CAUSATION: Hardeman v. Monsanto* (U.S. Ninth Circuit Court of Appeals, 19-16636, 19-16708)

This case involves a plaintiff who was diagnosed with non-Hodgkin's lymphoma which he alleged was caused by his use of defendant Monsanto's herbicides. The issue was whether Monsanto's glyphosate-based herbicides such as Roundup was the cause of the plaintiff's illness. Following a trial which included conflicting expert testimony regarding the scientific question at issue, the jury concluded that Roundup was a substantial factor in causing the plaintiff's cancer and that Monsanto should have warned consumers that its herbicides caused cancer. The jury awarded the plaintiff a total of $80 million in damages.  The defendants appealed the jury's verdict.

On December 23, 2019, CMA, along with other amici, filed an amicus brief which illustrates to the court the proper approach to address medical causation in this and other cases that present complex scientific questions – many of which are decided based on physician testimony. The brief points out that the answer to complex scientific questions should be based on accepted scientific evidence and rigorous scientific reasoning, explains the analytical process known to physicians as "differential diagnosis," and argues that the proper analysis for causation should be in terms of but-for or counterfactual causation accomplished by comparing and evaluating hypothetical situations concerning what might have happened such that the crucial causation inquiry is what would have happened. The case is currently pending before the Ninth Circuit Court of Appeals.