For liaison and diversion


Learning resources

Identifying vulnerable people

The appropriate adult role

Working with appropriate adults

Next steps


NAAN strongly encourages the development of local relationships between liaison and diversion (L&D) and appropriate adults (AA) services, as part of the integrated vision set out in the Bradley report (2009).

We work with NHS England colleagues to support this at the national level. But effective local relationships are critical.

We hope the information on this page is of assistance to L&D professionals. 

Learning resources

Slide deck (PDF)

This PACE vulnerability and appropriate adults slide deck supported a 2 hour training session for liaison and diversion schemes. It was arranged by NHS England and delivered by NAAN in April 2022.

If you'd like to commission us to deliver this training for your team, just drop us a line using this form

2022 PACE vulnerability icon

Identifying vulnerable people

How does PACE define a vulnerable person?

The provisions about vulnerability in the Police and Criminal Evidence (PACE) Act 1984 Code of Practice C were significantly amended in August 2018.  

This 1.5 minute video sets out the definition of a vulnerable person under the revised PACE Code C . It was developed for social media, to support the publication of the NAAN research report, There to Help 3 (2020)

What proportion of people are vulnerable in PACE terms?

This is a complex question and there is no definitive answer. However, studies by clinical academics indicate that 39% of adult suspects have a mental condition or disorder.

Do all vulnerable people get an AA?

Under the Police and Criminal Evidence Act 1984 Code of Practice C, an AA is required for all people for whom the police have reasons to suspect may be vulnerable. 

However, research has shown that: 

  • Without appropriate tools, mental vulnerability is significantly under-identified by police officers
  • Vulnerable suspects are under-identified according to police data.
  • The identification of vulnerable suspects has been shown to be lower in areas with no organised AA scheme for adults
  • 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.
  • Early data from the L&D programme suggested that the AA safeguard was applied by police to only 20% of adult suspects who enaged with L&D.


What are the consequences of under-identification?

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.

What does this mean for L&D?

L&D don't decide whether the AA safeguard applies to an individual - that is the responsibility of the police.

However, L&D do use their skills to provide relevant information to support justice decision-makers (e.g. the police). Both the Liaison and Diversion Standard Service Specification (2019) and PACE Code C make it clear that L&D play an important role in ensuring that the need for an AA is identified. 

If consulted, L&D practitioners should provide police with relevant information based on the PACE definition and threshold. This requires that L&D professionals:

  • are confident that they understand the PACE Code C definition and threshold; and
  • have the necessary professional comptencies in relation to the suspected condition(s).

The appropriate adult role

Being an appropriate adult (video)

This 9-minute video about being an appropriate adult was developed to help untrained appropriate adults (typically family members) understand their role. It is also helpful for professionals who are looking for a brief overview of the role. We'd be grateful for your professional feedback on the video. 

About appropriate adults (video)

You can also watch this 6 minute video that answers some of our frequently asked questions about appropriate adults

Here are a few important facts about the appropriate adult procedural safeguard:

  • An AA is required for all people aged under 18, and anyone of any age about whom the police have reason to suspect may be a vulnerable person (as defined by PACE Code C).
  • Contacting an AA for any suspect who meets the criteria is a legal duty on police officers (PACE Code C).
  • A person cannot refuse to have an AA if they meet the criteria; it is not a 'right'; and as there is no decision for them to make, the issue of capacity is not relevant. 
  • The law prioritises parents in the AA role for children, and "people who are experienced or trained in their care" for vulnerable people
  • There is a legal requirement on local authorities to provide AAs for children (Crime and Disorder Act s.38(4), typically delivered via youth offending teams
  • 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.
  • The AA must be independent of the police; they cannot be under the control or direction of the police force, or have contractual arrangements.
  • 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). Research indicates that this does not always happen.
    The specific rules are complicated, and sometimes police can do some procedures without an AA, but AAs are definitely not just for interviews. 
  • A detained person has a right to speak privately to their AA at any time
  • AAs have a wide range of rights, for example they can insist that a solicitor attends, and make representations at reviews of detention.  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.  

Working with appropriate adults 

Why work together?

On the L&D side, the Liaison and Diversion Standard Service Specification (2019) states that L&D shall:

  • "provide advice to decision makers within youth and criminal justice agencies on the range and appropriate use of reasonable adjustments for those
    individuals identified with vulnerabilities, including advising on the appointment of an appropriate adult"
  • "have reinforced links to other relevant services which should include appropriate adult services".

For AA schemes, the National Standards for appropriate adult provision state that:

  • scheme leadership should be actively engaged with L&D
  • L&D should be involved in supporting AA training delivery if possible
  • AA training should enable AAs to explain how their role is distinct from others, including L&D
  • AA schemes should have a clear managing potential conflicts of interest, covering applicants who are employed in a role in custody, including L&D
  • AA schemes should be included in local inter-agency protocols, setting out respective roles
  • AAs make representations for assessments by L&D where appropriate.

How do L&D and AA services fit together?

In order to work together effectively, its important to understand both the distinct differences L&D and and AA services and the significant shared interests.

This means that 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 and aims (both where they are shared and importantly where they diverge).

The table below provides a comparison. 


Liaison and diversion

Appropriate adults

Target groups

Children and adults at police stations and courts with:

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

Any suspect who is detained in police custody or attends a voluntary interview under the Police and Criminal Evidence Act 1984 and:

  • appears to be aged under 18; or
  • an officer has reason to suspect the person may be a vulnerable person


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 
  • 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
  • Standard Service Specification (2019)
  • 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 and approved by national bodies
  • Provide information to police that constitutes a reason to suspect a person is vulnerable (and therefore police need to secure an AA)
  • Can provide referrals to L&D, based on information given to them by the person they are supportingr L&D
  • All adults for whom an AA is required should have been assessed by L&D if available

What about voluntary attendance at interviews?

  • Many of the people that L&D and AA services exist to support will, for the best of reasons, be increasingly diverted from custody.
  • 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 the same AA safeguard.
  • However there is no custody sergeant to provide oversight and L&D and AA schemes are often structured around 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.

Can we collaborate locally on training?

  • NAAN encourages local AA and L&D providers to collaborate on training
  • The local AA scheme could provide L&D with awareness training on the role of the AA
  • L&D services may be able to assist the local AA scheme with training of their AAs (e.g. on mental health or learning disability issues).
  • This can result in and improved support for the individual and better justice outcomes. 

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 ensure processes for the identification of need for an AA are effective and comply with PACE
  4. Consider the potential for the local AA leader to sit on any local L&D advisory or steering group and vice-versa
  5. Encourage your local police force to use the AA video for family AAs (we've developed a video implementation page for them).