market share liability, lead paint litigation, products liability, causation
Over 300,000 young children in America—disproportionately poor and children of color—suffer from childhood lead poisoning. This disease ordinarily is caused by the deterioration of lead paint into flakes, chips, and dust that children ingest or inhale. Victims of childhood lead poisoning have tried to sue manufacturers of lead paint or lead pigment, but they face a seemingly insurmountable obstacle. Traditional tort law requires a plaintiff to prove that a specific tortfeasor caused the harm. This is almost impossible in the lead paint context because the paint that caused the harm usually consists of many layers, applied over the course of as long as a century, now covered up by non-leaded paint. To overcome this obstacle, victims of childhood lead poisoning have invoked the theory of “market share liability.” Market share liability originally was devised in the 1980s to allow recovery by the victims of the generic miscarriage preventative diethylstilbestrol (DES). DES was taken by women whose daughters later developed certain cancers. But the DES daughters could not identify the specific manufacturer whose drug their mothers consumed. The California Supreme Court, in Sindell v. Abbott Laboratories, granted them relief by apportioning liability among DES manufacturers according to each one’s share of the market. Victims of other defective products then urged courts to extend market share liability beyond the DES context. With a few exceptions, such efforts failed because the other products were not “fungible,” i.e., they were not as interchangeable as the generic drug DES. Additionally, DES was taken during a nine-month period, making it relatively easy for courts to determine the market shares of each manufacturer with a reasonable degree of accuracy—not so with other products. Thus, for some twenty years, market share liability lay dormant. In 2004, Allen Rostron published an article that challenged the implicit assumption in market share liability that fungibility meant chemical identity. Indeed, he identified three definitions of fungibility: (1) functional interchangeability, (2) physical indistinguishability, and (3) uniformity of risk. Almost immediately thereafter, the Wisconsin Supreme Court, in Thomas v. Mallett, employed portions of Rostron’s analysis to allow a victim of childhood lead poisoning to proceed to trial under Wisconsin’s variant of market share liability. The extension of market share liability to the lead paint context is problematic. Lead paints, or paints with lead pigment, do not pose a uniform risk of harm because paints with higher concentrations of lead are more harmful than those with less. Additionally, it is impossible, as a practical matter, to determine the market shares of the manufacturers of lead paint and lead pigment given the hundred-year period in which manufacturers have entered, exited, and re-entered the market to be segmented. If market share liability is to apply beyond the DES context, this expansion must be consistent with the policies that gave rise to the theory. We thus propose that application of market share liability be predicated on three requirements: (1) uniform products must pose risk in a uniform manner and to a uniform degree; (2) it must be impossible, as a practical matter, for a victim to trace the harm-causing product back to its specific manufacturer; and (3) courts must be able to ascertain each manufacturer’s market share with a reasonable degree of accuracy.
58 South Carolina Law Review 115 (2006).