Expert Witness Profiler

Category: Polymers Expert Witness

  • Polymers Expert Not Allowed to Opine on Content of Internal Documents

    Polymers Expert Not Allowed to Opine on Content of Internal Documents

    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.

    Want to know more about the challenges Jimmy Mays has faced? Get the full details with our Challenge Study report.

    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
  • Polymers Expert Allowed to Opine on PFOS Sources

    Polymers Expert Allowed to Opine on PFOS Sources

    This case arises out of the contamination of surface waters and drinking water in Chattooga County, Georgia, with per- and polyfluoroalkyl substances known as “PFAS.”

    In essence, Plaintiff Earl Parris, Jr., alleged that the Defendants have contaminated his water with PFAS. Parris is a resident of Summerville, Georgia, who receives running, potable water to his home from the Summerville Public Works and Utilities Department.

    The City of Summerville—which has intervened in this case—used Raccoon Creek, a tributary of the Chattooga River, as the main source of its municipal water supply. Parris alleged that Raccoon Creek and—consequently, his household water—have been contaminated with PFAS by the Defendants. At present, Parris and Summerville jointly moved to exclude the opinion testimony of Defendant 3M’s expert, Maureen Reitman.

    Polymers Expert Witness

    Maureen Theresa Fahey Reitman, Sc.D. has been practicing in the field of polymer science and engineering for more than 30 years.

    She has a Doctor of Science in Materials Science and Engineering, with a thesis in the field of polymers, from MIT. She is also a licensed Professional Engineer in the state of Maryland and a Fellow of the Society of Plastics Engineers.

    Get the full story on challenges to Maureen Reitman’s expert opinions and testimony with an in-depth Challenge Study.

    Discussion by the Court

    Relevancy and Likelihood of Confusion

    Plaintiffs asserted that Reitman failed to identify any perfluorooctane sulfonate (PFOS)-containing products at the Mount Vernon Mill or the Trion Water Pollution Control Plant (“Trion Plant”) other than 3M’s product.

    The Court agreed with 3M that Reitman’s opinions as to other possible sources of PFAS and PFOS in the Raccoon Creek watershed are relevant to the issue of causation. Although it is 3M’s burden to establish the relevance and reliability of their expert’s opinions, it is ultimately the Plaintiffs’ burden at trial to prove the causal connection between their alleged injuries and the Defendants’ alleged actions.

    Here, 3M sought to introduce evidence undermining the Plaintiffs’ causation evidence by showing that there were other possible causes of the Plaintiffs’ injuries. Thus, the Plaintiffs’ argument that Reitman cannot determine “to what extent, if any, a participant in the global supply and use network for PFAS released a particular substance into the environment at issue” entirely missed the mark—the fact that Reitman is testifying she cannot make this determination is the whole point of introducing her testimony.

    3M intended to rely on this testimony to argue that the Plaintiffs cannot prove its product is the cause of the alleged PFAS contamination in the Raccoon Creek watershed.

    The Plaintiffs also sought to exclude Reitman’s opinions under Federal Rule of Evidence 403, arguing that her testimony about PFOS sources manufactured abroad will confuse the jury because such sources are irrelevant to their claims. Because Reitman’s testimony is relevant and will be helpful for the jury, the extraordinary remedy of exclusion under Rule 403 is unwarranted here.

    Reliability

    Plaintiffs asserted that Reitman admitted she does not have any data indicating PFOS sources besides 3M’s product are present in the Raccoon Creek watershed, yet she seeks to testify that other possible sources exist.

    However, Reitman’s report explains the reasons why the identification of PFOS and PFAS “in an environmental sample is not sufficient to identify the original source of production.” Further, she explains why this is true regardless of the characteristics in a sample associated with electrochemical fluorination (ECF), a process that 3M is known to have utilized in processing PFOS.

    And she provided testimony critical to 3M’s causation defense that the Plaintiffs have not provided an appropriate scientific basis for excluding other possible suppliers of the specific PFAS at issue due to the potential contributions of products associated with global supply chains.

    The fact that Reitman’s opinions may undermine the causation evidence the Plaintiffs intend to present does not make them unreliable; instead, the Plaintiffs’ concern goes to the weight and credibility of the evidence. The Plaintiffs will have the opportunity to cross-examine Reitman at trial, where their concerns will be more appropriately addressed.

    Held

    The Court denied the Plaintiff and Intervenor-Plaintiff’s joint motion to exclude the opinions of Maureen Reitman.

    Key Takeaway

    In the Court’s view, the Plaintiffs did not truly challenge the reliability of Reitman’s opinions, but instead challenged the content of her opinions. But the Court’s inquiry at this stage “must be solely on principles and methodology, not on the conclusions that they generate.”

    Case Details:

    Case Caption: Parris V. 3M Company
    Docket Number: 4:21cv40
    Court Name: United States District Court, Georgia Northern
    Order Date: March 09, 2026