People involved in the criminal justice system are one of the population target cohorts of Core20PLUS5, a national National Health Service (NHS) England approach to support reduction of healthcare inequalities. For the health and justice system to be socially equitable, fair and just, the leadership across the health landscape has a central role to play to ensure this vulnerable group has an equitable opportunity for improved healthy life expectancy, regardless of their multiple disadvantages. On the 75th year of the inception of the NHS, this article is a call to action to bring about sustainable change through data reporting, digital innovation, accelerating preventative programmes and system leadership in order to achieve equitable access, excellent experience and optimal outcomes. It acknowledges the detrimental impact of crime and the importance of improving a range of health and social outcomes for this group.

Background A small proportion of every nation's young people become sufficiently antisocial to come into contact with the criminal justice system. Many also have disorders of mental health or emotional well-being. Although countries vary in designating age of criminal responsibility, all must provide services for offenders, perhaps as young as 10, both to help them and safeguard their peers and the wider public. Aim The aim of this article is to map the range of research required to support the development of satisfactory services for young mentally disordered offenders and identify knowledge gaps from a practitioner's perspective. Methods Using a public health prevention framework, we identified the main streams of research pertinent to young, mentally disordered offenders and sought examples of each to consider the extent to which they have been used to inform service development in England. Findings As in most countries, service development seems first driven by unusual, newsworthy cases. Overall, however, current English provision follows sound primary, secondary, and tertiary prevention principles with parallel tiers of service, including public health initiatives. Primary prevention and more specific treatments are likely to be informed by research findings, but service structure tends to emerge from a wider review base, including criminal justice, social and educational practitioner reviews, and also politics. Thus, services and populations of service users may change in advance of research evidence. Substantial reduction in numbers of young offenders in prison in England, for example, is clearly good in principle, but the intensity of need in the residual group is posing new challenges to which there are, yet, few answers. Conclusions Although the last 15 years of coordinated service development in England has been broadly theoretically based, it has not been systematically assessed to establish what works best for whom. New problems emerging, such as new drugs of misuse, and new opportunities, such as technology for supporting and monitoring, require model studies. More research focusing on correlates of success is essential.