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February, 2018
Appeals court says testimony of biomechanical expert no, not that biomechanical expert properly admitted in defective ladder case
by Andrew Bergh

Except for those who practice law in a cave, every WSAJ member who regularly represents plaintiffs in car crash cases has undoubtedly gone up against, or at least knows of, a certain biomechanical engineer named Dr. Allan Tencer. For years, the University of Washington Professor of Mechanical Engineering has made a handsome living testifying for the defense about the forces involved in low-speed collisions and whether such forces were sufficient to cause the injuries being claimed by the plaintiff. It is probably safe to say plaintiffs have filed more motions in limine in Washington trial courts to exclude Dr. Tencers testimony than testimony from any other expert.

But fortunately, biomechanical experts are not created equal and in an appropriate case, they can definitely play a significant if not critical role. Ensley v. Tricam Industries, _ Wn. App. _ (2017), provides a good case in point. There, the Court of Appeals (Division One) tackled the issue of whether testimony from the plaintiffs expert in injury biomechanics was properly admitted or whether it never shouldve been considered by the jury because it was too speculative.

On February 12, 2012, Tammy and Raymond Ensley were collaborating on a project in their garage. The task at hand was to staple plastic sheeting to the walls. Tammys job was to hold the sheeting while her husband did the actual stapling. To facilitate her part of the work, Tammy was standing on the second (and middle) step of a stepladder which she had purchased at Costco less than a year earlier. The stepladder was a Rubbermaid TR-3HB model designed by Tricam Industries, Inc. (Tricam), who had also contracted for its manufacture.

The stepladder, which the Ensleys had positioned on the concrete surface of the garage, was neither wobbly nor unstable. Without any prior warning, Tammy suffered what she later described as an instantaneous fall and then face-planted on the floor. Although she initially didnt know what caused her fall, Tammy and her husband soon discovered that one of the two front legs of the stepladder had bent inward at approximately a 45 degree angle.

The Ensleys later filed a product liability action in Skagit County Superior Court against Tricam, Costco Wholesale Corporation, and Newell Rubbermaid, Inc. (The latter defendant presumably distributed the stepladder to Costco and other retail outlets.)

The case went to trial in August 2016. According to the Court of Appeals, Tricam was the only remaining defendant at the end of the case. Its unclear whether this means the Ensleys resolved their claims against the other two defendants prior to trial or at some point during trial before the case went to the jury. What is clear, however, is that Tammy was seriously injured in the stepladder incident because the jury ultimately awarded over $435,000 in damages.

Under the plaintiffs theory of the case, the stepladder was defective both in design and construction. According to the defense, the stepladder met all design standards and thus couldnt have snapped or bent under normal use.

Two design characteristics of the stepladder were especially relevant to the liability issues. First, the front legs of the stepladder were made of one continuous metal tube (think of an upside down U). Second, all three of its steps were riveted to the two front legs. (For those more visually inclined, Division Ones opinion includes an after photograph of the stepladder.)

After what sounds like a veritable battle of the experts, a Skagit County jury eventually sided with the Ensleys. But in its timely appeal, Tricam argued that the testimony from the plaintiffs expert was impermissibly speculative and shouldve been excluded by the trial court.

The expert witness who testified in support of the plaintiffs claims was mechanical engineer Wilson Hayes, a specialist in injury biomechanics. As described by the Ensley court, the methodology employed by Hayes to analyze the accident was pretty straightforward.

Hayes began his analysis by asking one basic question: Did the stepladder break and cause Tammy to fall, or did Tammy fall and cause the stepladder to break? He then came up with four possible scenarios, including three which assumed that Tammy lost her balance and knocked over the stepladder as she fell. Based on Tammys location after the fall, the location of the stepladder after the fall, and the nature of Tammys injuries, Hayes ultimately ruled out all three scenarios. Instead, said the expert, the only plausible scenario was one in which the stepladders leg broke first with Tammy, in reaction to that event, falling forward with her feet caught between the platform and the other leg of the stepladder.

Having determined the most likely scenario, Hayes next analyzed whether the stepladder broke because it was defectively designed and manufactured.

One key observation made by Hayes on the design front? That the leg broke right where a hole had been punched in the metal tube. Punching a hole is necessary, he explained, if you intend to insert a rivet in the leg in order to attach a step. But punching a hole in the metal tube and then not using it is a design flaw at the outset, said the expert, because the hole concentrates the stresses in the tube at the point of insertion.

Hayes further explained how these stresses can be mitigated in the manufacturing process specifically, by grinding down and smoothing the holes punched in the metal tube. This process known as deburring minimizes any differences between holes punched in the front legs of the stepladder. By making the holes identical, said the expert, cracks in a given leg are much less likely. As shown by other evidence, however, Tricam didnt require deburring and in most cases never used it as part of its manufacturing process.

In his closing salvo, Hayes testified that there were feasible and cost-effective design alterations already in use in other products marketed by Tricam which, if also used with TR-3HB stepladders, would have eliminated the defect that caused Tammys fall.

Fighting fire with fire, Tricam countered at trial with its own mechanical engineer (Mark Quan), who rejected out of hand Hayes opinion that the leg of the Ensleys stepladder had bent under Tammys weight while in a stable position with all four feet on the ground. Since this scenario was physically impossible, said the defense expert, the stepladder mustve already tipped before the front leg bent inward.

Quan emphasized two points.

First, he discussed how extensive testing of the same stepladder model had shown not only that it met national design standards but also that it was capable of bearing loads exceeding Tammys weight even where the metal front legs had been intentionally punched with holes that werent smoothed down (i.e., where no burring occurred).

Quan also testified how he had personally tested the unbroken leg of the Ensleys stepladder and found it to have all the qualities it needs to be a safe type 3 stepstool. On cross-examination, however, he admitted that the rivet holes on the unbroken leg would not have been identical to the rivet hole where the other leg broke. His exact words? That rivet holes are never going to be identical.

The jury also heard the deposition testimony of Dennis Simpson, who was a key witness because he had both designed the stepladder in question and overseen its production. (Its unclear from the Court of Appeals opinion whether this evidence was presented by the Ensleys or Tricam.)

Simpson maintained that the manufacturing process for the TR-3HB model was intended to produce identical rivet holes for every leg and every stepladder. (Score one point for Tricam since identical holes mean identical stresses with little or no chance of leg failure.) He acknowledged, however, that Tricam didnt actually require burring; that burring didnt occur in most cases; and that he couldnt say the holes in the Ensleys stepladder were checked during the manufacturing process to ensure they were identical. (Score beaucoup points for the Ensleys, which makes me think they probably presented Simpsons deposition testimony in their own case in chief.)

Against this background, the trial court gave the pattern jury instructions on design and construction defects. (See WPI 110.01 and 110.02). Although jurors ruled against the Ensleys on their design defect theory, they returned a verdict finding that the stepladder was not reasonably safe in construction at the time the product left [Tricams] control. Thereafter, Tricam sought a new trial on the ground that Hayes testimony was too speculative to support a finding of a construction defect.

As noted by Division One, trial courts have broad discretion in determining the admissibility of expert testimony under ER 702. The general principles include the following:

Once the trial court is satisfied with the experts qualifications, the test for admissibility is whether the testimony will assist the trier of fact to understand the evidence or to determine a fact in issue.

The trial court must also consider whether the issue is of such a nature that the expert can express a reasonable probability rather than mere speculation or conjecture.

When ruling on somewhat speculative testimony, the trial court must keep in mind the risk that the jury may be overly impressed with a witness who possesses the aura of an expert.

The Court of Appeals next discussed the elements of the plaintiffs construction defect claim. Under the pattern instruction given to the jury, there are two tests for proving this type of claim. First, the Ensleys could show the stepladder had deviated in some material way from its intended design. And second, they could show the stepladder was unsafe beyond what an ordinary user would reasonably expect.

At the end of the day, Division One concluded that the Ensleys had satisfied both tests.

First of all, given Hayes testimony about the irregularities in the rivet holes in combination with Simpsons testimony that Tricam intended them to be identical and Quans testimony that rivet holes are never identical the jury could find the stepladder had deviated from its intended design, the Ensley court concluded. The second test was also met, said Division One, since an ordinary user of a stepladder wouldnt expect a leg to break while engaging in normal use of the product.

Refusing to throw in the towel, Tricam cited three federal cases where the trial court excluded expert testimony that the stepladders from which the plaintiffs fell were defective. The Court of Appeals readily distinguished each of them, however, concluding its opinion with the following:

Hayes testimony was not speculative, conclusory, or uncertain. His opinions were supported by the Ensleys testimony about the circumstances of the accident and were stated to a reasonable degree of scientific certainty. Hayes employed a scientifically accepted methodology (accident reconstruction) and engaged in demonstrably thorough analysis. He gave fact-based opinion testimony helpful in understanding how an individual stepladder could fall during normal use even it its design met industry standards. The court did not err in admitting his testimony and allowing the jury to consider the construction defect claim.

When reading the opinion in Ensley v. Tricam Industries, one gets the distinct impression that Tricam never gives any quarter and aggressively defends any product liability claim involving one of its stepladders. This is all the more reason to give credit to the Ensleys and their attorney for winning what was certainly a hard-fought battle. A huge assist was surely earned by Wilson Hayes, however, which goes to show that a biomechanical expert in an appropriate case can play an invaluable role.

Andrew Bergh, WSTLA EAGLE member, former prosecutor and insurance defense attorney, now limits his practice to plaintiff's personal injury cases, including professional liability and insurance bad faith.