A site foreman fires off a message in the project WhatsApp group, jokey in tone, ending in “lol”, that another reader takes as a threat. Eighteen months later an employment tribunal is reading it word for word. The foreman’s defence, that it was obviously a joke, meant as banter between people who worked together every day, has already been tested in a real case with almost this exact fact pattern. It did not work.
The direct answer to the question in the title is yes, and it is not close. Employment tribunals are, by their own procedural rules, not bound by the ordinary rules of evidence that apply in court, which means there is no special threshold a WhatsApp message has to clear before it can be read and relied on. The interesting legal questions are not whether the messages come in. They are what happens once they do, and construction has its own case law on both.
There is no special rule for WhatsApp, which is itself the finding
Rule 41 of the Employment Tribunal Procedure Rules 2024 states plainly that the tribunal “is not bound by any rule of law relating to the admissibility of evidence in proceedings before the courts”. A WhatsApp message is simply a document, treated the same way as an email or a site diary entry. The real fights are not over whether the message can be read out. They are over relevance, disclosure, and whether destroying a message before litigation makes things worse rather than better.
On that last point there is a genuine, useful case. In Kaur v Sun Mark Ltd a claimant’s entire remedy claim was struck out after she destroyed a notebook and a phone containing a recording relevant to her own case; the tribunal found a fair trial was no longer possible, and the Employment Appeal Tribunal upheld that decision. The lesson generalises directly to a project WhatsApp group. Deleting a group once a dispute looks likely does not make the problem disappear. It tends to make it worse, because a tribunal or court asked to assess conduct it cannot see is entitled to assume the missing material did the claimant no favours.
The banter defence has been tested, and it lost
In Young v Royal Mail Group Ltd, a 2026 Employment Appeal Tribunal decision, a union WhatsApp message sent during industrial action suggested named colleagues should “choose sides”, referenced a car being “blown up”, and ended with “lol”. The employment tribunal found the message “was not excused by being presented in a jokey manner”, that it was “reasonably understood by the recipient as a threat” that “created a sense of menace”, and the sender’s own explanation that it was intended as a joke did not change that finding. The Employment Appeal Tribunal upheld the decision on appeal. A jokey tone at the point of sending does not control how a tribunal reads the message eighteen months later, with the benefit of hindsight and a complainant sitting in the room.
A separate case shows the argument can genuinely divide a tribunal even where it ultimately loses. In Krabou v Tower Hamlets Homes, a three-person panel considering racist and Islamophobic content shared in a work WhatsApp group split two to one on whether the group’s established culture of dark humour, in which the claimant himself had also participated, should soften how his later complaint was read. The majority held it should not. The dissenting member took the opposite view, finding the group’s own tone genuinely relevant to whether the claimant was likely to have taken real offence at the time. The defence is not frivolous, and a tribunal member has been persuaded by a version of it. It has not, on the reported cases, been enough to win.
Construction specifically: a WhatsApp exchange can form the contract itself
This is the finding most site managers underestimate. In Jaevee Homes Ltd v Fincham, a 2025 Technology and Construction Court case, an exchange as short as “Are we saying it’s my job mate so I can start getting organised mate”, answered with “Yes”, was found to have created a binding subcontract between a developer and a demolition contractor, with no formal written agreement in place at all. A message sent to keep things moving on site, in exactly the tone people use when they trust the person on the other end, can be the legal document the whole relationship turns on if a dispute ever reaches court.
The opposite outcome is equally real, and worth knowing as a counterweight. In High Tech Construction Ltd v WLP Trading and Marketing Ltd, a 2026 Technology and Construction Court judgment, the court refused to enforce a roughly two million pound adjudicator’s decision at the summary stage because WhatsApp messages relied on to prove a contract existed were, in the judge’s own words, “equivocal at best”. WhatsApp evidence does not automatically resolve a dispute in favour of whoever produces it. A message that is vague enough to support two readings can cut against the party relying on it just as easily as for them.
Admissible and lawful are two different questions
A High Court case worth knowing in full, because it catches most people off guard, is FKJ v RVT, which involved a firm that had captured around eighty thousand private WhatsApp messages an employee exchanged with her partner and best friend, synced automatically through a work laptop. The employment tribunal admitted this material and the claimant lost her original case. She then brought a separate High Court claim for misuse of private information over the same messages, and won: the court found she retained a reasonable expectation of privacy in the messages regardless of how they had been captured, and described the firm’s use of them as an “impermissible form of self-help”.
The lesson generalises past this specific fact pattern. Winning the argument that a message can be used in one proceeding does not settle whether obtaining or handling it that way was lawful under UK GDPR. The Information Commissioner’s Office is explicit that monitoring workplace messages, including instant messaging and collaboration-tool chat, is likely to capture special category data and requires a data protection impact assessment before it starts, and that employers reviewing personal devices “should ensure” they are not capturing an employee’s private, non-work use of that device in the process. Reading a project WhatsApp group because a dispute has arisen is a different, better-founded action than trawling an employee’s personal phone because it happens to be useful.
The disclosure rule that actually applies to a construction dispute
Most Technology and Construction Court litigation now runs under Practice Direction 57AD rather than the traditional civil disclosure rule, and its definition of a disclosable document is deliberately broad: it “includes e-mail and other electronic communications such as text messages, webmail, social media and voicemail, audio or visual recordings”. The same rule imposes a specific, active duty once a dispute is in view: a party must “take reasonable steps to preserve documents in its control that may be relevant to any issue in the proceedings”, extending to material that would otherwise be deleted under a routine retention policy, with an express obligation to suspend automatic deletion. There is no carve-out anywhere in it for messages that felt informal at the time they were sent.
The scale of this, in two different counts
Two separate analyses, using different methods, agree on the direction even where the exact numbers differ, and both are worth citing precisely rather than blended into one figure. One law firm’s review of tribunal hearings found the number involving disclosure of employee WhatsApp messages rose roughly threefold across a five year window. A separate academic review by University of Salford researchers of over two thousand tribunal cases mentioning WhatsApp since 2019 found the annual count rising more than tenfold over the same period. Whichever figure is closer to the truth, the direction is not in doubt, and it is not moving in the direction that makes an informal site group a lower-risk place to say something you would not want read back to you in a hearing.
What this actually means for how a site group should run
None of this is an argument against using WhatsApp on site. It is the fastest, most reliable way a lot of real coordination actually happens, and the Jaevee Homes case above shows it can carry genuine legal weight when it matters, not just risk. What it means in practice is narrower and more useful: treat anything written in a project group as a document that could be read aloud in a hearing or relied on to prove a contract, because on the reported cases, that is exactly what has already happened to other people’s groups. Do not delete a group once a dispute looks likely, since that has been treated as making a claimant’s own position worse, not better. And do not assume a jokey tone offers cover, because a tribunal has already read the same defence and rejected it in terms that name the exact word, “lol”, that ended the message in question.
Where to check this yourself
Every case and quote above is a real, citable judgment or piece of official guidance, free to read directly.
- “What are the actual rules of evidence in an employment tribunal?” The current procedure rules are free at legislation.gov.uk.
- “What does the ICO say about monitoring workplace messages?” The regulator’s own guidance on monitoring workers is free at ico.org.uk.
- “What does CIOB say about professional conduct and communication?” CIOB maintains member guidance and standards at ciob.org.
- “What UK-wide standards exist for construction contract formation?” RICS publishes its professional standards and guidance library at rics.org.