## Facts

- A pregnant patient presented to a hospital emergency room; plaintiffs alleged negligent care led to a premature delivery, and the infant died two days after birth from complications linked to incomplete development.
- Plaintiffs sued the hospital and physicians under Puerto Rico tort law for medical malpractice and under EMTALA, alleging the hospital failed to follow its own screening protocols.
- To prove both liability theories, plaintiffs relied on a single medical expert, an obstetrician–gynecologist with long clinical and teaching experience who had stopped practicing and worked primarily as a plaintiffs’ expert witness.
- At trial, after plaintiffs presented fact witnesses, defendants moved to exclude the expert; the district court excluded him based on perceived pro-plaintiff bias.
- Plaintiffs then rested; defendants sought judgment as a matter of law under Federal Rule of Civil Procedure 50(a), which the district court granted due to the absence of expert proof after exclusion.

## Issues

1. Whether the district court abused its discretion by excluding plaintiffs’ only expert under Federal Rule of Evidence 702 based solely on perceived generalized pro-plaintiff bias, without identifying reliability or methodology defects.
2. Whether the district court properly granted Rule 50(a) judgment as a matter of law after excluding the expert testimony necessary to establish malpractice and EMTALA elements.

## Decision

- The First Circuit held the district court abused its discretion by excluding the expert based solely on perceived bias unrelated to methodology or reliability.
- The court ruled that generalized partisanship is ordinarily a matter for cross-examination and for the jury’s credibility determination, not a ground for categorical exclusion.
- Because the expert’s exclusion eliminated essential proof and directly led to the Rule 50(a) ruling, the judgment as a matter of law could not stand.
- The First Circuit vacated the judgment and remanded for a new trial with the expert testimony admitted, subject to proper impeachment and cross-examination.

## Legal Principles

- Federal Rule of Evidence 702 and Daubert gatekeeping focus on relevance and reliability, including the soundness of the expert’s methodology and the basis for the opinion.
- An expert’s general tendency to testify for one side, financial incentive, or affiliation with a party’s counsel typically goes to weight and credibility, not admissibility.
- Excluding expert testimony solely due to generalized bias, without identifying methodological unreliability or an inadequate factual foundation, is an abuse of discretion.
- When a case’s required elements depend on expert testimony, an erroneous exclusion that produces an evidentiary void is prejudicial and may require vacatur of a resulting Rule 50 judgment.

## Conclusion

The First Circuit held that perceived pro-plaintiff bias alone is not a valid basis to exclude an otherwise qualified expert under Rule 702, vacated the judgment entered after the exclusion, and remanded for a new trial where bias could be tested before the jury through cross-examination and argument.


Cruz-Vázquez v. Mennonite Gen. Hosp., Inc., 613 F.3d 54 (1st Cir. 2010)