With two billion users globally, the use of WhatsApp at work is probably here to stay but, as former Prime Minister Boris Johnson and other leaders have discovered, its use is not without its perils.

The Covid public inquiry brought a host of concerns into sharp relief in terms of the appropriateness and safety of using WhatsApp in a professional setting. The blurring of lines between personal and work life means employers and employees should proceed with caution.

The legal and HR implications can be considerable; one business which failed to include an absent employee in a work-related WhatsApp group chat was deemed to have discriminated against the worker, resulting in an award of £134,000 to the member of staff.

People perceive WhatsApp to be more private than email, but these messages can easily be used as evidence in tribunals and courts.

Employers must navigate whether they can use WhatsApp messages for disciplinary action without violating privacy rights under Article 8 of the European Convention on Human Rights.

Example: the Police Service of Scotland relied on WhatsApp messages as evidence in misconduct proceedings against a police officer; the court ruled the police did not breach privacy or human rights, given the public accountability of the officers.

What is clear is that the law requires a legitimate aim, proportionate to a pressing social need; employers should be aware that WhatsApp messages are subject to evaluation based on the specific circumstances of each case.

Another issue with WhatsApp is its potential to disrupt employees’ ability to switch off outside of work. Employees without a work phone can feel obligated to provide personal numbers to colleagues and professional contacts, making them constantly reachable. This perpetuates an unwelcome "always on" work culture, which can impact mental health, potentially leading to claims for stress and breach of the Working Time Regulations. Indeed, the new UK Government plans to introduce a "right to switch off" from work outside working hours.

A report by Ring Central found that 23% of British workers feel anxious receiving notifications outside of work, rising to 27% among younger workers. This reinforces the considerable HR concerns over this growing practice, and there is little doubt the rise of WhatsApp is a contributing factor.

With this in mind, employers should establish clear policies and train staff in appropriate use, and be clear on the consequences of breaches. This would mitigate risks and, in some cases, could free employers from liability in terms of WhatsApp use. Many workplace policies go further, discouraging contact outside office hours unless previously agreed to respect a healthy work-life balance. Others urge the use of work phones only for professional communication.

More widely, having such policies in place are likely to make staff more aware that work-related messages on personal devices might be recoverable during investigations, prompting more caution in communications overall.

While it is easier to delete an ill-judged WhatsApp message off the recipient’s device than it is to recall an email, anything that encourages work colleagues to ‘think before sending’ serves us all well.

Robin Turnbull is a director at Anderson Strathern and a specialist in employment law

Agenda is a column for outside contributors. Contact: agenda@theherald.co.uk