THE families of 20 prisoners serving indefinite jail terms since their youth joined human rights activists in a demonstration at Government House yesterday. The 50 protesters, including representatives from Amnesty International and Union Church Hong Kong, called for an immediate review of the cases and urged the Government to set dates before the handover for the prisoners' release. Governor Chris Patten this week admitted denying Mok Kwok-yuen, 37, a fair chance of being released by referring his case to the Board of Review on long-term prison sentences instead of considering it himself. Mok was detained for an undefined period at 'Her Majesty's pleasure' after being found guilty of murder as a teenager 19 years ago. Legislator Leung Yiu-chung said parents had lost confidence in the Board of Review. 'The prisoners have been treated unfairly for a long time,' he said.