The plaintiff in Sindell was a young woman who developed cancer as a result of her mother's use of the drug diethylstilbestrol (DES) during pregnancy.

Since the drug was a fungible product and many years had passed, it was impossible for the plaintiff to identify the manufacturer(s) of the particular DES pills her mother had actually consumed.

The doctrine evolved from a line of negligence and strict products liability opinions (most of which had been decided by the Supreme Court of California) that were being adopted as the majority rule in many U.S. states.

Mosk later explained in an oral history interview that the court got the idea for market share liability from the Fordham Law Review comment cited extensively in the Sindell opinion.

[1] Associate Justice Frank K. Richardson wrote a dissent in which he accused the majority of judicial activism and argued that the judiciary should defer to the legislature, whose role it was to craft an appropriate solution to the problems presented by the unique nature of DES.