The Supreme Court has held Morrisons vicariously liable for the thuggery of one of its employees, who followed a customer out to his car where he punched and kicked him.

The assault occurred in March 2008 when Ahmed Mohamud entered the supermarket group’s petrol station kiosk in Small Heath, Birmingham, and asked if he could print documents from a USB stick.

Morrisons’ employee Amjid Khan refused “in a rude manner” and Mohamud protested.

Khan responded in “foul, racist and threatening language” and ordered Mohamud, who has since died from an illness unrelated to his claim, to leave.

Before Mohamud could drive off, Khan opened the passenger door, told him “in threatening words” to never return and punched him on the left temple.

Mohamud got out and walked round to close the passenger door when Khan subjected him to kicks and punches while the victim lay curled up on the forecourt, trying to protect his head.

Khan’s supervisor tried to stop him but Khan ignored his instructions.

Mohamud had done nothing that could be considered aggressive or abusive, according to court documents.

The trial judge dismissed the claim Mohamud brought that Morrisons was vicariously liable for the actions of Khan and the Court of Appeal upheld the decision.

Mohamud appealed and the Supreme Court on Wednesday found Morrisons vicariously liable.

“When this appalling incident happened we were horrified and dismissed Amjid Khan. We then offered a settlement option to Mr Mohamud but he and his legal team wanted to progress a case which involved widening the rules on vicarious liability - where a company can be held liable for the actions of an individual member of staff,” said a Morrisons spokesman.

“While the Supreme Court has not changed the law on vicarious liability, we accept that it has now said we should now pay the previously agreed damages.”

Sarah Ozanne, an employment partner with law firm CMS, said the case did not widen the existing law of vicarious liability but reinforced it.

“The decision is based on the test of close connection between the harm done and the job.”