Food safety legislation requires that food businesses must not ‘sell to the purchaser’s prejudice any food which is not of the nature, substance and quality demanded by the purchaser’. Therefore if a customer requests a meal that doesn’t contain a particular food and the food business operator gives them a meal that does contain it, then this could lead to prosecution. Legislation also prohibits ‘unsafe’ food being placed on the market. A dish is deemed ‘unsafe’ if it contains an ingredient that a predisposed person is allergic to, even though it is safe for most other people.