Williams v. U.S. Dist. Court

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Justia Opinion Summary

This case involved consolidated petitions for writs of mandamus challenging district court rulings regarding the admissibility of expert testimony. The petitions arose out of two separate actions resulting from an outbreak of heptitis C at an endoscopy clinic. Plaintiffs sued defendants, pharmaceutical companies, for strict products liability. The Supreme Court held that (1) a nurse can testify regarding matters within his or her specialized area of practice but not as to medical causation unless he or she has obtained the requisite knowledge, skill, experience, or training to identify cause; and (2) the standard for defense expert testimony regarding medical causation differs depending on how the defendant utilizes the expert's testimony. When a defense expert traverses the causation theory offered by the plaintiff and purports an independent causation theory, the testimony must be stated to a reasonable degree of medical probability pursuant to Morsicato v. Sav-On Drug Stores. However, when a defense expert's testimony of alternative causation theories controverts an element of the plaintiff's prima facie case where the plaintiff bears the burden of proof, the testimony must only be relevant and supported by competent medical research.