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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In view of the realities of litigation, including the docket of the judge, parties and counsel should use discretion in deciding which terms to have the judge construe in a Markman hearing. The focus should be on claim terms that may be determinative of the question of infringement. Also, the parties may wish to focus on terms that may not have a precise definition in the patent or common usage, but which are important in determining the scope of the claim. Examples from recent cases include the terms “substantially pure” in a claim for a pharmaceutical composition and “spaced relationship” in a claim for an electromechanical device. These terms were not specifically defined in the patent or in common usage, but the courts were able to construe their meanings in view of evidence of the type discussed above.

One important question is when a Markman hearing should be held. If a Markman hearing is held early in the litigation, this gives the parities a roadmap for the ongoing litigation and may even result in settlement of the case. The problem with an early Markman hearing is discovery may not have progressed sufficiently to allow for a complete and accurate claim interpretation.

Another option is to conduct the Markman hearing toward the end of discovery, but sufficiently in advance of trial to allow for the results of the Markman hearing to be used to prepare for trial or to settle the case in advance of the incurring the expense of trial.

The parties may well be controlled by the local rules of the district court where the litigation is being conducted. In the wake of the Markman decision, several U.S. district courts have developed local rules governing the timing and conduct of Markman hearings. These rules should clearly be consulted early in order to plan litigation strategy.

The Markman hearing is likely the most important proceeding in a patent infringement case, short of the trial itself. The Markman hearing gives the parties the opportunity to present to the judge their view of the meaning of specific, important claim terms. A Markman ruling will give the parties a meaningful roadmap for the ongoing litigation, including a useful tool in assessing settlement options.