Brian Rafferty ingested finasteride, a drug prescribed to him to treat an enlarged prostate. Finasteride is a generic version of Proscar, a drug manufactured by Merck. Some time after he started to take the drug, Rafferty began experiencing harmful side effects. Rafferty immediately stopped taking the drug, but the side effects continued and became more severe. The product label for finasteride warned that there was a potential for such side effects but stated that the side effects would cease if one stopped ingesting it.

Federal law requires that generic drug labels share the same warnings as their brand-name counterparts. Thus, the finasteride label was identical to the Proscar label. During the time that Rafferty was taking finasteride, several studies began to show that the side effects of the two drugs could continue after one stops taking it. Merck allegedly knew about these studies and changed some of its foreign labels to reflect this information, but did not do so in the United States. Thus, the finasteride label also did not reflect this information. Rafferty sued Merck for negligence and failure to warn. Does Merck owe a duty to Rafferty, even though he did not use their product?