Expert Testimony Admissibility: Addressing Obvious Alternative Causes Under Rule 702

1. Introduction

In Faison-Williams v. United States (2d Cir. 2025), the Second Circuit addressed two critical issues under the Federal Tort Claims Act (FTCA): the scope of administrative‐claim exhaustion for medical malpractice allegations; and the proper standard for admitting expert testimony under Federal Rule of Evidence 702 when a medical causation opinion faces alternative explanations. The panel—Judges Sack, Robinson, and District Judge Koeltl—vacated the district court’s grant of summary judgment and exclusion of the plaintiff’s causation expert, and remanded for further proceedings.

Parties and Background: Plaintiff Natasha Faison-Williams is a veteran who sued the United States under the FTCA, alleging malpractice by her VA neurosurgeon, Dr. James Stone. After undergoing two spinal operations (anterior cervical fusion and thoracic microdiscectomy), she suffered an epidural hematoma and a range of neurological deficits. The district court excluded her expert’s causation testimony as unreliable and entered summary judgment for the government. Faison-Williams appealed.

2. Summary of the Judgment

The Second Circuit’s summary order reached three principal conclusions:

Jurisdiction under the FTCA: The panel held that Faison-Williams’s one‐page administrative claim—alleging deviation from the standard of care in performance of the thoracic surgery—was sufficiently specific to trigger agency investigation into whether the procedure was indicated. The court therefore confirmed subject‐matter jurisdiction.
Standard for Rule 702 Reliability: The panel reaffirmed that under Rule 702, district courts act as gatekeepers assessing whether an expert’s methodology is reliable and relevant. One recognized reliability factor is whether the expert “adequately accounted for obvious alternative explanations.”
Improper Exclusion of Causation Testimony: Although an expert need not rule out every imaginable alternative, the district court here set the bar too high—requiring categorical exclusion of all alternatives. Moreover, Dr. Zonenshayn had, in fact, offered non-conclusory, experience‐based reasons for rejecting each obvious alternative cause (cervical disease, preexisting bladder issues, psychological overlay). Excluding his testimony was an abuse of discretion. The court vacated and remanded.

3. Analysis

3.1. Precedents Cited

28 U.S.C. § 2675(a), McNeil v. United States (508 U.S. 106 (1993)) – FTCA’s jurisdictional “presentment” requirement and exhaustion.
Johnson v. United States (788 F.2d 845 (2d Cir. 1986)) – One‐page administrative claims may suffice if they allow “reasonably thorough investigation.”
Fed. R. Evid. 702 & Advisory Committee Notes (2000) – The gatekeeper function and the “obvious alternative explanations” factor.
Amorgianos v. National Railroad Passenger Corp. (303 F.3d 256 (2d Cir. 2002)) – Abuse‐of‐discretion review of expert admissibility and recognition that reliability, not credentials alone, controls.
Kumho Tire Co. v. Carmichael (526 U.S. 137 (1999)) – District courts may exclude expert testimony despite high qualifications if methodology is unreliable.

3.2. Legal Reasoning

The court’s reasoning unfolds in two strands:

3.2.1. FTCA Presentment and Jurisdiction

Under § 2675(a), a claimant must present the claim to the appropriate federal agency, providing enough detail “as to the basis of the claim, the nature of claimant’s injuries, and the amount of damages sought” so that the agency can investigate and consider settlement. Faison-Williams’s administrative form alleged negligence in scheduling and performing the thoracic surgery. The panel reasoned that any agency investigation into a malpractice performance claim would necessarily review the indication (decision‐making) for that surgery as well, satisfying exhaustion.

3.2.2. Rule 702 Reliability and “Obvious Alternatives”

Rule 702 requires that an expert’s methods be reliable and properly applied. The Advisory Committee’s Notes identify the failure to address obvious alternative explanations as a reliability defect. The district court—citing that factor—concluded Dr. Zonenshayn had not “ruled out” cervical disease, prior bladder issues, or psychological causes, rendering his opinions unreliable. The Second Circuit found two errors:

The district court elevated the requirement into a categorical “rule‐out” test, demanding that the expert demonstrably exclude every alternative rather than adequately address them.
In fact, Dr. Zonenshayn provided detailed, nonconclusory reasons—drawn from imaging, symptom timing, and urodynamic studies—why each alternative did not fit the patient’s clinical picture.

Because the exclusion of an expert’s entire causation testimony was “manifestly erroneous,” the court held that the district court abused its discretion and that summary judgment could not stand without that key evidence.

3.3. Impact

This decision clarifies and limits the “obvious alternative explanation” inquiry under Rule 702. Experts need not discount every hypothetical cause; they must demonstrate reasoned, experience-based analysis of plausible alternatives. For FTCA claimants, the case confirms that broad‐based malpractice allegations can suffice to exhaust remedies when they implicate both performance and decision‐making. More broadly, trial courts are reminded not to conflate the sufficiency of expert reasoning with the merits of the opinion—Gatekeeping must not become a disguised merits adjudication.

4. Complex Concepts Simplified

FTCA Presentment: Like an administrative “heads-up” that tells the government what went wrong, so it can investigate before a lawsuit.
Epidural Hematoma: A collection of blood pressing on the spinal cord, which may cause leg weakness, numbness, or bladder/bowel dysfunction.
Cervical vs Thoracic Myelopathy: Compression of the spinal cord in the neck (cervical) or mid‐back (thoracic). Different levels produce different patterns of weakness and sensory loss.
Conversion Disorder (Psychological Overlay): A condition where symptoms (e.g., paralysis, sensory loss) have a psychological rather than a clear organic cause.
Rule 702 Gatekeeper Role: Judges decide if an expert’s methods and application are reasonable enough to help the jury, not whether the jury should believe the expert.

5. Conclusion

Faison-Williams v. United States reaffirms: (1) a broad administrative claim can cover both surgical performance and indication for surgery under the FTCA; and (2) expert testimony under Rule 702 must address obvious alternative causes with reasoned analysis but need not exclude every theoretical possibility. The Second Circuit’s vacatur and remand underscore that reliability review demands careful attention to the expert’s methodology—not a premature merits decision. This guidance will shape medical‐malpractice litigation and Daubert-style challenges in federal courts nationwide.