Cox -v- Ministry of Justice[2016] UKSC 10

Mr A M Mohamud (in substitution for Mr A Mohamud (deceased) -v- WM Morrison Supermarkets plc [2016] UKSC 11

The Supreme Court has handed down two long-anticipated judgments dealing with vicarious liability. The first (Cox) considers the position of the defendant where a prisoner committed a negligent act whilst working within the prison kitchen.  The second case (Mohamud) considers the position of a defendant whose employee criminally assaulted an innocent customer. The cases consider different aspects of the law of vicarious liability but the Supreme Court has handed down its judgments concurrently and intends them to be complementary to each other. The cases do not dramatically alter or extend the current law; rather, they provide further evolution and clarification of the principles which impact a huge range of potential defendants operating across a multitude of sectors. 

The law

A finding of vicarious liability requires consideration of:

  1. The relationship between the primary wrongdoer and the person alleged to be liable; and 
  2. Whether there is a sufficiently close connection between the wrong doing and the employment, so that it will be fair and just to hold the employer vicariously liable.

Cox focuses on the first stage of that test, Mohamud on the second. This two-stage test stems from a 2001 House of Lords case, Lister -v- Hesley Hall Ltd

The cases

Susan Elaine Cox -v- Ministry of Justice

The claimant was injured while working as catering manager at HMP Swansea. The accident was caused by the negligence of a prisoner carrying out paid work under her supervision in the prison kitchen. The claimant argued that the defendant was vicariously liable for the prisoner’s negligent act.   

At trial, vicarious liability was not established but that decision was reversed on appeal. The defendant appealed to the Supreme Court arguing that the relationship between the Prison Service and prisoners is fundamentally different from that between a private employer and employee and as such the first limb of the test set in Lister could not be satisfied.

Ahmed Mohamud -v- WM Morrisons Supermarkets plc

The claimant had driven into the defendant’s petrol station to check his tyre pressure. He then went into the kiosk to ask if it was possible to print some documents from a USB stick. The petrol station attendant refused, and when the claimant protested, he was subjected to racist abuse and threats. When the claimant returned to his car, the attendant followed him, opening the passenger door and punching him in the head. When the claimant got out of the car, the attendant brutally attacked him, telling him to leave and never to come back to the premises.  

At trial and on appeal the defendant escaped a finding of vicarious liability. The mere fact that a sales assistant was required to interact with customers in the course of his employment was not sufficient to make his employer vicariously liable for any assault he might inflict on a customer. Some feature going beyond interaction between the employee and the victim was required in order to fix the employer with liability and therefore satisfy the ‘close connection’ test.

The claimant appealed to the Supreme Court, arguing that a new test of vicarious liability was required to replace the ‘close connection’ test. In the alternative, the claimant argued that the test was met because the employee was acting within a field of activities assigned to him in dealing with claimant.

The decisions


The Supreme Court dismissed the defendant’s appeal, finding that it was vicariously liable for the prisoner’s negligent act.  

The defendant argued that the primary purpose of the Prison Service is to support the rehabilitation of prisoners and not to advance the business or enterprise of the prison. It does not seek to make a profit and the prisoners have no interest in furthering the objectives of the prison. This argument was rejected.  Prisoners are integrated into the operation of the prison and the activities which they carry out (including feeding the other prisoners) are an integral part of furthering the prison’s aims. 

It was held to be irrelevant that the prisoners were paid less than the minimum wage, as the pay was intended to motivate them. The prisoner was required to undertake useful work for nominal wages as part of his sentence, which strengthened the case for imposing vicarious liability.

The defendant also argued that it was always necessary to ask whether it was fair, just and reasonable to impose vicarious liability. It relied on the fact that the Prison Service acts in the public interest and any liability would need to be paid out of limited public funds. The Court disagreed, confirming that where the criteria were met it should not generally be necessary to re-assess the fairness, justice and reasonableness of the result. In any event, even if this question were to be asked in this case, the conclusion was not to be regarded as unreasonable or unjust. 


The Supreme Court allowed the claimant’s appeal, ruling that the defendant was vicariously liable.

The claimant sought to replace the ‘close connection’ test with a broader test of ‘representative capacity’. That proposed new test was rejected. However, the appeal was allowed.  The Supreme Court held that the Lister approach remains appropriate. While the current test may be imprecise, that imprecision is inevitable in this area of the law.

In making its decision the Supreme Court considered:

  • The nature of the employee’s job, its function and the ‘field of activities’ entrusted by the defendant to the employee. This factor is to be considered broadly. 
  • Whether there was a sufficient connection between the employee’s position and his wrongful conduct for the employer to be held liable under the principle of social justice.

On these issues the Supreme Court found that the employee had interacted with the claimant, refusing his request to print documents in an inexcusable way, and that interaction was within the field of activities assigned to him. When the employee stepped onto the forecourt he was following up what he had said to the claimant from behind the counter as part of an unbroken string of events, described  by Lord Toulson as a ‘seamless episode’. He could not be said to have metaphorically removed his uniform at that point. When the employee told the claimant never to come back to the petrol station, opening the car door to do so, this was not a personal issue. Rather the employee was purporting to act in the course of his employer’s business. The way the employee did so was a gross abuse of position but it was in connection with the business in which he was employed to serve customers. Ultimately the defendant had entrusted the employee with his position and it was just and reasonable that the defendant should be held liable for his abuse of it. The employee’s motive – stated to be personal racism – was irrelevant. 

Future impact

As indicated, the decisions in these cases do not represent an extension of the current law. Rather, they evolve and clarify some aspects of it. In Cox there is reinforcement of the fact that an employee/employer relationship does not have to include the payment of a wage and that it is not necessary for the activities being carried out by the defendant to be of a commercial nature or for there to be profit involved. Arguments by the defendant that a decision against it in this case could open the floodgates to more claims, resulting in (1) an impact on the public purse and (2) prisons adopting an unduly cautious approach to the tasks that prisoners were encouraged to do, were given short shrift.   

Mohamud emphasises the range of considerations at play in deciding whether an employer will be liable for the criminal acts of its employees, along with those, such as motive, which are irrelevant. It potentially makes it more difficult for employers to distance themselves from the actions of their employees where there is a connection, no matter how remote that might seem, to their job role.