Context

In recent decades, policymakers have become increasingly aware that our legal definition, which treats all people aged 18 years or older as adults, does not reflect the neurological process of maturation. Policymakers across all parts of the criminal justice system have recognised this although changes in practice are variable at best. There is now a considerable body of evidence on the maturation process and best practice in working with young adults (typically defined as those aged between 18 and 25 years old) in contact with the criminal justice system.

Neuroscience, young adulthood, and maturity 

We know from neuroscience that in all young adults, the brain regions responsible for decision-making and for moderating behaviour are still developing in crucial ways. This affects temperance (self-restraint), responsibility and perspective, which together make up ‘psycho-social maturity’.  During this phase, we may not get the balance right between taking and avoiding risks. Young adults may have difficulty in understanding the pay-off between immediate and consequent actions, perhaps tempted by shorter-term gains that may have detrimental longer-term impacts. Importantly, a number of capacities have not yet integrated fully into young adults’ executive functioning:

• holding back and controlling feelings and behaviour, thinking before acting (including foresight, planning and recognising risk) and taking responsibility for actions; 
• considering different viewpoints and empathy;
• refraining from prioritising peer approval;
• effectively managing stress and emotions, which may be felt more keenly than by more mature adults, particularly when under pressure;
• independence and self-sufficiency;
•  future orientation, i.e. the capacity to envision, engage with and plan for their future, for example setting goals, observing progress and maintaining hope and optimism.

Why maturity matters in criminal justice contexts

While the system currently determines that young people over 18 should be dealt with as adults, it cannot be assumed that becoming 18 is a useful indicator of maturity. Young adults are disproportionately represented in the criminal justice system and make up a significant proportion of prison and probation cases.

Despite constituting 10% of the UK population, in 2022, young adults made up 27% of people in prison and 18% of those on probation in England and Wales. The age-crime curve is a well-known criminological concept that illustrates that young people naturally stop committing crimes as they age: the prevalence of offending peaks during the teenage years and then declines from the early 20s.

Approaches, activities, and interventions

While there are no known evaluations of interventions that aim to increase psychosocial maturity in young adulthood, programmes like HMPPS’s Choices and Changes—a programme of structured exercises for justice practitioners to support young adults who have been identified as having low psycho-social maturity to develop and practice skills related to maturation — and cognitive skills programmes, show effectiveness in building skills like emotion management, problem-solving, consequential thinking and managing impulsivity and reducing re-offending.

These principles were built into HMPPS’ pilots in five prison sites, which sought to build on the evidence as part of its young adult custodial strategy. The dedicated Youth to Adult probation hub, developed in Newham, London by the Mayor‘s Office of Policing and Crime and the Ministry of Justice, has devised a set of ‘young adult first‘ principles to support its working practices, drawing on similar principles for children developed by the Youth Justice Board.

These include using strengths-based, trauma informed and future-focused approaches, ensuring that young adults understand probation requirements and supporting them to meet them, including empowering them to take the lead in their support plan and celebrating their successes.

For readers wanting more detail and resources, please check out the full review.