WhatsApp messages in a disciplinary hearing

The standard: a fair process under the Acas Code

There is no special rule for WhatsApp in a disciplinary. A message is evidence like a witness statement, an email or a CCTV clip, and the standard that governs how it is gathered and used is the one that governs the whole process: the Acas Code of Practice on disciplinary and grievance procedures. The current Code was issued under section 199 of the Trade Union and Labour Relations (Consolidation) Act 1992 and came into effect on 11 March 2015. In its own words, "A failure to follow the Code does not, in itself, make a person or organisation liable to proceedings. However, employment tribunals will take the Code into account when considering relevant cases", and they can adjust an award "by up to 25 per cent for unreasonable failure to comply with any provision of the Code".

Behind the Code sits the test of unfair dismissal in section 98(4) of the Employment Rights Act 1996: whether "in the circumstances (including the size and administrative resources of the employer's undertaking) the employer acted reasonably or unreasonably in treating it as a sufficient reason for dismissing the employee", determined "in accordance with equity and the substantial merits of the case". How the employer came by a message, and what it did with it, is part of that reasonableness.

The Code's own summary of fairness is six elements, and every one of them touches message evidence. Employers and employees "should raise and deal with issues promptly"; they "should act consistently"; employers "should carry out any necessary investigations, to establish the facts of the case"; they "should inform employees of the basis of the problem and give them an opportunity to put their case in response before any decisions are made"; they "should allow employees to be accompanied at any formal disciplinary or grievance meeting"; and they "should allow an employee to appeal against any formal decision made".

A new Code is on the way. Acas consulted on a draft Code of Practice on disciplinary and grievance procedures from 30 July to 23 September 2026, with more emphasis on informal resolution and on fact-finding that is "objective, reasonable, proportionate". Until a revised Code is approved and laid before Parliament, the 2015 Code is the one tribunals apply, and this guide quotes it.

How messages reach the employer

The route by which a message arrived matters more than its content when fairness is tested, because it decides whether using it intrudes on anyone's privacy and how far it can be trusted. In practice there are six routes, and they are not equal.

1. A recipient reports it. A colleague, a parent, a volunteer or a resident's relative receives a message and brings it forward, often with a complaint. This is the commonest route and the least problematic: the message came to the employer legitimately, from someone entitled to share what was sent to them.
2. Another member of a group shares it. Someone in a staff group chat screenshots a post and sends it to a manager. Also usually legitimate, but the sender's motive and the completeness of what they chose to capture both need asking about.
3. It is on the organisation's own systems. A message sent on a work device or through a work account the employer runs. Using it depends on what staff were told about access to those systems in advance, which is where the ICO's employment guidance on monitoring workers applies.
4. The employee provides it. The employee under investigation produces their own messages, in their defence or because they were asked. They are entitled to decline to hand over a personal phone.
5. It was public. A post visible to anyone. Privacy is weaker, although context and proportion still matter.
6. Someone went looking. A manager reads an unlocked phone, logs in to a linked device, or asks a colleague to forward a private conversation they were not part of. This is the route that turns a disciplinary into a second problem, for the reasons in the next section.

Acas's guidance on carrying out an investigation sets the habit that makes any route defensible: "The person investigating should keep a written record of how and why they got any evidence." For a message that record is short and it is worth writing on the day: who provided it, when, in what form (screenshot, forwarded message, exported chat), from which device, and what they said about how they came to have it.

Privacy, Article 8 and messages sent in private

Article 8 of the European Convention on Human Rights, given effect in UK law by the Human Rights Act 1998, says: "Everyone has the right to respect for his private and family life, his home and his correspondence." Public bodies must act compatibly with it, and employment tribunals take it into account when they judge whether a private employer acted fairly. Data protection law runs alongside: a message about a named person is personal data, and using it in a disciplinary is processing that needs a lawful basis and must be proportionate under the UK GDPR and the Data Protection Act 2018.

A message does not lose its privacy just because an employer has seen it. In FKJ v RVT [2023] EWHC 3 (KB), a High Court decision refusing an employer's applications to strike out or end a misuse of private information claim, the court said that "no explanation or authority has been offered for the proposition that private information downloaded to a work laptop (a very common scenario) thereby loses its private character", and that for the bulk of the messages "there was no relevance to the Employment Tribunal proceedings and no justification for their retention or use". It was a procedural ruling rather than a final decision, but the point is the one employers most often miss. The question the courts ask is whether the person had a reasonable expectation of privacy in the information, and a message sent to friends in a private group chat can carry one even when it later reaches a manager. In FKJ the messages had already been used in employment tribunal litigation; the privacy claim came afterwards, as a separate action.

The ICO's guidance on monitoring workers points the same way: workers' expectations of privacy "are likely to be significantly greater at home than in the workplace", and it is "not always easy to distinguish between workplace and private information" when "some workers may also use personal devices for work".

There are no formal rules of admissibility in an internal hearing, and an employment tribunal decides for itself what evidence to consider, so improperly obtained messages are not automatically excluded. What changes is the employer’s position: evidence obtained unlawfully can undermine the fairness of the process and expose the employer to a separate claim, which is a poor trade for a screenshot it could have obtained properly. None of that makes private messages unusable. Where the conduct in a message affects the employment relationship, such as harassment of a colleague, a discriminatory remark about a service user, a breach of confidentiality about a pupil, or a threat, an employer that received it legitimately can normally rely on it, proportionately. The practical rules follow from that:

• Use the messages that are relevant to the allegation, not the whole chat. Extracts with enough context to be fair, and the rest left out.
• Do not go looking. Reading a personal phone, a linked device or an account without consent is the step that turns a fair investigation into an intrusion the employee can challenge.
• Limit who sees the messages, and keep them with the case file rather than in managers' inboxes and phones.
• Tell the employee what you have and how you came by it, so that, in the ICO's words, workers "can see and, if necessary, explain or challenge" the material, "within, or alongside, disciplinary or grievance procedures".
• Where the conduct is a safeguarding matter in a school, a care service or a charity working with children or adults at risk, the safeguarding route comes first: the allegation is handled under the organisation's safeguarding procedures, including, for an allegation about someone who works with children, referral to the local authority designated officer (LADO), and the disciplinary follows rather than leads.

Messages in the investigation and the hearing

The Code's steps apply to message evidence exactly as they apply to anything else, and each one has a specific consequence.

1. Investigate before deciding. The Code asks employers to investigate "without unreasonable delay to establish the facts of the case", and "where practicable, different people should carry out the investigation and disciplinary hearing". The investigator's job with a message is to establish what it says, who sent it, when, to whom, and what surrounded it. An investigatory meeting "should not by itself result in any disciplinary action".
2. Put the messages in the letter. If there is a case to answer, the employee is told in writing with "sufficient information about the alleged misconduct or poor performance and its possible consequences to enable the employee to prepare", and "it would normally be appropriate to provide copies of any written evidence". The messages relied on are written evidence. Send them, with dates, times and senders where known, not a summary of what they are said to show.
3. Go through them at the hearing. At the meeting "the employer should explain the complaint against the employee and go through the evidence that has been gathered", and the employee "should be allowed to set out their case", with "a reasonable opportunity to ask questions, present evidence and call relevant witnesses" and to "raise points about any information provided by witnesses". The member of staff who took the screenshot is such a witness.
4. Allow the companion. The statutory right to be accompanied by a fellow worker or a trade union representative applies where the meeting could result in a formal warning or other disciplinary action; the companion may put and sum up the worker's case and confer with them, but not answer questions for them.
5. Decide in writing, on the evidence you hold. After the meeting the employer should "decide whether or not disciplinary or any other action is justified and inform the employee accordingly in writing". Where misconduct is found, the outcome letter should say which messages were relied on and why their meaning was accepted.
6. Hear any appeal afresh. The appeal "should be dealt with impartially and, wherever possible, by a manager who has not previously been involved in the case", and an appeal is often where new messages, from the employee's phone, first appear.

Two points of consistency catch employers out. A group chat has other members, and if others posted in the same vein and only one is disciplined, the Code's expectation that employers "act consistently" will be tested. And the messages will name third parties, so disclose them to the employee with other people's personal data removed where it is not needed to understand the allegation, as the subject access guide explains for a redaction pass. If the employee makes a subject access request during the process, as many do, it runs on its own one-month clock alongside the disciplinary.

Authenticity, context, and the employee's own copies

Acas asks investigators to consider whether "there are any doubts over the credibility and reliability of the evidence", and to weigh evidence that "supports and does not support the allegations". For messages that means four questions, asked before the hearing, not in it.

• Is it complete? A screenshot shows what one screen displayed. Ask for the messages before and after, and for the whole exchange where it is short. A joke, a quotation or a reply to something now deleted reads very differently in context.
• Who sent it? A name in a chat is how the recipient saved the number. Establish the number, and whether anyone else had access to the phone.
• When? Screenshots often show a time but not a date. Timing can decide whether conduct was in work time, before or after an instruction, or during a period covered by a previous warning.
• Has it been changed? A screenshot can be edited with ordinary tools. Where authenticity is disputed, the original device, or an export made from it by the person who holds it, is better evidence than an image. The evidence guide sets out what each kind of copy can prove.

The employee's own phone is the other half of the evidence, and it is usually the fuller half. The employee holds the whole thread, including messages sent to them that explain or provoke what they said, and messages the reporting colleague did not capture. The employer cannot compel them to produce it, but it should invite them to, record that it did, and take seriously what comes back. An employee who produces a fuller record at the hearing or on appeal is not being difficult; they are doing what the Code allows when it gives them the chance to "present evidence".

The asymmetry cuts both ways. The employer often holds a fragment chosen by someone else. The employee holds the thread, and may also hold the messages in which managers discussed the case, which is the subject of the next section. A decision to dismiss for gross misconduct built on one screenshot, without having asked for the rest, is the kind of decision section 98(4) reasonableness is designed to test.

The other messages in the case: the managers' own

Every disciplinary that starts with a WhatsApp message produces more WhatsApp messages, and they are rarely the employee's. The deputy forwards the screenshot to the manager on a Sunday with "have you seen this?". The manager replies "this is the last straw". The investigator and the hearing manager discuss the evidence in a direct message before the hearing; the chair of trustees is kept informed in a group chat. Those exchanges are about the employee, so they are the employee's personal data and within a subject access request, and if the case reaches a tribunal they are documents the employer must disclose if it has the power to obtain them, including the ones that do not help.

They are also the evidence of whether the process was fair. The Code wants different people to investigate and decide, and a decision taken with an open mind. "This is the last straw" on a Sunday, from the person who later chairs the hearing, is exactly the message an employee's representative asks for, and it sits on a personal phone the organisation cannot search, under whatever retention its owner has chosen. The employee, who was in none of those chats, may still end up with them through a subject access request, while the organisation has to ask its own managers what they said.

The answer is not to stop managers talking about a case; that is how a case gets managed. It is to have those conversations somewhere the organisation holds. ComplyChat gives work conversations a channel the organisation owns, recorded on the server as messages are sent, with everyone added told that the channel is on the record and able to object or leave, and on paid plans the lasting record files into the organisation's own Microsoft 365 once its tenant is connected. The employer's side of a disciplinary can then be produced from its own record, with its dates, rather than assembled from managers' phones. It does not reach WhatsApp chats, it cannot supply the screenshot that started the case, and it is not an HR case management system. ComplyChat Free is personal messaging with one private group, direct messages and three calendar months of recent history, with no Microsoft 365 archive, so it is not a record for a case that may run for years.

A question for the next leadership or trustees' meeting: in the last disciplinary, if the employee had asked for every message the organisation's managers exchanged about their case, could the organisation have produced them, and would it have been comfortable doing so?

Official guidance and your next step

The primary sources are the Acas Code of Practice on disciplinary and grievance procedures (2015), Acas's step-by-step guidance on investigations and on the disciplinary hearing, section 98 of the Employment Rights Act 1996, and the ICO's employment guidance on monitoring workers. Quotations are from those pages as published on 25 September 2026. Watch for the revised Acas Code following the 2026 consultation, and check the date on any ICO page, because the Data (Use and Access) Act 2025 has amended data protection law and the ICO is still updating its guidance to match.

This guide is a summary for employers in Great Britain, not legal advice. Whether a particular message can fairly be relied on depends on how it was obtained and what it shows; take advice from a solicitor or an HR adviser before acting on messages from a personal device, and before any dismissal.

Clear policies help on both sides: a staff messaging policy that says what conduct in work group chats is covered by the disciplinary rules, and a procedure that says how message evidence is handled. Then do one thing: add a line to your disciplinary procedure saying how message evidence is handled, that the investigator records who provided each message, when and how; that the employee receives copies of the messages relied on; and that nobody accesses a personal phone or account without consent.