This book analyses the allocation of the burden of proof in consumer sale cases. Particularly, it investigates the application of the presumption of non-conformity designed to simplify the consumer’s duty to supply evidence. It includes the description of general topics of the burden of proof in Poland, Germany, England and Wales, and the Netherlands. It provides detailed information on the notion of non-conformity as found in the Consumer Sales Directive and implemented in the mentioned Member States. Finally, it presents the comprehensive analyses of the presumption of non-conformity. It investigates the conditions for the application of the presumption, the existence of non-conformity within six months from the time of delivery of goods. It continues with the seller’s options to rebut the presumption. Finally, it discusses the exclusion criteria of the presumption. This book offer answers on whether the presumption of non-conformity constitutes an appropriate tool 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 Internal Market.