In Moeller v. Garlock Sealing Technologies, No. 09-5670, the Sixth Circuit clarified the standard for expert testimony on causation under its “substantial factor” test.  As a pipefitter, the plaintiff regularly tore out asbestos insulation and worked with the defendant’s asbestos gaskets.  The gaskets were dangerous when removed, but did not release asbestos when installed.  The plaintiff’s expert testified that the asbestos exposure from removing gaskets greatly exceeded OSHA guidelines, and that this exposure contributed to the plaintiff’s mesothelioma.  In dissent, Judge Moore found this evidence permits the conclusion that the gaskets were a substantial cause of the disease.

The majority disagreed.  The opinion, written by Judge Batchelder, found that testimony that the gaskets contributed to the disease did not prove the gaskets were a “substantial factor” as required by Kentucky law.  It also rejected the plaintiff’s claim that the jury could infer that the gaskets were a substantial factor under Lindstrom v. A-C Product Liability Trust, 424 F.3d 488 (6th Cir. 2005).  The opinion held that Lindstrom requires a “high enough level of exposure” to make causation “probable” or “more than conjectural,” finding that the plaintiff failed to quantify his exposure from the gaskets because there was no proof regarding how frequently he removed the gaskets.

That could be an impossible standard of causation, given the difficulty of quantifying a particular exposure from many years ago.  But Judge Batchelder softened the holding by noting that the exposure from the insulation was “thousands of times greater.”  She concluded that, “[o]n the basis of this record, saying that exposure to Garlock gaskets was a substantial cause of Robert’s mesothelioma would be akin to saying that one who pours a bucket of water into the ocean has substantially contributed to the ocean’s volume.”

Judge Guy’s concurring opinion noted that the jury’s inconsistent verdicts presented an additional ground for reversal.  He argued that, under Kentucky law, the jury’s finding against strict liability for failure to warn was inconsistent with its finding that Garlock had negligently failed to warn.