Biomechanics Expert Witness Testimony Not Allowed

Plaintiff sued defendant related to a shooting involving a policeman and two individuals.  The defendants hired a Biomechanics Expert Witness to provide testimony.  The plaintiff filed a motion to exclude this expert witness from testifying.  The court granted the motion to exclude.

Facts:  This case (Thompson et al v. City of Olympia et al – United States District Court – Western District of Washington – August 16th, 2019) involves a a shooting that occurred in Olympia in May 2015 by the side of the road.  The defendant, a police officer, pulled over the plaintiffs on suspicion or shoplifting and assault.  The defendant testified that he shot the the plaintiffs after they attacked him.  The plaintiffs maintain that they ran away and were pursued by the defendant.  The defendants have hired Biomechanics Expert Witness Louis Cheng to provide testimony.  The plaintiff has filed a motion to exclude this expert witness from testifying.

Discussion:  The court notes that much of Cheng’s opinions come from a reenactment of the incident by the defendant, which Cheng captured and digitally rendered using his 3-D camera.

The court first opines that Cheng’s opinions related to the defendant’s reenactment fail under the Daubert standard.  The court opines that to the extent that Cheng opines about the reenactment as if it were accurate information, these opinions are not based on reliable methodology.  The court opines that Cheng seems to have relied only on the defendant’s memories when creating his graphics.

The court notes that Cheng states that he recorded the movements and turned the “point cloud data” into “human figure representations”, which he states is generally accepted in the biomechanical community to predict human body movement.  The court opines, however, that these statements do not explain how Cheng’s methods allowed him to confirm the objective accuracy of his images.

The court notes that Cheng stated in his deposition that he tried his best not to influence the defendant when he staged the reenactment with stand-ins.  The court also opines that the defendants cannot state that Cheng’s graphics are both a “hands off” reenactment of the defendant’s memory and an accurate depiction which was assembled scientifically from the evidence.

The court opines that Cheng came to broad conclusions that favor the defendants without presenting objective, verifiable evidence of underlying scientific research or principles.

The court also opines that Cheng should not be allowed to opine that the defendant’s description of events is most likely the truth without scientific valid evidence.

The defendants argue that the plaintiffs issues with Cheng’s opinion go to the weight of the evidence and thus should be addressed during cross-examination.  The court disagrees, stating that Cheng’s scientific methodology seems to have begun and ended with his 3-D camera.

Conclusion:  The motion to exclude the expert witness testimony of Louis Cheng is granted.