In Cruz-Vasquez v. Mennonite General Hospital, Inc., 613 F.3d 54 (1st Cir. 2010), plaintiffs sued a hospital and two physicians in the United States District Court for the District of Massachusetts, asserting medical malpractice and Emergency Medical Treatment and Active Labor Act claims after their daughter died two days after her premature birth.

At trial, plaintiffs proffered the expert testimony of a boardqualified— but not board-certified—physician in the fields of obstetrics and gynecology. Due to health issues, the physician had stopped seeing patients a number of years earlier. Since that time, he had served as an expert witness in approximately 150 medical malpractice cases, primarily for plaintiffs, and was collaborating with the plaintiffs’ counsel to give lectures on issues of health law. After holding a hearing pursuant to Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), which requires that expert testimony be shown to be reliable in order to be admitted, in response to an oral motion by defendants, the court excluded the physician’s testimony on the ground that he was biased in favor of plaintiffs in medical malpractice cases. The court also found the physician could be excluded from testifying based on plaintiffs’ failure to furnish defendants with his up-to-date curriculum vitae. The court then ruled that without the expert plaintiffs lacked evidence to support their claims and granted defendants’ motion for judgment as a matter of law.

On plaintiffs’ appeal, the United States Court of Appeals for the First Circuit first observed that the “overarching subject” of a trial court’s inquiry when assessing proposed expert testimony is the scientific validity of the testimony. By focusing its inquiry on the expert’s potential bias, as distinguished from his specialized training or knowledge, the district court’s reasoning had nothing to do with the scientific validity of the expert’s opinion. Considerations such as the expert’s financial interest in the outcome of a case, his bias towards plaintiffs or whether he was currently seeing patients went to his testimony’s probative weight, not admissibility. The court also noted that specific credentials, such as a current board certification, were not required for an expert to be qualified to testify, and that defendants were not prejudiced by plaintiffs’ production of the physician’s outdated curriculum vitae.

The court then explained that the physician’s specialized knowledge – namely his medical training and experience in the field of obstetrics and gynecology and whether it would assist the factfinder better to understand a fact in issue – was the appropriate field of inquiry for the district court’s expert gatekeeping function under Daubert. By deviating from that field and excluding the expert based on potential bias, the court had invaded the province of the jury and abused its discretion. The appellate court therefore vacated the judgment for defendants and remanded for further proceedings.