Expert Failing to Explain Source Code Analysis Is Precluded From Testifying

In a decision that will strike a chill into accused patent infringers everywhere, a defense expert has been precluded from testifying at trial about his analysis of source code that was purportedly central to the defendant's non-infringement defense.  Fleming v. Escort Inc., No. 1:CV 09-105 (D. Id. May 23, 2012). The expert's report identified lines of source code that allegedly differed from elements of asserted patent claims, but failed to explain how those lines of source code operated, much less how the source code differed from the patent claims.  Finding that the plaintiff, Fleming, would not have adequate opportunity to analyze the expert's position, the court granted Fleming's Daubert motion.

The defendant, Escort, contended that its "devices lock out false signals by using a process different from that described in Fleming's patents."  However, the expert "never explained how the Escort products lock out false signals."  Instead, the expert's supplemental report incorporated interrogatory answers that simply "identified the lines of source code that perform the function of locking out false signals on Escort devices."  Escort contended that identifying these lines of code was enough to explain how the source code performed the lock-out function.

The court disagreed with Escort.  The expert had merely identified lines in the source code that corresponded to claim elements, without specifying any lines of the source code that performed the lock-out function.  And even if the lines of code identified by the expert did correspond to the lock-out function, the expert had “failed to explain how these lines of code perform that function.”  The expert's opinion therefore failed to meet the test for reliability under Federal Rule of Evidence 702; the expert offered "the classic 'black box,' asserting that the source code makes the products non-infringing because he says so."

Further, the defendant's argument that the plaintiff had waited too long to challenge the expert's report was of no avail, because the report had not met the court's requirements in the first instance.  Likewise, the fact that the plaintiff's expert had analyzed the lines of source code in question did not negate the prejudice it would suffer from the defendant's expert's report.  The plaintiff's expert was forced to make assumptions about his counterpart's ultimate opinion, and the plaintiff had no guarantee that those assumptions would be borne out when the defendant's expert testified.  The plaintiff would be “prejudiced because the first time it will hear how the source code works from [Escort's expert] will be at trial.”

To make Escort's bad day even worse, concurrent with the above decision, the court dismissed state law claims that Escort had brought against Fleming, and struck portions of Escort's invalidity contentions.

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