April Fool's Day is traditionally the day set aside for harmless pranks and practical jokes - but what happens when employees decide to exercise their mischievous streak in the workplace?

Humour is subjective; one person's harmless joke could be another's harassment. Pranks and jokes between employees can get out of hand leading to complaints of misconduct, bullying and discrimination. Not only could an employer be left to manage the internal repercussions of such behaviour but they also risk litigation.

When practical jokes go wrong

One example of an incident supposedly intended to be a practical joke that turned into something far more serious is the case of Otomewo v Carphone Warehouse Ltd.

In this case, two employees took a manager's phone without his permission and updated his Facebook status to say 'finally came out of the closet, I am gay and proud.' His colleagues knew that he was not gay. The manager brought a claim and the employees' conduct was held by an employment tribunal to constitute sexual orientation discrimination.

This case also demonstrates that a heterosexual employee may be subjected to sexual orientation discrimination even if the harasser knows that they are not gay.

One particularly sensitive area is age. Workplace banter focused on older or younger workers is common place but can lead to discrimination allegations, even if someone appears to tolerate teasing they may still be able to successfully claim at tribunal.

Constructive dismissal

If an employee complains or raises a grievance about a supposed joke or prank, an employer must investigate it promptly and take action, where appropriate. Failure to take a grievance seriously or take action to prevent any on-going behaviour could entitle an employee to resign and claim constructive dismissal.

Employer's vicarious liability

If tribunal proceedings are brought by an employee who has been the subject of an inappropriate workplace prank or joke by their co-workers, employers can, if the actions were carried out 'in the course of their employment', find themselves vicariously liable for the actions of their employees. As compensation for discrimination is potentially unlimited this could be expensive.

In Otomewo the employer was held to be vicariously liable for the acts of its employees as the Facebook entries had been posted in the course of employment, the employees' actions took place during working hours and the dealings were between staff and a manager.

Liability will not be imposed if the employer can show that the employee(s) in question were acting on a 'frolic of their own'.

In the 2015 case of Graham v Commercial Bodyworks Ltd the Court of Appeal (CA) held that an employer could not be held liable for injuries caused by a prank gone wrong in the workplace after one employee set fire to another's overalls during 'horseplay'. The CA concluded that 'frolicsome but reckless conduct' cannot normally said to have occurred in the course of employment, meaning it was inappropriate to impose liability on the employer in this case.

However, each case will turn on its own facts and, following the recent Supreme Court decision in Mohamud v WM Morrison Supermarkets plc employers may find it harder to argue an employee was on a frolic of their own.

Demonstrating an active commitment towards combating inappropriate behaviour in the workplace through training and appropriately communicated policies will assist employers in defending vicarious liability claims.

Tips for employers

  • Don't turn a blind eye to an incident simply because it occurred on 1 April and is labelled a prank or joke. Deal with any unacceptable employee conduct in the same manner as you would do so if it occurred on any other day
  • If an employee comes to you complaining that they have had a trick played on them, deal with it efficiently and follow your relevant grievance and/or dignity at work policies. If a decision is made to discipline an employee as a result of their actions follow your own disciplinary procedure at all times
  • Remember that whether the prank or joke is considered offensive or not is a subjective test. This means that if an employee who is the focus of joke takes offence and raises a grievance or even brings an Employment Tribunal claim, it will be no defence for the joker that no offence was intended
  • Take all reasonable steps to prevent inappropriate workplace pranks or jokes from occurring in the first place. Ensure the right policies are in place and up-to-date and ensure all staff are aware of and trained on these policies.