It’s essential to understand your jurisdiction’s standards for expert qualification—typically Rule of Evidence 702 and admissible scientific testimony. If you’re an expert, the opposing party may challenge your testimony or qualifications. If you’re an attorney, you must establish that the expert is qualified, and their testimony is reliable and accurate.

Therefore, it’s important to understand how courts handle experts and utilize the Daubert analysis. Take a look at five situations in which a court excluded an expert witness’s testimony.

1) Testifying to the Wrong Specialty

Pay close attention to the expert’s specialty and whether their testimony might reach outside the bounds of that specialty.

The case Carter v. United States centered around a child’s treatment for a severe asthma attack in the emergency room. The plaintiff retained a pulmonary medicine expert to testify regarding the standard of care in the emergency room. The plaintiff offered his testimony as an emergency medicine expert, even though he didn’t practice as an emergency room physician.

Nonetheless, Louisiana courts deemed emergency medicine its own specialty. Because of this, the defendant argued the expert’s opinion was beyond the scope of his expertise. The court agreed. As a result, the court allowed the expert to testify regarding the diagnosis and treatment of asthma. However, the expert could not opine on the standard of care in the emergency room.

2) Inconsistent Expert Witness Testimony

When retaining an expert to testify regarding scientific or medical topics, review the expert’s previous opinions in similar cases. Inconsistencies in an expert’s opinions, which lack a scientific basis, call into question their reliability.

In Jagoe v. Sec’y of the HHS, the plaintiffs retained a board-certified internal medicine physician to testify regarding immunology. Specifically, the issue was causation and the timing of the child’s illness in relation to when they received the vaccination.

The court addressed several issues, including the expert’s mischaracterization and disregard of certain evidence. However, the most significant concern was the expert’s inconsistent testimony between the current case and another similar case. Previously, the expert had testified that it takes at least 96 hours for signs of the disease to show. However, while in the matter at hand, she testified 36 hours is sufficient.

The expert withdrew from the case, and the petitioner failed to reconcile the conflicting opinions. As a result, the court found the expert witness’s testimony wholly unreliable and gave no weight to her opinion.

3) Lack of Research and Acceptance

Smith v. Braswell was a birth injury lawsuit in Georgia. The plaintiff retained an obstetrician/gynecologist (OB/GYN) with a maternal-fetal medicine subspecialty. The expert opined about the mechanics that caused the birth injury. However, he hadn’t practiced for many years and primarily conducted research and lectured. The OB/GYN expert believed the infant’s injury was due to a mechanism he called “cranial compression ischemic encephalopathy” (CCIE).

Ultimately, the court excluded the expert witness testimony. The expert did not reliably test his theory regarding CCIE. Additionally, his theory was not published in any peer-reviewed publications nor was it generally accepted by the scientific community.

4) Lack of Scientific Methodology

Meemic Ins. Co. v. Hewlett-Packard Co. was an insurance subrogation dispute arising from a fire. The plaintiff retained an electrical engineering expert to inspect a printer’s AC power adapter, a possible source of the fire. The expert claimed the power adapter caused the fire. This claim was based on a visual examination of the device and its location near where the fire originated.

In the end, the court excluded the witness’s testimony because it was not based on reliable scientific principles and methods. The expert offered no generally accepted methodology for how he reached his conclusion. Instead, his opinion was based only on his real-world experience.

5) Lack of Reliability

In Flores v. Allstate Tex. Lloyd’s Co., homeowners and an insurance company disputed whether mold made the plaintiff’s home uninhabitable and caused them harm. They retained a board-certified family medicine physician.

The court found the expert witness’s testimony lacked reliability. The expert testified regarding a hypothetical situation. However, he did not perform testing. In addition, he couldn’t point to any testing that demonstrated a connection between the type of mold in the plaintiff’s house and the plaintiff’s alleged health problems. He hadn’t conducted any studies regarding the type of mold or based his testimony on peer-reviewed research. The court found the testimony wasn’t generally accepted by the scientific community, and the potential for error was “virtually limitless.”

Be Mindful of the Daubert Standard

Any time an expert witness is called, it’s important that both the expert and the hiring attorney understand the jurisdiction’s standard for experts. Opposing counsel may challenge the expert’s qualifications or testimony. If this happens, it’s the attorney’s responsibility to prove that the expert is qualified and offers reliable and relevant information.

All federal and most state trial courts follow the Daubert standard, set out in Daubert v. Merrell Dow Pharmaceuticals Inc. A trial judge determines whether an expert witness’s scientific testimony is valid and reliable based on several factors:

  •       Whether the theory or technique in question can be and has been tested
  •       Whether it has been subjected to peer review and publication
  •       Its known or potential error rate
  •       The existence and maintenance of standards controlling its operation
  •       Whether it has attracted widespread acceptance within a relevant scientific community

Few states follow a modified Daubert standard, and others retain the Frye standard set out in Frye v. United States. Whatever the jurisdiction’s standard, prepare to overcome a challenge in court.

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