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Issue 06/33 | July 7, 2006
Disparagement of Unpreferred Embodiments May Result in A Disavowal of Claim Scope

Patentees who highlight a preferred embodiment by disparaging alternative embodiments risk a claim construction that does not encompass the alternative embodiments. Practitioners should consider language descriptive of less preferred embodiments that is calculated not to surrender claim scope.

In Honeywell v. ITT et al., No. 05-1407 (Fed. Cir. June 22, 2006), the Federal Circuit affirmed the grant of summary judgment of noninfringement to ITT, based on a claim construction of "fuel injection system component" that was limited by the intrinsic evidence.

Honeywell's `879 patent is directed to a fuel injection system component that avoided the degradation of the fuel filter assembly because of "arcing" that occurred between electrostatic buildup in the fuel filter and the metal frame of the vehicle assembly. The claims recited a "fuel injection system component" comprising "electrically conductive fibers" for discharging electrostatic buildup. Defendants' accused "quick connects" (nut-like structures that join the various components of a fuel injection system together, such as a fuel line to a fuel filter) contained polymer housings interlaced with carbon fibers. The district court construed the fuel injection system component to mean a fuel filter, and electrically conductive fibers to include both metal and carbon fibers. Because defendants' quick connects were not fuel filters, the court granted summary judgment of noninfringement.

On appeal, the Federal Circuit rejected Honeywell's argument that "fuel injection system component" was not limited to a fuel filter. According to the court, the specification is the single best guide to interpreting patent claims and the Honeywell's `879 specification referred to "the invention" as a fuel filter at least four different times. It was irrelevant that applicants argued for a broader meaning during prosecution – arguments cannot contradict or enlarge the clear language of the specification.

The Federal Circuit disagreed, however, that "electrically conductive fibers" could be construed to encompass carbon fibers. Because patentees "demeaned" the properties of carbon fibers in the specification relative to stainless steel fibers, the Federal Circuit considered the statements a disavowal of claim scope. The Court rejected patentee's arguments that the specification was merely expressing a preference for stainless steel fibers and not disavowing carbon fibers:

the patentee informed its readers specifically why carbon fibers would not be suitable as "electrically conductive fibers" in the claimed invention. If the written description could talk, it would say, "Do not use carbon fibers." There is no other way to interpret the written description's listing of all the reasons that metal fibers fare better than carbon fibers for use in the claimed invention, even though both materials are electrically conductive.
Patentees disclosing alternative embodiments in a specification who denigrate the properties of one relative to the others in an attempt explain a preferred embodiment risk disavowal of the "less preferred" embodiment depending on the choice of language used.

Please visit http://media.aplf.org/rm/20060707-public/honeywell.pdf for a copy of the case for your reference.


To discuss these topics further, please feel free to contact the author, Michael R. Dzwonczyk (mdzwonczyk@sughrue.com), at Sughrue Mion, PLLC in Washington DC, USA.

The information contained in this email is provided for informational purposes only and does not represent legal advice. Neither the APLF nor the author intends to create an attorney client relationship by providing this information to you through this message.

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