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Sociology: Improved registered sex offender management in England and Wales

Prof Samantha Lundrigan, Dr Natalie Mann

Research conducted by ARU researchers from 2015 to 2019 investigated the effectiveness of current registered sex offender (RSO) community management.

This research resulted in key changes to policy and practice in all 43 police forces and all seven divisions of the National Probation Service (NPS) in England and Wales.

Explore ARU researchers' original work via our open access repository, ARRO

Research summary

There are currently 64,325 RSOs in England and Wales. These individuals are managed by specialist police teams and the NPS (Ministry of Justice, 2021).

Two research projects examined the effectiveness of risk management practices for RSOs in the community, including the first national evaluation of the Active Risk Management System (ARMS). ARMS was introduced in England and Wales in 2014 as a national standard for the risk assessment and management planning of sexual offenders (College of Policing, 2014).

Dr Mann's research involved extensive fieldwork with Essex Police public protection teams and the impact of ARMS on police and probation staff workload.

The research identified that reduced resources, arising from austerity measures, had negatively impacted police sex-offender management and hindered collaboration between police and probation officers, this led to a detrimental effect on the police’s ability to protect the public.

Between 2017 and 2019, Prof Lundrigan and Dr Mann conducted the first national evaluation of ARMS, the objective of which was to provide criminal justice decision-makers with the evidence base to inform the future direction and development of the ARMS tool.

This was achieved through a programme of mixed-methods research (interviews, focus groups, observations, and inter-rater reliability exercises) that engaged all 43 police forces (100%) and all seven NPS regions (100%) in England and Wales.

ARMS was embedded across all 43 police forces in England and Wales but adoption of ARMS into the National Probation Service (NPS) was less successful.

Differences in the approach taken to risk management by police and the NPS had led to discrepancies in how the ARMS tool was both used and perceived. Rather than encouraging collaboration, the joint use of ARMS served to highlight the differences between the agencies and their role in managing offenders. 

The evidence suggested a divide between police practitioners, for whom the tool was well embedded into practice and a standardised approach to RSO management, and NPS practitioners, for whom ARMS was a duplication of the NPS Offender Assessment System (OASys).  

There were several limitations identified in the delivery of ARMS training for police and probation officers, single agency training had contributed to variable practices and a lack of joint agency working.

There was also a need among police officers for regular and updated training, to supplement their initial training and communicate any changes in practice. 

A number of risk factors were identified as difficult to rate for practitioners, as well as a number of groups of individuals who were challenging to assess, for example, RSOs with mental health issues, learning difficulties, or who were transgender. Practitioners felt the case studies used in training did not represent the variety of offender types they are required to manage.  

Seventeen recommendations were put forward from the national ARMS evaluation arising from the research. Ten of these recommendations were subsequently implemented by police and/or the NPS, resulting in changes to national policy and practice for ARMS practitioners, particularly in relation to the development of the new ARMS-informed OASys tool, and changes to national ARMS training practices. 

A man with his hands behind his back being handcuffed by a Police officer

Summary of the impact

  • Led the NPS to develop develop a new, more efficient risk management tool
  • Informed improvements to national training for ARMS practitioners
  • Strengthened sharing of best practice and collaboration between agencies


A key recommendation of the national evaluation was that: consideration should be given as to whether ARMS remains the most effective tool for NPS use. This recommendation was 'an important factor in the decision to change the use of ARMS in the NPS' (HMPPS Head of Assessment and Management of the Sex Offending Policy team).

Prof Lundrigan and Dr Green's research found that current policy requiring probation officers to complete both an ARMS and a probation specific (OASys) risk assessment was significantly increasing the workload of probation officers through the duplication of risk assessment information.

As a result of these findings, the NPS developed a new risk management tool, the ARMS-informed OASys (AiO). The new digitalised AiO tool became fully operational in July 2020 and is currently being used by probation officers in all seven divisions of the NPS.

Substantial resource savings across England and Wales have been made due to this development, meaning NPS officers no longer need to complete an additional ARMS assessment for RSOs managed in the community, increasing efficiency.

Read more about read more about the development of a new arms-informed oasys (aio) assessment for the national probation service (nps) .

Prof Lundrigan and Dr Mann's research also identified several gaps in ARMS training delivery as well as a lack of joint agency working, arising from an historical lack of collaboration between the police and probation services.

They recommended that this be addressed through new ARMS training practices. As a result, widespread changes have been made to national ARMS training for police and probation officers across all 43 police forces and 7 NPS regions in England and Wales, including:

  • Initial ARMS training for all new police and probation officers delivered as a single training package
  • Annual ARMS refresher training for all ARMS force trainers
  • ARMS training materials developed to reflect the findings of the research and the gaps in training identified by the participants.
  • NPS training in relation to the new AiO tool, including a half-day of training with the local police offender-management team on the role of each agency in ARMS practice.
Read more about read more about improvements to national training for arms practitioners .

Prof Lundrigan and Dr Mann's research identified a lack of best practice sharing and knowledge exchange among offender managers across England and Wales. In response to this, they Mann developed and delivered five interim findings from the national ARMS evaluation, to share best practice on sex-offender management and create resilient offender-management networks.

The researchers co-hosted two national conferences with the National Police Chiefs’ Council (NPCC) in 2017 and 2019, attended by 400 delegates from public protection units, government, charities, and academia across the United Kingdom.

Feedback from respondents showed that the conference would impact positively on their practice. Many respondents commented that the conferences were highly informative and relevant, and highlighted the benefits of sharing knowledge with other practitioners.

Further workshops were delivered by Prof Lundrigan and Dr Mann for public protection officers, attended practitioners from 21 different police forces and criminal justice agencies, including the Home Office and National Crime Agency.

These events have resulted in the sharing of best practice and collaboration between agencies.

In November 2020, as a result of the research conducted in the field of sex offender management, Prof Lundrigan was awarded £860,000 by The Dawes Trust to deliver a programme of applied research in the investigation and prevention of child sexual abuse and exploitation (CSAE).

In collaboration with the National Police Chiefs’ Council, Home Office, Ministry of Justice, charities/third sector and technology partners, this funding will enable the development and delivery of a research and innovation strategy which addresses significant gaps in the understanding of CSAE and the operational needs to investigate and prevent it.

Read more about read more about strengthened sex offender management networks and facilitation of best practice sharing.

United Nations Sustainable Development Goals

We have mapped our REF 2021 impact case studies against the United Nations' Sustainable Development Goals (SDGs).

The 17 SDGs, adopted by all UN Member States in 2015, are an urgent call for action. They recognise that ending poverty and other deprivations must go hand-in-hand with strategies that improve health and education, reduce inequality, and spur economic growth – all while tackling climate change and working to preserve our oceans and forests.

This case study is mapped to SDG 5: Achieve gender equality and empower all women and girls, target 5.2.

See also

Read the full REF 2021 impact case study for UoA 21: Improved registered sex offender management in England and Wales

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