Offensive WhatsApp messages between staff — can I discipline for things said outside work?

The answer Just Ask, HR gives

Concise Charlie — Direct, no fluff — the bottom line first.

Bottom line: yes, out-of-hours conduct can be disciplinable — when it has a genuine connection to work. A staff group mocking a colleague clears that bar.

The test is not where or when the messages were sent. It's the impact on the workplace: the victims are colleagues, the audience is colleagues, and the working relationship is now damaged. Harassment under the Equality Act 2010 doesn't stop at the office door — and you can be vicariously liable for harassment "in the course of employment", which case law has stretched to work-adjacent social settings and group chats.

Act in this order:

• Preserve the evidence — get the screenshots formally, note who provided them and when.
• Support the targeted colleague first. Take their account, ask what outcome they want, consider interim separation of duties — not suspension of the victim.
• Investigate before labelling. Authenticity, context, who wrote what, who merely stayed silent in the group. Participation and authorship are different levels of culpability.
• Then run your normal disciplinary process. Depending on severity, outcomes range from a warning to gross misconduct dismissal for the authors.

Check your policies: if your disciplinary policy or bullying and harassment policy doesn't explicitly cover conduct on personal devices and social media affecting colleagues, fix that now — it makes future cases far cleaner.

One caution: employees have some privacy expectations in genuinely private channels. That affects how you obtained the evidence, rarely whether you can act on serious harassment of a colleague.