An expert witness is someone who applies a reliable methodology to a given set of facts to help a jury understand facts that might be beyond the common understanding of lay jurors. If there is no methodology, there is no opinion. Similarly, if the expert’s opinions do not help a jury understand a complicated fact, they are inadmissible.
Both these topics arose in De Blanc v. Aloha Airport Express, LLC. The plaintiff was a passenger in a shuttle van. When the van reached its destination, the driver placed a step stool next to the van to assist passengers in stepping down to the pavement. Plaintiff fell as she used the step stool to exit the van. There were competing theories as to why she fell when using the step stool.
Plaintiff disclosed Lane Swainston as an expert witness to testify concerning liability. He concluded the step stool’s “locking mechanism is not reliable and is subject to operator error or failure of the mechanism to latch shut.” He then concluded it “is not stable under loading that is not deliberately centered on the platform. If the platform is not properly placed by the driver, it is especially unsafe when used to exit a vehicle.” He ultimately concluded Plaintiff’s fall was caused by the step stool.
The court excluded Swainston. As to his first conclusion, it was “not the product of reliable principles and methods.” Although his report stated he observed the problems he described, he “does not explain how he came to his conclusion that the locking mechanism is not reliable and is subject to operator error or failure. Swainston does not identify any principles or methods to support his conclusions, much less reliable ones.” The court also concluded this opinion would not assist a jury. “It seems the jury could observe the stool and reach its own conclusion, rendering expert opinion unnecessary.”
The second conclusion was also inadmissible. “This conclusion does not assist the jury. The jury can understand that a step stool may be unstable if the user does not step in the center of it. And the jury is capable of determining whether Aloha acted reasonably in this context.”
The ruling is notable for me in at least two ways. As to the methodology problem, this is a recurring issue that I see with expert witnesses. For whatever reason, they give a summary opinion that does not “show your work.” That then leads to rulings like this. When preparing an expert disclosure or evaluating one from an opponent, start at the beginning: is there a reliable methodology that is being applied?
My other note from this order is my own personal feeling that lawyers hire liability experts too often. There are cases that simply require them, but the vast majority of tort cases just don’t. When hired in cases like this one it can lead to thin opinions that do not assist the jury to understand a disputed fact. This in turn increases the risk of exclusion or a jury zoning out during the expert’s testimony because it serves no substantive purpose.
 416 F. Supp. 3d 1056 (D. Nev. 2019). Full disclosure, I represented the defendant.
 Id. at 1063.