Cafodd y Grŵp Rhanddeiliaid Cyfiawnder ei sefydlu gan y cyn-Weinidog Gwasanaethau Cyhoeddus yn 2015 i ystyried diwygiadau Llywodraeth y DU i'r system gyfiawnder a'r corff cynyddol o gyfraith ddatganoledig Cymru. Daeth y Grŵp ag academyddion ac ymarferwyr ynghyd sydd â gwybodaeth a phrofiad helaeth o'r sectorau cyfiawnder a chyfreithiol yng Nghymru. Cyfarfu ar bum achlysur rhwng Gorffennaf 2015 a Chwefror 2016 a chyflwynodd ei ganfyddiadau i'r Gweinidog Gwasanaethau Cyhoeddus mewn adroddiad o dan y teitl Law and Justice in Wales: Some Issues for the Next Assembly.
The Justice Stakeholder Group was set up by the former Minister for Public Services in 2015 to consider the UK Government’s reforms to the justice system and the growing body of devolved Welsh law. The Group brought together academics and practitioners with extensive knowledge and experience of the justice and legal sectors in Wales.  It met on five occasions between July 2015 and February 2016 and presented its findings to the Minister for Public Services in a report Law and Justice in Wales: Some Issues for the Next Assembly.