Plaintiffs’ burden of proving that a particular defendant caused an asbestos-related injury will become more difficult due to a recent Ohio Supreme Court opinion discrediting the cumulative-exposure theory.

On February 8, 2018, the Ohio Supreme Court ruled in Schwartz, et al. v. Honeywell International, Inc., Slip Opinion No. 2018-Ohio-474, that a plaintiff’s purported cumulative exposure to a variety of asbestos-containing products is insufficient to show that exposure from one defendant’s product was a substantial factor in causing the plaintiff’s asbestos-related injury.

Ohio Revised Code § 2307.96 requires that plaintiffs asserting asbestos causes of action must prove that a particular defendant’s product was a “substantial factor” in causing their injuries. In determining whether an individual’s exposure to a particular defendant’s asbestos was a substantial factor, courts are required to consider the manner, proximity, frequency and duration of the asbestos exposure.

In Schwartz, the court rejected the plaintiffs’ cumulative-exposure theory as a means of proving substantial factor causation. The court rejected the plaintiffs’ commonly asserted claim that every non-minimal exposure to asbestos is a substantial factor in causing individuals’ injuries because each such dose purportedly contributes to a cumulative dose of asbestos exposure, resulting in overall harm.

In rejecting the theory, the court noted that the cumulative-exposure theory considers all of the defendants in the aggregate, which is inconsistent with the individual analysis required by statute; disregards the statutory considerations of manner, proximity, length and duration of exposure; and arbitrarily draws a line between the exposure levels that could be a substantial factor in causing disease and those that could not. The court joined the Sixth and Ninth Circuits and other state courts in holding that the cumulative-exposure theory cannot be relied upon to prove exposure from one defendant’s asbestos-containing product is a substantial factor in causing a plaintiff’s injury.