Government cuts to legal aid for prisoners are under attack at the High Court.
Two charities working with inmates are seeking permission to challenge changes they fear will undermine prisoners' rights and their chances of rehabilitation.
The Howard League for Penal Reform and the Prisoners' Advice Service (PAS) say they have taken legal action as a last resort after Justice Secretary Chris Grayling dismissed their concerns and their arguments that the cuts will cost the taxpayer more.
The application for judicial review in two cases is against restrictions to legal aid imposed by the Government in December 2013.
It raises questions over the legality of the removal of legal aid "without consultation" in parole hearings.
It concerns prisoners on life sentences and IPPs (imprisonment for public protection) who can only progress to open conditions if the Parole Board advises that it would be safe for them to do so.
It also concerns the removal of legal aid for prisoners facing particular difficulties, such as mothers threatened with separation from their babies; children and disabled prisoners who need a support package so they can be released safely, and mentally ill prisoners held in isolation.
"The removal of legal aid to help these children make fresh starts is contrary to the whole aim of the youth justice system which is to prevent reoffending.
"These cuts will not result in savings for the taxpayer. On the contrary, they will result in increased costs as children remain in prison for longer than is necessary for want of a safe home to go to."
Deborah Russo, joint managing solicitor at the Prisoners' Advice Service, said: "PAS provides legal advice to all adult prisoners in England and Wales.
"We run an advice line and receive thousands of letters and telephone calls from prisoners each year. PAS also represents prisoners by taking on legal cases where appropriate.
"The legal aid cuts to prison law have resulted in prisoners' access to justice being severely curtailed.
The Prisons and Probation Ombudsman, the Chief Inspectorate of Prisons and the Parole Board have all expressed grave concern at legal aid being cut for prisoners.
"These cuts are further isolating an already very marginalised sector of our society."