This book analyses the allocation of the burden of proof in consumer sale cases, in particular the application of the presumption of non-conformity designed to simplify the consumer's duty to supply evidence. It provides detailed information on the notion of non-conformity as found in the Consumer Sales Directive and implemented in Poland, Germany, England and Wales, and the Netherlands and presents a comprehensive analysis of the presumption of non-conformity. The author clarifies whether the presumption of non-conformity constitutes an appropriate tool for simplifying the burden of proof lying with the consumer and whether it provides for a high level of consumer protection necessary for the better functioning of the European Internal Market.