Deconstructing patent claim construction hearings

Craig Metcalf

In 1996, the United States Supreme Court decided the case of Markman, et al. v. Westview Instruments, Inc., et al. The case held that the question of interpretation of patent claim language is an issue for the judge, not the jury. As the Supreme Court noted, patent lawsuits charge infringement of patent claims. Every patent infringement claim is based on the plaintiff’s assertion the defendant is making, using or selling a product that practices every element of a patent claim. Thus, prevailing in a patent infringement action requires that the court understand the asserted patent claims the same way the plaintiff does. Courts come to this understanding through claim construction which takes place in the Markman hearing.

Claim construction begins with the language of the claim. The claim terms are presumed to mean what they say. Thus, it is common for the courts to indicate that claim terms are given their ordinary and customary meanings. Courts should look to the words themselves to define the scope of the patented invention.

Claims should be construed in light of the context in which claim terms are used by a person of ordinary skill in the relevant art. This should include knowledge of the accused product or process in order to provide a meaningful context for the claim construction.

In order to understand the meaning of the claim terms, courts should rely first on the “intrinsic” evidence of the record of the patent application. This evidence includes the claims themselves, the patent specification, the drawings and the Patent Office prosecution history. That is, evidence within the direct prosecution file of the patent.

If the intrinsic record is ambiguous and requires further explanation, the courts can allow the introduction of “extrinsic” evidence. This is evidence beyond the scope of the patent itself and its prosecution history. Extrinsic evidence commonly includes dictionary definitions and learned treaties. It may also include expert and inventor testimony. As mentioned above, however, the focus of claim interpretation should still be the claim terms themselves.

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