Massachusetts Court Limits Expert Testimony in Covidien Mesh MDL
A Massachusetts court permitted some causation testimony but narrowed expert opinions in Covidien hernia mesh MDL.
Why it matters: Litigators handling product liability and mass tort cases face renewed guidance on expert testimony standards, directly impacting trial strategies in medical device litigation nationwide. The ruling clarifies how courts will scrutinize the reliability and factual basis of expert opinions under Federal Rule of Evidence 702.
- On April 27, 2026, the Massachusetts District Court issued key evidentiary rulings in Covidien’s hernia mesh multidistrict litigation (MDL No. 3029).
- Dr. Stephen Ferzoco may testify on general and specific causation and warnings, but not on safer alternative designs.
- Covidien's expert Dr. Corey Deeken can opine that the Symbotex mesh is safe; plaintiff’s challenges to his testimony were denied.
- The court excluded Dr. Laura Plunkett’s testimony on postmarket surveillance but allowed her other opinions.
- Approximately 2,387 active lawsuits remain in the Covidien hernia mesh MDL as of April 2026.
The U.S. District Court for the District of Massachusetts issued a critical ruling on April 27, 2026, clarifying how expert testimony is to be evaluated in the ongoing multidistrict litigation concerning Covidien’s hernia mesh products (CaseMine).
- The court permitted Dr. Stephen Ferzoco’s testimony on causation issues and Covidien’s product warnings, but found his opinions on safer alternative designs lacked sufficient factual backing and excluded them (memorandum & order).
- Dr. Corey Deeken, serving as an expert for Covidien, is allowed to testify that the Symbotex mesh is safe, rebuffing plaintiff efforts to exclude his input (federal court filings).
- The court also granted part of Covidien’s request to strike Dr. Laura Plunkett’s review of postmarket surveillance, citing Rule 702 limitations, but her other opinions are admitted (filings).
Judge Patti B. Saris emphasized that “A district court is well-justified in striking opinion testimony that depends upon ‘the ipse dixit of the expert’ or that evinces significant ‘analytical gap[s] between the data and the opinion proffered.’”
This decision arrives as roughly 2,387 active lawsuits continue in MDL No. 3029 (Drugwatch), offering critical guidance on expert admissibility for ongoing and future product liability litigations involving medical devices.
By the numbers:
- 2,387 — Approximate number of active lawsuits in the Covidien hernia mesh MDL as of April 2026
- April 27, 2026 — Date of the court’s evidentiary rulings in the MDL