Under the Food Safety Act 1990, the principal defence is 'due diligence', however it is not a mandatory requirement. This defence enables a food business operator to be acquitted of an offence if they can prove that they had 'taken all reasonable precautions and exercised all due diligence to avoid committing that offence'.
The burden of proof will lie with the defendant they need not establish their case beyond all reasonable doubt, they need only persuade the court that their case is made out on the balance of probabilities. One aspect of 'due diligence' may be the keeping of records which can be used as supportive evidence if taken to task. Some of these records may well include; temperature readings, customer feedback (complaints), training records, pest control reports, reporting of infection requirments for food handlers etc.