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Lawyers accustomed to relying on experience-based experts must now make the analytical path explicit. Credibility and cross-examination alone could rescue a thin factual basis or an implicit chain of reasoning. Admissibility is no longer a late-stage checkpoint. It is a threshold gate, and lawyers must plan accordingly from the outset of a case.
In the November 20, 2025 edition of The Legal Intelligencer, Edward Kang writes, “Method, Not Mystique: The Renewed Demands of Rule 702.“
For many years, it was common practice to address expert challenges late in the litigation cycle. Create case themes. Discovery proceeds. Case themes change or develop alongside witness testimony. The Daubert briefing arrives near the end. The expectation was that juries would resolve competing expert views through cross-examination and credibility determinations. That cycle no longer accurately reflects reality in federal courts within the U.S. Court of Appeals for the Third Circuit and throughout the country.
Since the 2023 amendment to Federal Rule of Evidence 702, courts have adopted a more explicit and front-loaded approach to expert admissibility. The rule did not rewrite the familiar elements of qualification, reliability, and fit, but it clarified who bears what burden and when. Trial courts must now ensure, more likely than not, that an expert has not only employed a reliable method but applied that method reliably to sufficient facts or data. Issues that once passed as matters of weight for the jury now receive substantive scrutiny at the admissibility stage.
Lawyers accustomed to relying on experience-based experts must now make the analytical path explicit. Credibility and cross-examination alone could rescue a thin factual basis or an implicit chain of reasoning. Admissibility is no longer a late-stage checkpoint. It is a threshold gate, and lawyers must plan accordingly from the outset of a case.
The Approach Within the Third Circuit
In Slatowski v. Sig Sauer, 2024 WL 1078198 (E.D. Pa. Mar. 12, 2024), aff’d in part, rev’d in part and remanded, 148 F.4th 132 (3d Cir. 2025), the U.S. District Court for the Eastern District of Pennsylvania excluded two causation experts in a firearm-discharge case despite their credentials and experience. The district court found the opinions lacked a reliable analytical bridge, emphasizing that neither expert offered any conclusion that could be subject to testing or specific to the circumstances in which the plaintiff’s pistol fired. The lack of incident-focused methodology and analysis proved fatal under amended Rule 702.
The Third Circuit affirmed. The panel stressed that the “hallmark of Daubert‘s reliability” prong is the scientific method, meaning the “generation of testable hypotheses that are then subjected to the real-world crucible of experimentation, falsification/validation, and replication.” The court noted that a qualified expert must bridge the gap between theory and reality, and the lack of factual context was fatal in this case. Even if the expert testimony was “reliable about whether the [pistol’s] design could have caused an accident,” it needs to be reliable about “whether the design did cause this accident.”
It is worth noting that the court did not characterize this decision as a close call or a matter better left to cross-examination. Instead, it treated the Rule 702 amendment as a clear directive: opinions that lack testable, case-grounded reasoning cannot reach the jury. The ruling signals a practical expectation that plaintiffs must now present a documented analytical path that connects method to facts with precision, not inference or shorthand experience.
The Growing Trend of Demanding Reliable Application of Reliable Methods to Facts
Courts outside the Third Circuit are moving in the same direction. The amended rule and the advisory committee’s commentary have become a touchstone, and courts are citing them to clarify that the sufficiency of basis and reliability of application belong to judges, not juries. Three circuits illustrate this shift.
The Sixth Circuit’s approach is best illustrated by In re Onglyza and Kombiglyze Products Liability Litigation, 93 F.4th 339 (6th Cir. 2024), where exclusion of the plaintiffs’ cardiology expert was affirmed after the court found that, although the expert used “undeniably a reliable methodology,” the opinion was unreliable because it rested on selective data points and inconsistent application of several factors required by the method. The opinion cites the 2023 amendment and emphasizes its “corrective effect:” Rule 702’s recent amendments “were drafted to correct some court decisions incorrectly holding ‘that the critical questions of the sufficiency of an expert’s basis, and the application of the expert’s methodology, are questions of weight and not admissibility.’”
The Ninth Circuit’s decision reveals a similar posture, but with different emphasis. In Engilis v. Monsanto, 151 F.4th 1040 (9th Cir. 2025), the court rejected any presumption of admissibility by noting that “there is no such presumption, as a proponent of expert testimony must always establish the admissibility requirements of Rule 702 by a preponderance of the evidence.” The court affirmed the lower court’s exclusion of expert testimony and granting of summary judgment where the expert failed to provide any “scientifically sound reason” when ruling out a potential cause, thus failing to establish that his testimony was “based on sufficient facts or data.” The Fifth Circuit has been equally direct. Nairne v. Landry, 151 F.4th 666, 705 (5th Cir. 2025), reinforces the point by excluding a statistics expert who failed to explain the method-to-data application.
Across jurisdictions, the pattern is consistent. Courts expect transparent and documented analysis sufficient to show a reliable application of established methods to relevant facts. When some part of the analytical or reasoning chain is missing, courts will exercise their role as gatekeepers and exclude the expert testimony. The cases do not signal hostility to plaintiffs or to experts. They signal a renewed willingness on the part of the courts to enforce Rule 702 as written: reliability must now be demonstrated, rather than assumed.
Practical Guidance for Plaintiffs Attorneys
For plaintiffs lawyers, the shift in expert testimony admissibility is not theoretical. It reorders when and how cases must be built. The admissibility of expert testimony should be treated as a design principle from day one: identify the theory of causation early, map the analytic chain, and assemble the factual record intentionally so that each step is visible and testable. Litigation strategy must align with admissibility demands, rather than assuming that cross-examination will supply what the record lacks.
The amended Rule 702 rewards intentional sequencing. It punishes gaps that emerge only after discovery closes. Ask experts, before engagement if possible, to articulate precisely how their method connects to the facts at issue and what data they will need to apply it reliably. Build discovery around that roadmap. If testing, literature review, or additional medical documentation is necessary, get it early. Document the methodology as a narrative, not merely as a set of citations. Writing it early sharpens the analysis and exposes weaknesses in time to cure them. Treat expert testimony admissibility as architecture, not defense. In doing so, plaintiffs will not only meet the demands of Rule 702 but also strengthen the merits of their cases in the process.
Edward T. Kang is the managing member of Kang Haggerty. He devotes the majority of his practice to business litigation and other litigation involving business entities. Contact him at ekang@kanghaggerty.com.
Reprinted with permission from the November 20, 2025 edition of “The Legal Intelligencer” © 2025 ALM Global, LLC. All rights reserved. Further duplication without permission is prohibited. Request academic re-use from www.copyright.com. All other uses, submit a request to asset-and-logo-licensing@alm.com. For more information visit Asset & Logo Licensing.