In December 2020, Diana Dyer “was surgically implanted with an Aris™ Trans-Obturator Sling System (hereinafter the ‘Aris’), a pelvic mesh product and medical device designed, manufactured, and marketed by Defendants,” which “was intended to treat pelvic organ prolapse and stress urinary incontinence.”
Dyer claimed that she “has suffered, and continues to suffer, debilitating injuries” “as a result of being surgically implanted with Defendants’ unreasonably dangerous defective pelvic mesh device.”
Dyer retained as an expert Dr. Jimmy W. Mays, a “Professor Emeritus in the Department of Chemistry at the University of Tennessee.” Mays opined that the Aris is not suitable to serve as a permanent implant.
Coloplast sought to exclude the opinions of Mays.
Polymers Expert Witness
Jimmy Wayne Mays has a Ph.D. in polymer science and has worked extensively in the area of polymeric biomaterials.
Discussion by the Court
A. Oxidative Degradation Opinions
Mays opined that polypropylene mesh undergoes oxidative degradation in the human body, which causes the mechanical properties of the mesh to break down.
1. Relevance and Helpfulness to Jury
Coloplast argued that Mays’ opinions are “irrelevant and unhelpful because there is no evidence that [Dyer’s] Aris implant degraded or that any purported degradation caused her alleged injuries.”
Dyer asserted that there is evidence in the record that the Aris’ mesh “was defective and that safer alternatives would have mitigated the complications of the ‘excessive and unpredictable’ foreign body response experienced by Dyer.” The Court agreed with Dyer and found Mays’ testimony relevant and helpful to the jury.
2. Reliability
Coloplast argued that Mays lacked a reliable basis to opine that Coloplast’s polypropylene mesh implants degrade in the body. Mays cited many scientific studies to support his opinion that the addition of antioxidants may delay but cannot prevent the oxidative degradation of polypropylene mesh.
Coloplast has not demonstrated that there is too great an analytical gap between the studies Mays cited and his opinion regarding the Aris’ polypropylene mesh.
B. Clinical Complications
Coloplast argued that Mays “lacks the necessary qualifications to offer opinions concerning potential clinical complications resulting from the purported degradation because he is not a medical doctor and has no medical training.” In response, Dyer represented that Mays will not opine on the medical complications associated with polypropylene mesh.
C. Reduction of Mechanical Properties
Mays stated that the degradation of polypropylene in vivo is “accompanied by a decrease in mechanical properties (embrittlement, loss of mass, decreased melting temperature, reduced compliance) of the polypropylene.”
Coloplast noted that Mays admittedly “is not qualified to quantify the degree of stiffness purportedly resulting from oxidative degradation in vivo or the degree of stiffness necessary to produce clinical symptoms in a patient, and he is unaware of any scientific literature attempting to do so.”
Dyer represented that Mays will not offer opinions regarding clinical complications associated with polypropylene mesh. However, Mays, an expert in polymer science and biomaterials, cited multiple scientific articles in support of his opinions regarding the reduction of the mesh’s mechanical properties. The Court found that Mays’ opinions on this issue are reliable.
D. Toxicology Opinions
Coloplast argued that Mays “is unqualified to opine on the alleged toxicity or irritability of polypropylene resin or antioxidants.”
In response, Dyer represented that “Mays will not opine as to the toxicity of polypropylene resin or antioxidants.” Accordingly, the issues of whether Mays is qualified to offer opinions on toxicity and whether his opinions are reliable and helpful to the jury are moot.
However, Dyer did not address the issue of whether Mays is qualified to testify as to the alleged irritability of polypropylene resin or antioxidants. Accordingly, the Court treats this portion of the motion as unopposed.
E. Safer Alternatives
Coloplast argued that Mays “lacks both the qualifications and the necessary data to opine that polyethylene, poly(vinylidene fluoride) (PVDF), and P4HB meshes” are safer alternatives to polypropylene mesh.
In response, Dyer represented that Mays will not opine as to whether PVDF or P4HB is “safer” than polypropylene mesh.
Accordingly, Coloplast’s argument regarding PVDF and P4HB mesh is moot. As Dyer did not address Coloplast’s contention that Mays is not qualified to opine that polyethylene mesh is a safer alternative to polypropylene mesh, the Court treated this portion of the motion as unopposed.
The Court granted the motion to the extent of excluding Mays’ opinion that polyethylene mesh is a safer alternative to polypropylene mesh.
F. Legal Conclusions, Contents of Internal Documents, and Opinions on Coloplast’s State of Mind and Conduct
Finally, Coloplast asked the Court to exclude Mays’ legal conclusions, summaries of internal documents, and opinions on Coloplast’s state of mind or corporate conduct.
The Court denied the motion as moot to the extent Coloplast sought to preclude Mays from offering legal conclusions or opining on Coloplast’s state of mind or corporate conduct. Mays is not precluded from offering testimony that uses terms that do not have a separate, distinct, and specialized meaning in the law.
The Court granted the motion to the extent Coloplast asked the Court to “preclude Mays from testifying as to the content of Coloplast’s internal documents.” However, Mays “may testify as to a review of internal corporate documents solely for the purpose of explaining the basis for his or her opinions — assuming the opinions are otherwise admissible.”
Held
The Court granted in part and denied in part Defendant Coloplast Corp.’s motion to exclude the testimony of Jimmy Mays, Ph.D.
Key Takeaway
Simply parroting documents or other testimony does nothing to assist the trier of fact. Mays also may not summarize Coloplast’s internal documents.
Please refer to the blog previously published about this case:
Gynecology Expert Not Allowed to Opine on Corporate Intent
Case Details:
| Case Caption: | Dyer V. Coloplast Corp. |
| Docket Number: | 8:24cv2867 |
| Court Name: | United States District Court, Florida Middle |
| Order Date: | July 02, 2026 |
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