The Basics of Patent Claim Construction

In Schindler Elevator v. Otis Elevator, the Federal Circuit Court of Appeals again re-visited the basics of patent claim construction. Understanding claim construction can seem daunting to clients—even lawyers. But the Federal Circuit Court never seems to tire of setting out the basic rules of claim construction to continue its educational efforts in this core area of intellectual property practice.

In this most recent case, the Schindler Elevator invention was a “smart” elevator that can recognize a specific user when he or she enters the building; then automatically sends an elevator car for the user; then takes the user a specific floor.

 The terms at issue on appeal were “information transmitter” and “information device.”  These were the parts of the invention that recognized an elevator user when he or she entered the building and transmitted the relevant information to the elevator.  The district court construed these terms to mean a system that would work “without requiring any sort of personal action by the passenger.”  By this definition, the patent only covered automatic elevators that did not so much as require the user to lift a finger to be recognized.

 On appeal, the Federal Circuit found this definition to be too narrow, and struck the words “without requiring any sort of personal action by the passenger” from the definition of the terms “information transmitter and “information device,” holding the district court had not interpreted the patent properly.

 A claim term is generally given its “ordinary and customary meaning,” which is “the meaning that the term would have to a person of ordinary skill in the art in question at the time of the invention.” Phillips v. AWH Corp.  To arrive at the “ordinary and customary meaning” of a patent claim term, the court evaluates (a) the words of the claim, (b) the patent specification, (c) the prosecution history, and (d) extrinsic evidence concerning relevant scientific principles, the meaning of technical terms, and the state of the art.

Words of the Claim

 The place to start in claim construction is the words of the claim.   The patent claim sets out the “metes and bounds” of the intellectual property description–the claimed invention.  Since the ultimate objective of claim construction is to ascertain the limits of the claimed invention, the words used in the claims themselves are of greatest importance.

•  Are the words of a claim specifically defined in the patent?  If so, this definition is usually accepted by the court.
• Do the claim words have a clearly-understood meaning to one of ordinary skill in the art? 
• What is the context in which the words are used in the particular claim sentence and in the overall claim paragraphs?  Does the context make common sense and consistent with the overall purpose of the patented invention?
•  How are the words used in other claims of the patent, and elsewhere throughout the patent?  Again, consistency is the key.  If the patent lawyer defined a word one way in the patent, it will mean the same thing throughout the patent.

 In the Schindler Elevator case, the Federal Circuit read the patent to allow the possibility of a transmitter “carried by an elevator user.” Carrying a transmitter is thus a type of “personal action” expressly allowed by the claims. The Federal Circuit reasoned that since the patent does not require the transmitter to be carried in any particular way, it was logically foreseeable that the user might raise his or her hand to activate the elevator.  Therefore, limiting the scope of the patent to an invention not requiring “any sort of personal action by the passenger” was too narrow.

 Patent Specification

 The patent specification is the part of the patent that shows various examples of how the invention can be enabled, or put into practice. 

The specification is a “reality check” on the intent of the inventor, limiting claims that extend beyond the examples (enablements) set out in the specification.  Therefore, the patent specification is always highly relevant to the claim construction analysis. Usually, it is dispositive; it is the single best guide to the meaning of a disputed term.

Turning again to the Schindler Elevator analysis, the Federal Court pointed out that he phrase “personal action” is used only once in the Schindler Elevator specification, in the following sentence:

The advantages achieved by the invention reside in the fact that the desired journey destination is communicated automatically to the elevator control by (1) the information transmitters carried by the elevator users or by (2) the recognition of features of the elevator users without any personal action being required by the passenger.

 Because the Schindler Elevator specification allowed for an information transmitter actually carried by the elevator user, the Federal Circuit reasoned that an information transmitter requiring no personal action was only one optional use of the device.  Therefore, logically, limiting the scope of the patent to an invention not requiring “any sort of personal action by the passenger” was too narrow.

 Prosecution History

Prosecution history is the entire patent file holding the communications back and forth between the inventor and the patent office during the patenting process.  Thus, if the inventor willingly narrowed the scope of his or her patent claim in order to get the patent approved by the patent office, this information will be contained in the file history (sometimes called the “file wrapper”).   

The purpose of consulting the prosecution history in construing a claim is to exclude any interpretation that was disclaimed during prosecution, thereby making the claim scope narrower than it would otherwise be.  Phillips at 1317.

 The doctrine of prosecution disclaimer attaches where an applicant, whether by amendment or by argument, “unequivocally disavowed a certain meaning to obtain his patent.”  An argument made to an examiner constitutes a disclaimer only if it is “clear and unmistakable.”

Turning back again to the Schindler Elevator case, the district court found statements in the prosecution history which describe the invention as operating “automatically, contactlessly, and independently of the orientation of the information transmitter.” The district court read these statements as unambiguously disavowing the use of a passenger’s hands for any and all purposes. The Federal Circuit Court disagreed. As in the specification, those terms modify actions that take place only after the passenger has brought the transmitter within range of the recognition device.  Therefore there was no “clear and unmistakable” disclaimer.

The Federal Circuit Court therefore modified the district court’s construction of “information transmitter” and “recognition device” by striking the phrase “without requiring any sort of personal action by the passenger” from each construction.

Extrinsic Evidence

Extrinsic evidence of the meaning of claim terms in a patent is found in things like dictionaries and professional treatises.  This is called “extrinsic” evidence because it is found “outside” the content of the patent itself.  Because extrinsic evidence is outside the content of the patent, it is the least reliable source of information as to a patent’s meaning, and is sometimes ignored by the parties in claim construction analysis.

Indeed, in the Schindler Elevator case, extrinsic evidence was not admitted by the parties at the Markman claim construction hearing, so the Federal Circuit did not address the extrinsic evidence factor of claim construction.   

Summary

Claim construction can be a daunting process, but the Federal Circuit Court of Appeals strives in case after case to re-visit the straightforward logic of its claim construction rules—rules that can be learned by anyone.