From “Liberal Thrust” to Rigorous Gate-Keeping: Delaware Supreme Court Aligns D.R.E. 702 with Federal Rule 702 and Mandates Product-Specific Causation — Commentary on In re Zantac (Ranitidine) Litigation

1. Introduction

The Delaware Supreme Court’s en banc decision in In re Zantac (Ranitidine) Litigation, No. 255, 2024 (Jul. 10 2025), rewrites the playbook for the admissibility of expert testimony in Delaware. The Court reversed a Superior Court order that had allowed ten plaintiff experts to testify that the heartburn drug Zantac (ranitidine) causes ten cancers. Nearly 75,000 individual claims hinged on that ruling.

Two core issues animated the appeal:

Whether Delaware’s Rule of Evidence 702 (“D.R.E. 702”) presumptively favors admission of expert testimony (the “liberal thrust” approach) or imposes a true gate-keeping burden aligned with the federal rule.
Whether, at the general-causation stage, experts may extrapolate from studies on an alleged toxic agent (NDMA) or must link the specific product (ranitidine) to the claimed injuries.

The Supreme Court answered both in favor of a stricter, product-focused standard, thereby erecting a significant barrier to mass-tort expert evidence in Delaware and clarifying that D.R.E. 702 equals, not exceeds, its federal counterpart.

2. Summary of the Judgment

Key holdings:

No Presumption of Admissibility. The Superior Court erred in applying a “liberal thrust favoring admission.” Under D.R.E. 702 (mirroring Federal Rule 702 as amended in 2023), the proponent bears the burden—by a preponderance of the evidence—of demonstrating both sufficiency of the data and reliability of methodology and application.
Product-Specific Causation Required. General-causation experts cannot rely solely on studies of NDMA in food, air, or occupational settings without scientifically bridging the exposure in those studies to NDMA exposure from ranitidine tablets.
Gate-Keeping Is Judicial, Not Jury Work. Challenges that go to sufficiency or reliability are questions of admissibility, not of “weight” for a jury.
Result. All ten plaintiff expert opinions were excluded; the Superior Court order was reversed and remanded, threatening the viability of tens of thousands of claims.

3. Analysis

3.1 Precedents Cited and Their Influence

Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993) — foundational gate-keeping framework; Delaware had adopted it in M.G. Bancorp. v. Le Beau.
Fed. R. Evid. 702 (2023 amendments) — emphasized that admissibility questions are governed by Rule 104(a)’s preponderance standard; Delaware Supreme Court treated advisory-committee notes as persuasive.
In re Asbestos Litigation, 911 A.2d 1176 (Del. Super. 2006) & Gen. Motors Corp. v. Grenier, 981 A.2d 531 (Del. 2009) — established that experts must connect the disease-causing agent to the exposures created by the defendant’s product.
Barrera v. Monsanto Co., 2019 WL 2331090 (Del. Super.) — cited below for the proposition that Delaware eschews “threshold dose.” Supreme Court clarified Barrera did not alter D.R.E. 702 burdens.
Tumlinson v. Advanced Micro Devices, 81 A.3d 1264 (Del. 2013) and Bowen v. DuPont, 906 A.2d 787 (Del. 2006) — reiterated requirement that methodology be reliably applied.

3.2 Core Legal Reasoning

Misapplication of “Liberal Thrust.” The Supreme Court traced the phrase to Daubert but explained it merely rejected the Frye general-acceptance test. It never created a presumption that any expert opinion crossing the threshold of relevance should reach a jury.
D.R.E. 702 = Federal Rule 702. The decision dismantles any perceived Delaware-specific laxity. Delaware’s rule was amended twice to track the federal language; courts must therefore apply the same rigorous analysis, including recent federal clarifications.
Weight vs. Admissibility Error. The Superior Court discounted methodological criticisms—e.g., “cherry-picking,” non-statistical significance, ignoring contrary epidemiology—as matters of weight. Supreme Court held those go to admissibility when they undermine sufficiency or reliability.
Product-Agent Bridge Required. Citing In re Asbestos, the Court required a “reliable bridge” between NDMA exposure in non-product studies and exposure from ranitidine. Plaintiffs offered only one such bridge (Dr. Sawyer’s dose-conversion) and it was methodologically flawed.

3.3 Potential Impact

Mass-Tort Strategy. Plaintiffs choosing Delaware for friendly evidentiary standards may now face the same hurdles present in federal MDLs.
Expert Practice. Experts must be prepared to quantify dose, explain study selection, and reconcile contrary data. “I’ll let the jury weigh it” is no longer viable at the admissibility stage.
Trial Court Procedure. Delaware judges must make explicit findings on each Rule 702 element and may conduct Daubert hearings resembling mini-trials in complex cases.
National Persuasive Value. Because the Court relied heavily on the 2023 federal amendments, other state courts may cite Delaware as aligning state rules with the new federal clarity.
Immediate Case Effect. Unless plaintiffs find admissible general-causation evidence, the 75,000 ranitidine claims in Delaware will likely be dismissed on summary judgment.

4. Complex Concepts Simplified

D.R.E./F.R.E. 702 — The evidence rule governing expert testimony. It asks: (1) Is the evidence helpful? (2) Are the facts/data sufficient? (3) Is the method reliable? (4) Was the method reliably applied here?
Gate-Keeping — The judge’s duty to screen expert evidence before it reaches the jury.
General vs. Specific Causation
- General: Can substance X cause disease Y in humans at all?
- Specific: Did substance X actually cause this plaintiff’s disease Y?
“Weight, Not Admissibility” Error — Courts sometimes say flaws affect credibility, not admissibility. The Delaware Supreme Court clarifies that when flaws undermine the Rule 702 elements, exclusion is mandatory.
Product-Agent Bridge — If a product contains a carcinogen, the expert must scientifically show that the exposure level from the product matches exposures that cause disease in the referenced studies.

5. Conclusion

The Delaware Supreme Court’s decision in In re Zantac makes two enduring pronouncements:

Delaware courts must apply a rigorous, burden-shifting analysis identical to post-2023 Federal Rule 702. There is no “liberal thrust” presumption.
General-causation experts in product-liability cases must tether their opinion to the product itself; reliance on studies of a toxic agent alone is insufficient absent a scientifically reliable bridge.

By enforcing these standards, the Court curtailed expansive expert opinions in mass-tort litigation and reinforced judges’ roles as scientific gatekeepers. Practitioners should expect more demanding Daubert hearings, detailed judicial findings, and—in the absence of solid product-specific data—higher dismissal rates at the threshold stage.