The National ARMS Evaluation

The Risk Management of Registered Sex Offenders

There are approximately 60,294 registered sex offenders (RSOs) in England and Wales, all of whom are managed in the community by the Police and Her Majesty’s Prison and Probation Service (HMPPS). A vital part of the ongoing management of registered sex offenders (RSOs) is accurate risk assessment, which helps to differentiate offenders by risk level, allowing for the allocation of appropriate treatments and resources.

An evidence-based national evaluation

In collaboration with the National Police Chief Council (NPCC) and Her Majesty's Prison and Probation Service, we conducted a two-year national evaluation of the risk assessment tool used by all 45 Police forces in England and Wales as well as by Her Majesty’s Prison and Probation Service.

Introduced in England and Wales in 2014, the Active Risk Management System (ARMS for short) provides a national standard for the risk assessment and management planning of sexual offenders. ARMS is a structured assessment process to assess dynamic risk factors known to be associated with sexual re-offending, and protective factors known to be associated with reduced offending.


Utilising a mixed methods approach, the ultimate aim of the research was to identify how police and probation could most effectively use the risk assessment tool to manage and monitor registered sexual offenders in the community. The results will be used as the baseline data on which all future decisions, and further developments, of ARMS, is based.




A National Evaluation of the Active Risk Management System