A relatively recent Supreme Court decision,Markman v. Westview Instruments, Inc.,517 U.S. 370 (1996), has resulted in the development of specialized claim construction procedures in federal district courts. These procedures vary from district court to district court and, in some cases, from judge to judge within a district court.

These procedures may include the production of a specialized pleading illustrating a party’s understanding of the definitions of the terms or phrases within the patent claims. The parties may also be required to present preliminary infringement contentions prior to beginning of discovery.

The court may also decide to hold a claims construction or “Markman” hearing in which the parties present evidence to support their understanding of the construction of the claims. Often, a parties’ expert and/or an inventor testifies at these hearings.

The construction of the claims is a very important factor in deciding the outcome of a patent case. Courts look at various forms of evidence in constructing patent claims. A body of case law has developed a hierarchy among the evidence.

The most important evidence is intrinsic evidence. Intrinsic evidence includes the plain meaning of the terms and phrases used in the claims themselves, the patent specification and the prosecution history of the patent.

Courts may also consider extrinsic evidence when the intrinsic evidence is ambiguous. Extrinsic evidence may include expert testimony and/or inventor testimony. Extrinsic evidence may also include prior art or publications that have not been considered by the Examiner. Extrinsic evidence also includes dictionary definitions and learned treatises.

Claim construction is a four-step process.
  • Step 1 - Determine the ordinary and customary meaning of the claim terms.
  • Step 2 - Review the specification to look for specific definitions of claim terms or areas where the patentee disavowed the scope of a claim term.
  • Step 3 - Review the prosecution history to determine if the terms at issue were altered during the prosecution of the patent.
  • Step 4 - Examine extrinsic evidence if appropriate.