Can expert affidavits that contradict deposition testimony survive summary judgment? Dierl v. Birkin Explained

In Dierl v. Birkin, the Utah Court of Appeals addressed critical issues surrounding the admissibility of expert witness testimony in medical malpractice cases, particularly when expert affidavits appear to contradict prior deposition testimony.

Background and Facts

Martin Dierl underwent a CT scan after a ski resort injury in February 2015. Dr. Barry Birkin, a radiologist, interpreted the scan as normal, reporting “no intracranial masses.” Nine months later, when Dierl developed neurological symptoms, another physician discovered a large brain tumor that was visible on the original scan. Dierl underwent surgery in December 2015, suffering permanent vision loss and pituitary damage. He sued Birkin for medical malpractice, alleging the delayed diagnosis proximately caused his injuries.

Key Legal Issues

The central issue was whether Dierl’s expert witness affidavits could establish proximate cause for summary judgment purposes. Dierl’s primary expert, Neurosurgeon 1, testified in deposition that he could not state “to a reasonable degree of medical probability” that earlier surgery would have prevented Dierl’s specific injuries. However, in a subsequent affidavit, Neurosurgeon 1 opined that Dierl’s vision loss was greater due to the tumor’s enlargement between February and December 2015. Dierl also sought to introduce testimony from Neurosurgeon 2, disclosed only as a rebuttal expert but offered to establish causation in his case-in-chief.

Court’s Analysis and Holding

The court applied Webster v. Sill to exclude Neurosurgeon 1’s affidavit, holding that when a party takes a clear position in deposition testimony that is not modified on cross-examination, they cannot thereafter raise a genuine issue of fact through a contradictory affidavit unless they provide an adequate explanation for the discrepancy. The court found Neurosurgeon 1’s deposition answers were “clear and unequivocal” and that his affidavit “wholly failed to explain the discrepancy.”

Regarding Neurosurgeon 2, the court applied Utah Rule of Civil Procedure 26(d)(4), which bars the use of untimely disclosed expert witnesses unless the failure is harmless or the party shows good cause. Since Neurosurgeon 2 was disclosed only as a rebuttal expert after the deadline for case-in-chief expert disclosures, and Dierl made no showing of harmlessness or good cause, the testimony was properly excluded.

Practice Implications

This decision reinforces the importance of consistent expert testimony throughout litigation. Practitioners must ensure their experts understand the scope and implications of their deposition testimony, as subsequent contradictory statements may be excluded even if they would create genuine issues of material fact. Additionally, the ruling emphasizes strict adherence to Rule 26 disclosure deadlines—parties cannot rely on rebuttal expert designations to cure deficiencies in their case-in-chief expert disclosures, particularly when essential elements like proximate cause remain unproven.