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The Sequential Intercept Model – trauma-informed diversion
HMI Probation Academic Insight on the Sequential Intercept Model - a trauma-informed diversionary framework.

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The Sequential Intercept Model

The latest (26 January 2024) Academic Insight from HMI Probation  highlights how the ‘Sequential Impact Model’ (SIM) can be used as a trauma-informed  framework which identifies key stages and opportunities for diverting children and adults with complex needs from the                 criminal justice system or from penetrating deeper into the system. The report is written by by Dr Suzanne Mooney, Dr Stephen Coulter, Professor Lisa Bunting and Dr Lorna Montgomery who describe how the SIM was originally developed in the USA as a cross-systems framework to consider the interface between the criminal justice and mental health systems.

The authors highlight how the SIM can be used more widely as a trauma-informed framework which identifies key stages and opportunities for diverting children and adults with complex needs from the criminal justice system or from penetrating deeper into the system.


The authors start by explaining how the SIM has been utilised as a strategic planning tool to assess available resources, determine service gaps, identify opportunities, and develop priorities for action to improve system and service-led responses focused toward adults with mental health and substance use problems who are involved with the CJS. The SIM is premised on the recognition that the CJS is often ineffective at meeting the multi-faceted needs of people with complex needs, and that justice involvement itself can exacerbate existing difficulties, inadvertently increasing the likelihood of reoffending.

The SIM has been extensively piloted and refined over the last six years. The original model delineated five intercepts corresponding to key criminal justice processing decision points: law enforcement; initial detention/initial court hearings; jails/courts; re-entry; community corrections. An additional intercept (‘community services’) was formally added to the model in recognition of the dual roles played by the police in protecting public safety and serving as emergency responders to people in crisis. Police officers and emergency services therefore form an essential part of the ‘crisis care continuum’.
It is argued that these six decision points represent junctures where people could be prevented from ‘entering or penetrating deeper into the criminal justice system’ and diverted to alternative services that are more appropriate to their needs. Each intercept therefore functions as a filter, with interventions ideally ‘front-loaded’ to ‘intercept’ people early in the pathway and thus curtail criminal justice involvement to its lowest level.

These six “intercepts” are summarised in the infographic reproduced below.

Key messages

The report presents six key messages which apply across all six intercept stages. These include best practice principles developed by SIM advocates as well as two additional overarching themes identified in the literature reviewed. Readers will see that these messages appear to translate well to the UK context.

Cross-systems collaboration and service co-ordination
Collaborative and co-ordinated efforts across systems and services are identified as essential to avoid justice-involved persons with complex needs falling through the inevitable gaps that emerge when multiple service providers do not take shared responsibility for the person’s welfare and commit to working together to this end. One of the unfortunate consequences of our keys of austerity has been the weakening of partnership work as organisations were forced to concentrate on their key activities.

Information-sharing and performance measurement
Unsurprisingly, effective information-sharing within and between agencies and services is deemed essential to achieve consistent and effective cross-system collaboration and co-ordination to better meet the multi-faceted basic health and social care needs of justice-involved persons (such as safe accommodation and access to primary healthcare) as well as targeted treatment and support for specific mental health conditions or substance use issues.

Routine identification of complex needs
At each intercept, there is a need for routine identification of people with complex needs, including mental health and substance use issues as well as other issues identified as common in justice-involved persons (such as adverse childhood experiences, trauma, domestic violence, care experience, homelessness). In the UK, this appears to work best in our Liaison & Diversion schemes although the work of RECONNECT for prison leavers is beginning to look promising.

Links to healthcare and social support services including housing
This principle reminds service providers of the need to ensure justice-involved persons across all intercepts have appropriate access to basic health, social care and financial supports including social security, safe housing and social supports in the community. As all readers know, access to safe housing in particular has been a long-standing challenge in the UK.

Strengthening supportive relationships with family and friends
Strengthening informal support networks is key to assist successful engagement of vulnerable children and adults with an appropriate range of heath and social care service provision prior to or upstream in their involvement with the CJS. Despite the Farmer Review, family work is the exception rather than the norm within our CJS. 

Including peers with lived experience
The inclusion of peers with lived experience of mental health service provision and specifically the CJS is a consistent theme in the design and delivery of effective practice innovations and the UK has a burgeoning lived experience movement.


Clearly, we are a long way short of having a Sequential Intercept Model in the UK. I for one would love to see it highlighted as a manifesto pledge by the main political parties ahead of this year’s election.


Thanks to the blowup for kind permission to use the header image in this post which was previously published on Unsplash.

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