Liaison and diversion

The National Appropriate Adult Network (NAAN) welcomes the continued development of Liaison and Diversion services (L&D). This short briefing encourages the development of local partnerships with AA schemes and highlights some the key opportunities.

Clarity over the roles

Both liaison and diversion (L&D) and appropriate adults (AA) services featured in the integrated vision set out in the Bradley report (2009). In order to work effectively, L&D practitioners, AAs and custody officers require an accurate, shared understanding of each other’s role and purpose. This includes understanding and respecting each other’s: 

  • expertise;
  • responsibilities;
  • legal powers;
  • aims (both where they are shared and importantly where they diverge).

Although it may seem simple at first, the appropriate adult role is complex. Summary information can be found on this website. The national operating model for L&D defines target groups, aims and outcomes that clearly complement those of appropriate adult schemes (see table below). 


Contacting an AA for any suspect who meets the criteria is a legal duty on police officers[1]. A person cannot refuse to have an AA if they meet the criteria. The AA must be independent of the police and cannot be under their control, direction or contractual arrangements to them.

Although the law prioritises parents in the AA role, there is a requirement on local authorities to provide for children, which is typically delivered via youth offending teams[2]. For adults, PACE prioritises people who are experienced or trained in their care but there is no statutory duty on local authorities to ensure provision. Adult services are often delivered or commissioned via adult social care but there is significant variation in resourcing and some areas have no organised scheme for adults.


AA schemes support the aim of diverting, whenever appropriate, children and adults with mental ill health or other mental vulnerabilities away from the criminal justice system. As an AA is only required for those being treated as a suspect, this allows resources to be focused efficiently. L&D should be aware that disposals that divert a suspect from court, such as cautions applied by police, require the involvement of an AA.


An AA is required for all people aged under 18. However, research evidence strongly indicates that mental vulnerability is significantly under-identified by police officers, especially where there is no organised AA scheme. Police data indicates that on average only 3.1% of adults detentions involve an AA [3]. This drops to 1% in areas with no AA scheme for adults and rises to 5% where there is full provision. Studies by clinical academics indicate a need in the range of 11%-22%. Many front line practitioners would suggest the true rate of need is even higher.

Furthermore, the legal definitions and thresholds in PACE Code C are not always applied and some mental disorders, such as depression and ADHD, seem to be less likely to trigger police to contact and AA.[4]. L&D provides an opportunity to address this, subject to an awareness of the relevant PACE Codes provisions:

  • By law, if an officer has any suspicion that a person may have any mental disorder or be otherwise mentally vulnerable, then unless there is evidence to dispel their suspicion they must as soon as is practicable ask an AA to attend[5].
  • ‘Mentally vulnerable’ applies if, because of their mental state or capacity, a person may not understand the significance (not just the immediate meaning of the content) of what is said, of questions or of their replies.
  • If an officer refers to L&D due to such a suspicion, then the threshold is met and an AA is required. The request for an AA must not depend on any further assessment.
  • It is the custody officer’s legal duty to decide whether an AA is required and this cannot be delegated to an L&D practitioner. Officers may refer to L&D. If they are provided with evidence that dispels their suspicion, the AA can be stood down.

The potential consequences of failing to identify the need for an AA include subjecting innocent people to miscarriages of justice and rendering evidence against guilty people inadmissible in court. If consulted, in addition to advising on reasonable adjustments, L&D practitioners should advise police that an AA is required based on the PACE definition and threshold. NAAN advises that they should not advise police that no AA is required unless:

  • they are confident that they understand the PACE Code definition and threshold; and
  • they have the necessary professional expertise in relation to the suspected condition(s); and
  • they have carried out an appropriate assessment and this has determined that the person has no mental disorder (as defined by the MHA 1983) or other mental vulnerabilty as defined by PACE.

Sadly, early data from the L&D programme suggested that on 20% of adult suspects who enaged with L&D had the support of an AA. A referral from police to L&D will almost always mean an AA should already be involved. However, an AA is not required for a person who is intoxicated, has accommodation issues or has physcial health conditions, if there is is no suspicion of mental vulnerability in addition.

An AA is not just for interviews

There is an unfortunately common misconception that AAs are only required for interviews. In fact the AA has a role throughout a detention episode, from the explanation of rights and entitlements, all the way through to bail or charge and related actions (such as cautions). AAs must be present for all ID procedures (e.g. DNA swabs, fingerprints, and photographs) as well as for strip searches. They have a right to make representations at reviews of detention. They can insist on legal representation for a suspect. A suspect has a right to consult privately with their AA at any time. 

Research indicates that this does not always happen. If L&D are aware of the extent of the legal rements for AA presence, they can help to make sure people receive the support to which they have a right. 

Voluntary interviews

The trend away from arrests towards voluntary interviews presents a shared challenge for police, L&D and AA schemes. Voluntary interviews are still PACE interviews and carry the same risks and, in theory at least the same safeguards. However there is no custody sergeant to provide oversight and L&D and AA schemes are often structured around custody. Many of the people that L&D and AA services exist to support will, for the best of reasons, be increasingly diverted from custody.  While work is underway at a national level to consider these challenges, local partnerships should be considering how L&D and AA schemes can work with police to ensure mental ill health and other vulnerabilities are identified and supported appropriately outside of police custody.

AA referrals to L&D

Where L&D do not conduct universal screening, AA schemes can be a source of referrals. AA support is required for all children in police custody and AAs can spend significant periods of time with a suspect. All adults for whom an AA is required should have been assessed by L&D and practitioners are encouraged to collaborate to ensure that this is the case.

Training collaboration

Liaison and Diversion services may be able to assist the local AA scheme with training of their volunteers or paid staff, for example on mental health or learning disability issues. This can result in better referrals to L&D and improved support and justice outcomes for the individual.

In turn, AA scheme are well placed to support training of L&D practitioners in relation to the relevant provision of the PACE Codes and the support provided by AAs. This can result in improved identification of need and application of the AA safeguard.

Next steps

  1. Identify what AA provision is available in your local area using the NAAN network map
  2. Make contact with the local AA scheme leader and discuss joint working
  3. Work with the AA scheme, and police lead, to review identification of need for an AA
  4. Consider the potential for the local AA leader to sit on any local L&D advisory or steering group and vice-versa.


Table: comparison of L&D and AA provision


Liaison and diversion

Appropriate adults

Target groups

Children and adults with:

  • mental health problems
  • learning disabilities
  • cognitive disorders
  • substance misuse problems;
  • other vulnerabilities

at police stations and courts.

Any suspect who is detained or attends a voluntary interview and:

  • appears to be aged under 18; or
  • an officer suspects may have any mental disorder (as defined by the MHA 1983 s.1) or may be otherwise mentally vulnerable.


Needs addressed include:

  • High prevalence of health and care needs and poor acces to services within child and adult offender populations
  • Poor experience of justice system processes (e.g. long detention times) and outcomes
  • Need for assurance that people have participated effectively
  • Late identification of need increases likelihood of reaching crisis point
  • Lack of information to inform decisions within justice system

When detained or questioned, some people are at high risk of having difficulty understanding:

  • rights & entitlements
  • implications of procedures
  • the significance of questions/replies

They may be prone to:

  • unintentionally providing unreliable, misleading or self-incriminating information
  • unconsciously accepting or acting on suggestions from others
  • becoming confused or unclear about their position

Aims and outcomes

  • Improved access to health and social care services
  • Improved criminal justice outcomes for individuals and the system
  • Diversion of individuals, where appropriate, out of the criminal justice systems into health or other supportive services.

Children and adults with additional needs experience fair justice outcomes because they are:

  • treated fairly with respect for their rights and welfare
  • able to participate effectively in the process


  • Screening
  • Assessment
  • Give advice regarding reasonable adjustments
  • Make referrals to services
  • May not act as an AA (under National Operating Model paragraph 8.3)
  • Proactively safeguard rights, welfare entitlements and effective participation
  • Observe police actions and person’s condition and understanding
  • Support, advise and assist during any procedure, including supporting communication


  • Cross government initiative
  • Funded via NHS England
  • National operating model
  • No statutory requirement but supported by HM Treasury
  • In the process of roll out with 75% population coverage by April 2018


  • Statutory requirement on police to contact an AA (PACE 1984)
  • Statutory requirement on local authorities to provide for children
  • No statutory duty for adults services but often delivered or commissioned via adult social care
  • National standards published by NAAN

[4] Dehaghani, R. (2016). He’s Just Not That Vulnerable: Exploring the Implementation of the Appropriate Adult Safeguard in Police Custody, The Howard Journal Vol 55 No 4. December 2016

[5] Proposed changes to the definition and threshold test currently subject to consultation (as at December 2017)

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