Category: Expert Admissibility

Third Circuit Confirms Correlation Still Does Not Prove Causation

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A recent Third Circuit decision is a useful and quotable reminder that temporal correlation is not enough to prove causation.

Causation is an indispensable element of any product liability action. It is the same in pharmaceutical third-party payor (TPP) class actions, where it is often the element most likely to defeat class certification. Unsurprisingly, plaintiffs often employ creative workarounds in an effort to sidestep obvious causation problems. In In re Avandia Marketing, Sales Practices and Products Liability Litigation, — F.4th —, 2026 WL 2093904 (3d Cir. July 21, 2026), the Third Circuit made clear that there are no shortcuts.

According to the plaintiff TPPs, the defendant pharmaceutical manufacturer had marketed the medication at issue as not only treating diabetes but offering cardiovascular benefits too. The plaintiffs claimed that the promotional campaign caused physicians to prescribe the medication at inflated rates, forcing the plaintiffs to reimburse prescriptions they would not otherwise have covered.

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Treat Your AI Like an Opposing Expert: Rule 702 Lessons for Evaluating AI Output

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Attorneys using generative AI can borrow a familiar litigation skill: Evaluate AI-generated output the way they would evaluate an opposing expert witness opinion under Federal Rule of Evidence 702. An expert witness cannot simply “waltz into the courtroom and render opinions” without adequate foundation. Clark v. Takata Corp., 192 F.3d 750, 759 n.5 (7th Cir. 1999). Nor can an expert bridge the gap between data and conclusion with nothing more than ipse dixit — the expert’s own say-so. Gen. Elec. Co. v. Joiner, 522 U.S. 136, 146 (1997).

Rule 702 imposes that discipline directly. It requires expert testimony to be “based on sufficient facts or data,” be “the product of reliable principles and methods,” and reflect “a reliable application of the principles and methods to the facts of the case.” So, when an opposing expert offers an opinion, a litigator’s instinct is not to accept it but to probe its basis and reliability.

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In Case You Missed It: Faegre Drinker on Products — Fall 2025

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Catch up on the latest developments of interest for product manufacturers. Here’s a quarterly compilation of the most popular blog posts on Faegre Drinker on Products.

Register to Do Business, Register to Be Sued? Illinois’ New Jurisdictional Trap for Toxic Tort Litigants

By Elizabeth C. Christen, Jenna Seiler, Natalie Abdou & Bryan D. Pasciak

For companies operating nationwide, rules governing where they can be sued are consequential — especially in high-exposure toxic tort litigation. Illinois’ enactment of SB 328 raises the stakes in these cases even more, conferring general jurisdiction over companies who register or merely transact business in Illinois.

Close, But Not Quite: Eastern District of North Carolina Excludes Experts Whose General Expertise Does Not Enable Specific Opinions Offered

By Eric M. Friedman

Even “[a] supremely qualified expert cannot waltz into the courtroom and render opinions” without passing muster under Federal Rule of Evidence 702. Clark v. Takata Corp. (7th Cir. 1999). A recent case from the Eastern District of North Carolina shows this principle is at play not only when critiquing an expert’s methodology, but also the expert’s expertise.

No Defect, No Negligence: Lessons from Rudzinskas v. Retractable Technologies, Inc.

By Alena Markley

A summary judgment from the Southern District of Georgia shows the critical role of defect evidence (or lack thereof) in negligence claims involving medical devices. In Rudzinskas, allegations that a medical device malfunctioned were not sufficient evidence to survive summary judgment on negligent manufacturing and failure-to-warn claims.

In Case You Missed It: Faegre Drinker on Products — Summer 2025

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Catch up on the latest developments of interest for product manufacturers. Here’s a quarterly compilation of the most popular blog posts on Faegre Drinker on Products.

Tort Reform Is Top of Mind in 2025: Legislative Updates in Georgia, South Carolina, Louisiana and Arkansas

By Elizabeth A. Wurm, Jenna Seiler & Elizabeth C. Christen

Some states that are home to “Judicial Hellhole” venues, often known for producing nuclear verdicts, have rallied for successful tort reform. In the most recent state legislative sessions, Georgia, South Carolina, Louisiana and Arkansas implemented tort reform bills which may serve to neutralize the nuclear verdicts coming out of their courts.

 

Message Received — Delaware Follows Federal Rule of Evidence 702

By Eric M. Friedman & Emma DeLaney Strenski

The Delaware Superior Court took the mass tort world by surprise with its refusal to exclude the plaintiffs’ experts’ causation opinions in the Zantac litigation. But the Delaware Supreme Court granted the defendants’ request for interlocutory appeal and has reversed the Superior Court’s decision and remanded for further proceedings.

 

ChatGPT As Your New Testifying Expert Under Proposed Federal Rule of Evidence 707? Maybe Not.

By Nikolas G. Spilson & Eric M. Friedman

Tools that can reduce the time and cost of litigation have long been in high demand by both clients and counsel. But the tool must be fit for its purpose, and tools that generate evidence or other outputs that will be submitted to the court must pass judicial scrutiny. One of the newer fights concerns the admissibility of machine-generated “expert” opinions.

Close, But Not Quite: Eastern District of North Carolina Excludes Experts Whose General Expertise Does Not Enable Specific Opinions Offered

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Even “[a] supremely qualified expert cannot waltz into the courtroom and render opinions” unless those opinions pass muster under Federal Rule of Evidence 702. Clark v. Takata Corp., 192 F.3d 750, 759 n.5 (7th Cir. 1999). As a recent case from the Eastern District of North Carolina illustrates, this principle is at play not only when critiquing an expert’s methodology, but also the expert’s expertise.

In Williams v. Sig Sauer, Inc., — F. Supp. 3d —, 2025 WL 2643400 (E.D.N.C. Sept. 8, 2025), the plaintiff was an “enforcer” for his motorcycle club who “protect[ed]” and “monitor[ed]” the club members. He alleged that his pistol discharged and injured him while he was adjusting his position on his motorcycle. In support of his product liability claims against the manufacturer of the pistol, he proffered two expert witnesses: a gunsmith and a mechanical engineer. The defendant moved to exclude both experts and filed a motion for summary judgment.

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Nothing Shocking Here – Eleventh Circuit Affirms Defense Win in Electroconvulsive Therapy Case

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When a case involves electroconvulsive therapy (ECT), one might think it originated out of the Twilight Zone. Despite the misrepresentation of such therapies in popular media, modern ECT serves as a valuable option for patients with certain severe mental health conditions who have tried other therapies without success. Although ECT is far safer today than it was when the stigma attached to it was formed, it still carries risks such as confusion, memory loss, and some physical side effects. One need not enter another dimension to envision why a plaintiff might claim damages arising from those risks. Much like Rod Serling’s anthology, the Eleventh Circuit recently closed the door on one such episode.

In Thelen v. Somatics, LLC, — F.4th —, 2025 WL 2749888 (11th Cir.), the plaintiff suffered from depression and mental health issues so severe that he attempted to take his life numerous times in numerous ways. During a two-year span, he received 95 ECT treatments to address his conditions. He was later diagnosed with a neurocognitive disorder that caused severe memory loss.

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