In Guangzhou Yucheng Trading Co., Ltd. v. Dbest Products, Inc., a patent infringement action in which the plaintiff, Guangzhou Yucheng Trading Co., Ltd.’s (“GYT”), sought a declaratory judgment that its “stair climber” portable shopping cart product does not infringe U.S. Patent No. 9,233,700 (“the ’700 Patent”), the court recently ruled on three motions relating to GYT’s expert witness, David G. Smith (“Smith”). In two of the motions, the defendant, Dbest Products, Inc. (“Dbest”), moved to exclude certain infringement and invalidity opinions offered by Smith, and in the third motion Dbest moved to exclude Smith’s rebuttal expert report. The court granted all three motions. With respect to infringement, Dbest argued that some of Smith’s opinions should be excluded because the opinions were based on claim construction arguments that were inconsistent with the court’s Claim Construction Order. The court agreed with Dbest and excluded Mr. Smith’s opinions as to four claim terms, because his opinions provided “narrowing constructions” that were inconsistent with the court’s construction of those terms. Id. at *10 (“An expert opinion that is contrary to or ignores a court’s claim construction is irrelevant and unhelpful to the trier of fact, and as such, is inadmissible and must be excluded.” (citations omitted)). The court did note that “experts ‘may introduce evidence as to the plain...