How could the consumer prove fault?

By the time the consumer is harmed, it may be very difficult to establish how the defect occurred and whether the manufacturer was at fault. In order to deal with this problem, many systems in the 1970s introduced a reversal of the burden of proof – if the consumer showed that the product had caused her injury, then it was up to the manufacturer to show that he had not been at fault.

In the Fowl Pest case (1968), a vet used defective (non-sterile) vaccine bought from manufacturer on a farmer’s chickens who died. The German Supreme Court held that, to find the manufacturer liable to the consumer for fault under §823 I of the Civil Code, it was sufficient that she showed that there was a defect of breach of a statute designed to protect her. Thereafter, the court would assume that the manufacturer had acted unlawfully, was at fault and the fault had caused the consumer’s injury. The manufacturer could rebut this by showing that he operated a careful system and that the defective product in this case was an odd unit.

French law went further and extended strict liability for the acts of things (art. 1384, para. 1) to products the cause of whose defect had been under the control of the manufacturer.