Investigation - Specialist Advice/Opinion

Specialist Advice/Opinion


This guidance is designed to promote consistency across HSE and enable specialists to function more effectively, either as investigators with specialist knowledge or as independent expert witnesses.


The guidance applies to all specialists in HSE when providing specialist advice, or giving a specialist opinion, in support of investigations.

The guidance applies equally to England, Wales and Scotland. Whilst the Police & Criminal Evidence Act 1984 (PACE) and the Criminal Procedures & Investigations Act 1996 (CPIA), do not apply in Scotland, the equivalent principles and procedures should be followed.

It does not apply to the provision of specialist advice/opinion in the context of safety case assessment.


In this guidance, a specialist is acting:

either as an investigator with specialist knowledge, who:

supports an investigating officer, or acts as the investigating officer themselves

or as an independent expert witness, who:

provides independent assistance to the court in relation to matters within their area of expertise

The investigating officer is the person in overall charge of the investigation


HSE has a paramount responsibility to safeguard health and safety.

The specialist's primary role is as an investigator.

The role of investigator and expert witness are usually mutually exclusive and a specialist inspector is unlikely to be appointed as an independent expert if he/she becomes directly involved in the investigation.

The decision as to whether an 'independent expert' is required and who it should be rests with the person responsible for assessing the evidence on behalf of HSE, so a specialist must not assume the role of an 'independent expert' at the outset.

It is HSE's policy that unless otherwise advised, specialists should not hold back from becoming involved in incident investigations because of concerns relating to their position as an 'expert' being compromised.


Specialists acting as investigators should use their specialist knowledge to safeguard health and safety whilst assisting the investigation.

Specialists acting as independent experts are appointed on behalf of the court to provide opinion evidence on matters that fall within their particular area of expertise.


As an investigator with specialist knowledge, the specialist will:

  • support and advise the investigating officer in examining the cause of the incident
  • in some situations, act as the investigating officer themselves
  • record and retain information consistent with the statutory requirements on investigators
  • identify and pursue all reasonable lines of inquiry
  • establish the means by which the incident could have been prevented
  • recommend how future incidents could be avoided
  • provide technical evidence in court on matters relevant to the investigation

As an independent expert, the specialist will:

  • provide independent assistance to the court in relation to matters within their area of expertise
  • present evidence uninfluenced by the arguments of either side

As an investigating officer:

  • provide clear instructions as to the nature of the resource required (including objectives, priority and timescales)
  • formalise the request on COIN


Line managers should ensure, via normal management activity, that those involved in operating this procedure carry out their responsibilities in line with the standards and timescales described. They should make sufficient documented checks to satisfy themselves, and to prove to any subsequent audits, that the procedure is being operated correctly.

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Updated 2020-12-14