Herbert Markman and Positek, Inc. v. Westview Instruments, Inc. And Althon Enterprises, Inc.

Patent infringement analysis has two steps: first, the court determines the meaning and scope of the asserted claims; second, the factfinder compares the properly construed claims with the accused device. The appeal concerned the first step. The en banc court resolved conflicting Federal Circuit precedent by holding that a judge—not a jury—has both the power and the obligation to construe claim language.

A patent is an integrated written instrument that creates federally granted exclusionary rights. Because the claims define the scope of those rights, construing them is analogous to interpreting statutes and other public legal instruments. Uniform judicial construction gives both patentees and competitors a consistent, reviewable statement of the patent’s boundaries rather than allowing those boundaries to vary with different jury verdicts.

The court acknowledged that technical evidence, dictionaries, treatises, inventor testimony, and expert testimony may help a judge understand scientific principles, terms of art, and the state of the prior art. But that evidence assists the court in interpreting the patent; it does not transform claim construction into a factual question for the jury. A court may accept or reject extrinsic evidence to the extent it is helpful, but may not use it to vary or contradict the patent and prosecution history.

The court rejected Markman’s reliance on earlier Federal Circuit decisions suggesting that disputed claim terms could create jury-triable factual questions. It concluded that those cases lacked sound support and conflicted with Supreme Court authority treating the construction of patent claims as a judicial function.

The court held that its rule did not eliminate the jury right in infringement actions. The jury may still decide factual questions involved in comparing the court’s claim construction to the accused product. The court’s holding allocates only the legal task of determining what the patent claims mean to the judge.

The majority rejected the analogy to contract interpretation. In a contract dispute, factual questions may arise about the parties’ subjective intent or about terms outside an incompletely integrated agreement. Patent infringement litigation does not involve an agreement between the patentee and the accused infringer, and the inventor’s undisclosed subjective intent cannot alter claim scope.

The court found the statutory-interpretation analogy more apt. Like statutes, patents are public instruments that bind persons who did not participate in their creation. The proper inquiry is therefore the objective meaning conveyed by the public patent record—claims, specification, and prosecution history—not the private understanding of the inventor or other participants in the patenting process.

The claim itself supported the district court’s construction. Claim 1 requires a system able to "detect and localize spurious additions to inventory" and "spurious deletions therefrom." This language fits physical clothing moving through a dry-cleaning operation, because garments can be located, lost, added, or removed. It makes little sense if inventory means only cash or invoice totals.

The specification repeatedly described inventory as articles of clothing. It explained that the system monitored the status, location, and throughput of inventory; identified articles placed in inventory; and used bar codes to monitor the progress of articles through the dry-cleaning system. These descriptions confirmed that the invention was directed to controlling physical garments, not merely accounting for revenue or invoices.

The prosecution history reinforced that reading. To distinguish prior art, Markman represented that the system maintained a reconcilable inventory total by adding input articles and subtracting output articles and could localize irregular entry or exit of inventory articles. During reissue prosecution, he also described the original claims as involving tracking of individual garments or groups of garments.

Markman’s testimony and his patent-law expert’s opinion could not override the patent documents and prosecution history. Testimony about how a patent should be construed is legal opinion, and extrinsic evidence cannot contradict the meaning established by the intrinsic record. Westview’s product literature likewise could not redefine the scope of Markman’s claims.

A court reviewing judgment as a matter of law must apply the correct legal standard even when the jury was instructed under a different standard. Because claim construction is a legal issue, the district court properly corrected the jury’s implicit, contrary construction of "inventory."

It was undisputed that Westview’s system retained invoice numbers, dates, and cash totals but did not retain garment descriptions or track individual garments or groups of garments through the cleaning process. It therefore lacked the claimed capability to maintain an inventory total of clothing and to detect and localize spurious additions or deletions of clothing.

The district court should ideally have construed the claims before submitting infringement to the jury. Its failure to do so was harmless, however, because it later granted judgment as a matter of law after supplying the correct claim construction. Under that construction, Westview could not infringe claims 1 or 10.