Within the context of youth justice being an area of much political and public debate, and with increasing globalisation and policy transfer youth justice is important to analyse and assess in terms of systems functions. Irelands’ youth justice legislation, took influence from the innovative youth justice system of New Zealand. This resulted in an altering model of youth justice within Ireland and New Zealand away from a strict welfare model. The focus increased justice-based elements of holding children and young people responsible for their offending behaviour, while maintaining a welfare ethos, including attention to victims needs. Due to this approach being innovative, and attracting significant international attention, this research aims to assess if the models of youth justice have changed in Ireland and New Zealand since the relevant legislation in 1989 in New Zealand and 2001 in Ireland, up to policy in 2023. The examination, guided by the underlying models of justice relevant to these youth justice systems, will highlight the innovative approaches’ progress, and journeys in New Zealand and Ireland.