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Motion to Strike Expert Testimony Denied Even Though Expert Had Never Used Product and Examined Only Selected Pieces of Source Code

In this patent infringement action, the defendant moved to exclude portions of the plaintiff’s (Dr. Bambos’) expert testimony. Defendant argued that Dr. Bambos lacks familiarity with the infringing products, relied too heavily on someone else to provide him with relevant segments of source code to review, and used the district court’s claim construction to determine how the products work.

In analyzing the motion, the district court noted that “Dr. Bambos never used the allegedly infringing products, but his expert opinion was based on ‘thousands of pages of technical manuals, source code, and depositions transcripts.’ (D.I. 221 at p.1) (See D.I. 221-4 at 3-6; D.I. 221-3 at 2-5). Rule 702 requires that expert testimony be based on “sufficient facts or data.” Dr. Bambos need not use the product if, as here, he has familiarized himself with it in other ways. Reviewing source code and other materials can be sufficient.”

The district court thus rejected that the expert had to personally use the product. “Whether Dr. Bambos should have based his expert opinion on personal use with the product, rather than source code and other materials, is fodder for cross-examination, not a Daubert issue for this Court.”

The district court also rejected excluding the expert because he relied too heavily on his expert report during his deposition. ” Defendant contends that, because Dr. Bambos relied too heavily on his written report during the deposition, he is unfamiliar with the products and too unreliable to appear before a jury. (D.I. 172 at pp.5-6). Defendant states that Dr. Bambos spent over 25 minutes reading the report to find the answer to a particular question about the infringing products, continuing reading into his lunch break. (D.I. 172 at p.5). The deposition record, however, reveals a more complicated exchange, where the witness was repeatedly told by both lawyers that he could take his time, even though he spent considerable time reviewing the report while answering questions. (See D.I. 174 at 115-25). Defendant also points out other examples of relying on the report to answer questions about the product. (D.I. 172 at pp.5-6). In other words, Defendant says Dr. Bambos will be a poor witness, at least unless he is better prepared for trial than he was for deposition. Whether Dr. Bambos relied too heavily on his report in his deposition does not, in my opinion, raise a Daubert issue.”

Finally, the district court declined to exclude the expert because he had only review part of the source code. “Defendant argues that because Dr. Bambos reviewed selected pieces of source code provided by someone else, rather than the complete source code of the products by himself, his testimony should be excluded. (D.I. 172 at pp.6-7). Even if Dr. Bambos did not know the qualifications of the individual who selected the pieces of source code, or whether there might be other relevant segments of the source code, he was able to determine whether the sections of code related to the elements relevant to infringement. (D.I. 221 at p.6) (See D.I. 221-4 at 12¬13). Therefore, his expert opinion is based on sufficient facts and reliable methods. Whether Dr. Bambos should have consulted the complete source code, and might have missed something that would change his opinion, is an issue for cross-examination and, possibly, contradictory expert testimony by Defendant’s expert. Ultimately, the jury will decide Dr. Bambos’ credibility.

IPLearn, LLC v. Blackboard Inc., Case No. 11-876 (RGA) (D. Del. Sept. 6, 2014)

The authors of are patent trial lawyers at Jeffer Mangels Butler & Mitchell LLP. We represent inventors, patent owners and technology companies in patent licensing and litigation. Whether pursuing patent violations or defending infringement claims, we are aggressive and effective advocates for our clients. For more information contact Stan Gibson at 310.201.3548 or