The eggshell skull rule (explained correctly above) applies in civil claims. You do not have to prove any crime - you cannot bring a prosecution for a criminal offence yourself anyway. You could bring a claim against the catering company (who are vicariously liable for the negligent/malicious actions of their employee) for personal injury. Personal injury can mean physical and/or mental injury. On the facts above you would be bound to succeed if you could prove the basic facts, although it would not be worth very much in damages.