Richard Welge (plaintiff) was putting the cap on a glass jar of Planters peanuts when it shattered, cutting his hand. Welge brought suit against Planters Lifesavers Co. (Planters), the manufacturer of the glass jar, and K-Mart (defendants), where the peanuts were purchased. Welge stated that he was using the jar exactly how it was meant to be used and that he did not somehow damage the jar after he bought it. During pretrial discovery, experts agreed that there was a defect in the jar, but they could not determine where it was or when it came to be. The district court granted the defendants' summary-judgment motion on the ground that Welge did not exclude possible causes of the accident other than a manufacturing defect. Welge appealed.