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After Claim Construction, District Court Allows Opposing Experts to Testify to Different Definitions of “Using” At Trial and the Jury Can Decide Who Had the Better Interpretation

The parties filed opposing motions against each side’s expert witness over a dispute between the parties as to what the word “use” means. In its Markman order, the district court had construed the term “Internet Protocol network” (“an Internet Protocol network,” “network utilizing at least one Internet Protocol,” and “a network utilizing at least one Internet Protocol”) to mean “an untrusted network using any protocol of the Internet Protocol Suite including at least one of IP, TCP/IP, UDP/IP, HTTP, and HTTP/IP. . . .”

The plaintiff, Prism, filed a motion to exclude the opinions of Dr. Mercer, arguing that Dr. Mercer impermissibly construed “using” to mean “routing.” The defendant, Sprint, moved to strike or exclude the “new” opinion of Mr. Minor, alleging that Mr. Minor impermissibly construed “using” to mean “carrying.” The district court explained that “[i]n the current motion to exclude conflicting expert testimony, the issue before the Court is whether these constructions are consistent with the Court’s construction of ‘Internet Protocol Network.'”
After reciting the standards for challenging expert testimony, the district court concluded that “[t]he parties each hold the burden for substantiating the admissibility of their experts’ opinions. Though each side argues vigorously that their expert’s opinion is the sole interpretation of the word “using,” the Court does not agree. Both interpretations are reasonable on their face.”

The district court then stated that the parties could cross-examine the experts and the jury would determine the issue. “When the conflicting opinions are offered, opposing counsel can cross-examine that expert and let the jury decide who holds the better interpretation. The Court further finds that the purportedly new opinion is not new because it falls within the scope of Mr. Minor’s expert report.”

Prism Technologies, LLC v. Sprint Spectrum L.P., Case No. 8:12CV123 (D. Neb. June 9, 2015)

The authors of are patent trial lawyers at Jeffer Mangels Butler & Mitchell LLP. For more information about this case, contact Stan Gibson at 310.201.3548 or