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ACAS Guidance - Conducting Workplace Investigations

Posted on January 18th 2016 by

ACAS have provided further guidance for employers on how to conduct workplace investigations.

The guidance (which provides a useful “at a glance” flowchart) is designed to offer additional support to employers leading an investigation process for disciplinary, grievance and general conduct matters.

The paper outlines 6 key steps that should be looked at when dealing with an investigation. These are as follows:-

1.   Organisational Preparation

According to ACAS, it is fundamental that sufficient and significant preparation is completed prior to the commencement of an investigation.

The type of preparation which may be appropriate is extensive but in summary includes:-

  • Considering whether an informal discussion should take place at the outset, to see if the issue can be resolved early on;
  • Considering if a preliminary investigation will help;
  • Consider how long the investigation might take;
  • Deciding who would be most appropriate and effective in dealing with the matter and appointing that person accordingly; and
  • Keeping the matter confidential so as to avoid any influence on the investigator, to name but a few.

In essence, the aim of this first step is for employers to get to grips with the nature of both the issue/complaint raised, alongside the key steps that will need to be taken during the investigation procedure. This allows them to ensure that the next steps taken are the most appropriate and effective to ensure all parties involved are treated fairly.

2.  An Investigator’s Preparation

The guidance suggests that an investigator should make an investigation plan, which will encourage a structured approach to the investigation procedure.

Such a plan will allow the investigator to remain focused on the key facts, and the type of evidence that required collection. Through the preparation of a thorough plan, an investigator will also be aware of the time frame they have available, and are more likely to stick to this (rather than letting the process drag on).

An investigator should be realistic, and expect to modify their plan if and when appropriate. ACAS provides a useful checklist for investigator’s to use at

During the preparation step, an investigator should be sure to consider the relevant policies and procedures in place to the matter. They should identify where possible evidence that may come from, possible parties who they may wish to interview (asking them to provide 

witness statements where appropriate), and decide in what order they wish to obtain evidence.

Following this, an investigator should establish when and where the investigation meeting will be held. ACAS advises that meetings should be at the employee’s normal place of work and during working hours. However, in a practical sense, if a matter is highly confidential, investigator’s may wish to do the meeting outside of working hours.

Finally, the investigator should contact all relevant parties and their managers. If an employee is under investigation they should be notified in writing of the allegations against them, and should be informed of who to contact if they have any queries during the procedure. The employee in question should also be given written notice of their investigation meeting. The details to be included are outlined in the ACAS guidance at page 18 –

3.  Handling an Investigation Meeting

Whilst investigation meetings are not obligatory, many scenarios will require them, rather than simply a collection of written and physical evidence.

An investigation meeting is designed to provide an investigator with the opportunity to interview someone who is involved in, or has details on, the matter under investigation.

An interviewee is permitted to be accompanied by a workplace colleague, or trade union representative, and in some circumstances, employer’s may even choose to allow the individual to bring in a close personal friend or family member.

If an investigation meeting is necessary, an investigating officer should consider how they will record the meeting. They may choose to take notes themselves, or alternatively have a designated note-taker. The latter option permits the investigating officer to focus solely on what is being said by the interviewee, and consider what additional questions may need to be asked.

The ACAS guidance suggests that the notes of the meeting should contain the following:-

  • The date and place of the interview;
  • Names of all people present;
  • An accurate record of the interview;
  • Any refusal to answer a question; and
  • The start and finish times, and details of any adjournment.

An employer should be aware that investigation meetings are often emotional and difficult, especially for an individual who has raised the complaint, or is under investigation. It is therefore fundamental that a structured process, with significant forward planning, is undertaken by an investigator.

4.   Gathering Evidence

It is fundamental that when gathering evidence, an investigator reminds themselves that their role is to establish the facts of the matter. They should therefore consider both evidence in support of the allegation, and evidence against it.

Investigators may take witness statements from employees (which will essentially be a signed copy of the notes from an investigation meeting), and these may be typed up or hand written.  It is advised that an employee who has been interviewed is given a copy of the meeting note to check that it is accurate. This should be done sooner rather than later, to avoid time passing and their memories of the meeting becoming hazy.

In addition, investigators will collect documentation that may be useful to establish facts of the matter, and may in certain circumstances use physical evidence too for example, CCTV and computer records. Some of this physical evidence may be difficult and expensive to collect, and therefore an investigator should consider whether it truly is reasonable to proceed.

Finally, investigators may be required to collect evidence through searching an employee’s personal belongings. It is fundamental that there is a clear, legitimate reason for doing so, and that employee consent is obtained. Where consent is not granted, such conduct may be deemed as unreasonable behaviour which could jeopardise key evidence. However, an investigator should be sensitive throughout such a process, as an employee may have a genuine reason for rejecting such a search. An investigator must ensure that a refusal to be personally searched does not imply guilt, but instead attempts to resolve this issue.

5.   Writing an Investigation Report

Having established the facts of the case as far as reasonably possible, an investigator will next need to produce an investigation report, confirming their findings.

Whilst such reports are not mandatory, they often give those reading them a better understanding of the procedure that has taken place, and how the subsequent outcome was reached.

The report should cover various points, including:-

  • A basic introduction providing details of the person authorising the investigation; the person conducting the investigation; and an overview of the circumstances that led to the investigation;
  • Details of the process that was carried out to investigate the matter. This should include what evidence was collected; which employees were spoken to and where no evidence was collected or an employee could not be spoken to, the reason for this. When considering evidence, the ACAS guidance suggests that an investigator should arrange their evidence into the following categories:-
  1. Uncontested facts;
  2. Contested facts; and
  3. Unsubstantiated claims;
  • The findings of the investigation. This is self-explanatory but should in essence summarise what has been established following the investigation process, and what has not been established; and
  • A conclusion providing recommendations moving forward.

The report should also attach any documents to which reference is made.

6.   After an Investigation is Completed

Once an investigator finishes their reports they may be required to discuss the report in person, input into a policy or procedure review, or attend the disciplinary hearing.


In essence, the paper is designed to offer further assistance to those conducting an investigation and to help remove the risk of any possible claim from an employee further down the line. The guidance is clear and concise, making it easier for employers to digest and put it into practice as and when necessary.

At Kitsons, we have a team of employment specialists who can assist you with a workplace investigation. Whether it be a disciplinary matter, or an employee’s grievance, our team have knowledge to cover both. Please contact us on



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Leave a comment

Shaun Backett

Shaun Backett says: February 8th, 2018 at 11:47 am

During an investigation, is it allowed that an interviewer actually does his own notes and doesn't have a designated note taker?
Carolyn Giles

Carolyn Giles says: February 9th, 2018 at 3:28 am

Hi Shaun & thank you for the comment. Yes. The investigator needs to take comprehensive notes, and as long as they feel able to interview a witness / employee whilst taking good quality notes, there is no need for a note taker. (Caolyn Giles, Kitsons LLP)
Naveed Aslam

Naveed Aslam says: March 14th, 2018 at 11:48 am

My query is I am having an investigator interview. My line manager initially during the start said to me it was informal, whilst telling me this she's is keeping notes of mine and her conversation. I remind her that as your recorded what I am saying, I would need to have union representation. My manager told me I did not need union representation as it was informal , during further interviews I have found out that the matter has now gone uoto an Area Manager level, baring in mind I was told this was informal and then out of the blue I have been told that I will need to have an investigator interview. I was clearly anxious, stressed and angry after being told this and ended up going off sick with work related stress.... I would like to know where I stand with this, can I add I have noticed that this manager treats other people differently and similiar incidents have not been deal with in the same manner.
Carolyn Giles

Carolyn Giles says: March 14th, 2018 at 3:10 am

Hi Naveed,

Thank you for your comments.

As you are asking very specific questions relating to your case, we would recommend that you read the ACAS guidance that is available for free, or if you wish to take legal advice from our team, we can be contacted on 01752 603040.

ACAS also have a free helpline you may wish to access: 0300 123 1100.

I hope this helps and many thanks for engaging with us.

(Carolyn Giles, Kitsons LLP)

Ian says: March 17th, 2018 at 9:44 am

Hi my wife has been dismissed from work after an investigation for racial discrimination my question in we now know the investigation interviewed 25+ staff members but only the 3 peaple who made allegations against her statements where produced as evidence .this seems wrong to me as now know a lot of the other statements all said they never witnessed any racial discrimination from her. Just looking for advice as to whether this is acceptable? Thanks
Carolyn Giles

Carolyn Giles says: March 20th, 2018 at 10:58 am

Hi Ian,

I’m afraid this is not an appropriate forum to discuss individual cases. With this in mind, please do contact our employment team for specific employment advice on 01803 202020.

From there we will be able to help in confidentiality.

(Carolyn Giles, Kitsons LLP)