
Shiu, who spent time behind bars himself in connection with the 2014 Occupy protests, said he welcomes the watchdog’s decision. But he added that he hopes it will not just be all words and no action, and that the Ombudsman will collect views from prisoners, their families and concern groups.
He said under the current system, prison staff are present when prisoners make complaints to the JPs, which he said is unnecessary and makes it hard for inmates to speak freely.
Prison staff also ask inmates before JP visits if they intend to make complaints, and then try to persuade them not to, Shiu said.
He said staff are also able to prevent prisoners from meeting the JPs, by moving the inmates around the prison to keep them away from the visitors.
JPs regularly visit 38 institutions, including prisons, detention centres, psychiatric hospitals, remand homes, places of refuge, probation homes and reformatory schools.
The Correctional Services Department, for its part, condemned people for making “baseless accusations” about its staff.
In a statement, it said it has a well-established mechanism in place to ensure all inmates can make complaints to JPs.
The department added that there are also other channels available for them to voice their dissatisfaction, including taking the matter to legislators, the Ombudsman, or the Equal Opportunities Commission.
Last updated: 2021-07-16 HKT 21:19