Defence whereby a ‘producer’ can avoid Consumer Protection Act 1987 liability. If, at the time of supply, the state of scientific and technical knowledge was not such that a producer of similar products might have been expected to discover the defect if it had existed while there were products under his control, there will be no liability under the Act. It is no defence to show that the producer was unaware of the risk because of no prior accidents. The defence only applies when there has been some technical or scientific advance since the time of supply that subsequently enable the defect to be identified (Abouzaid v. Mothercare (UK) Ltd (2001)). The producer must show that the defence applies.