Courts Must Justify Admission of Expert Testimony, US Appellate Court

A district court must record its Daubert inquiry and explain its basis for admitting expert testimony, the US Court of Appeals Fifth Circuit has ruled, as have three other circuit courts in similar cases. The fact that the expert witness was never formally designated as such was irrelevant; the content of testimony determines whether the Federal Rules of Evidence apply (specifically, Rule 702), the court said.

In Carlson v. Bioremedi Therapeutic Sys., U.S. Court of Appeals, 5th Cir., 2016, David Carlson was treated by a chiropractor with a product called the "ProNeuroLight" for diabetic peripheral neuropathy, a condition of numbness and general loss of feeling in the bodily extremities, especially the feet. After the treatment, Carlson found ulcers on his feet, which resulted in a bone infection, requiring over a year of hospitalization and ultimately the amputation of one leg below the knee, and a heel amputation of the other foot.

Carlson and his wife brought a product liability suit against the manufacturer and the distributor of the ProNeuroLight, Bioremedi Therapeutic Systems Inc. and Light Emitting Designs Inc. Carlson's treating diabetic podiatrist and podiatry expert witness, Dr. Scott Margolis, testified that Carlson's ulcers were caused by the infrared therapy provided by the ProNeuroLight. Carlson's biomedical engineering expert witness, Dr. Yadin David, testified that there were reports of burns associated with infrared therapy devices like the ProNeuroLight, and that such therapies were "worrisome" as those with peripheral neuropathy were at a greater risk of burns since they had lost protective nerve sensation.

The defendants brought only one expert witness, Dr. Lance Durrett, a practicing chiropracter with approximately 14 years' experience using devices like the ProNeuroLight. Before trial, Carlson moved to exclude Durrett's medical testimony. The district court denied the motion without explanation or comment.

At trial, Durrett opined at first that he could not conclude whether or not the ProNeuroLight caused the burn injuries or not, but later testified that the device was incapable of causing the injuries because he said it was designed not to raise surface temperatures more than two degrees.

While the defendants never designated Durrett as an expert witness, the appellate court noted that that the defendants refered to his "expert opinions", and regardless, Durret was opinining on medical causation, which would fall under Rule 702 of the Federal Rules of Evidence as such testimony must rest on "specialized knowledge."

Under Daubert, the gatekeeping function "… imposes a special obligation upon a trial judge …" to ensure all scientific testimony is relevant and reliable, the appellate court noted. Whether or not Durrett was qualified to give expert medical causation testimony was not relevant to its decision, the appellate court said (although it implied that it did not believe Durrett was qualified).

Even though a district court "… is not always required to hold a formal Daubert hearing", the court is required to conduct a Daubert inquiry or to at least make a Daubert determination on the record, both of which the district court in this case failed to do. At a minimum, a district court must explain its basis for admitting expert testimony, the appellate court found. Instead, the district court in this case simply informed the jury that it found the testimony admissible.

That act disregarded the trial court's gatekeeping function, the appellate court said, finding that the district court abused its discretion, and that the admission of Durrett's testimony was not harmless, therefore reversing and remanding the case.