Thomas Bockrath (plaintiff) worked for Hughes Aircraft Company (Hughes) from 1973 to 1994. Bockrath developed cancer while working for Hughes. Bockrath sued at least 55 defendants, including the manufacturers of many common products like WD-40 and rubber cement. The complaint alleged that: (1) Bockrath had been exposed to most and perhaps all the products, (2) all the products were used or improperly stored at the Hughes plant, (3) Bockrath had inhaled or had skin contact with all the products, and (4) the chemicals and chemical ingredients in the products produce carcinogenic effects. Two previous complaints were dismissed, and Bockrath filed a second amended complaint. The defendants demurred or moved to dismiss the second amended complaint as well, alleging that Bockrath had not adequately explained how the products caused Bockrath’s cancer. The trial court granted the motion to dismiss without leave to amend, and Bockrath appealed. The California Court of Appeal affirmed, and Bockrath petitioned the California Supreme Court for review.