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Write Broad Disclosures to Avoid Discouraging LanguageJune 26, 2006

June 22, 2006 – The Federal Circuit determined that the Honeywell, the holders of Patent No. 5,164,879 purposefully limited the scope of the claims thereby relieving rival ITT of patent infringement accusations.The claim in dispute related to a new fuel filter technology. Traditionally, car fuel filters were made with a polymer housing, however, after the advent of the electronic fuel injection (EFI) system, such fuel filters would break down and start leaking. The patentee, Honeywell International, discovered this problem could be avoided by providing an electrically conductive pathway made out of metal between the fuel filter and the vehicle’s metal frame to prevent the filter housing from accumulating an electrical charge from the increased fuel flow rate in the EFI systems. In its patent, Honeywell claimed a ‘fuel injection system component’ having ‘electrically conductive fibers’. The patent described stainless steel fibers as particularly suited for use in the invention, comparing them to conductive carbon fibers, the use of which was discouraged. The defendant manufactured ‘quick connects,’ which are structures that join the various components of a fuel injection system together, such as a fuel line to a fuel filter. The accused infringing product was a quick connect that had a polymer housing interlaced with electrically conductive carbon fiber. The court held that while the patent claimed a ‘fuel injection system component,’ it was limited to fuel filters. Using the patent’s specification to determine the meaning of the term, the court noted that on at least four occasions in the specification, the patentee referred to ‘this invention’ or ‘the present invention’ as a fuel filter, and the only drawing provided was of a fuel filter. Moreover, the written description contained no mention that a fuel filter was merely one preferred embodiment, and the discussion of problems in the prior art only referred to fuel filter leakage. Therefore, the court found the language in the specification to show that the invention was a fuel filter, not any other component of the fuel injection system. Based on this construction, there could be no infringement in this case. Honeywell admitted that fuel filters are not the same as ‘quick connects,’ and because the two perform different functions, there was no infringement under the doctrine of equivalents.Interestingly, the Federal Circuit also construed a second term, ‘electrically conductive fibers,’ even though its conclusions regarding ‘fuel system component’ were sufficient to affirm the lower court’s holding of no infringement. In multiple places in the specification, carbon fibers were ‘demeaned’ as being an inferior material for the claimed invention, going beyond expressing the patentee’s preference for one material over another, and that the repeated derogatory statements concerning one type of material were the equivalent of a disavowal of that subject matter from the scope of the patent claims. In the court’s words, ‘[i]f the written description could talk, it would say, ‘Do not use carbon fibers.” As a result, the accused products, which used carbon fibers, also did not possess this claim element. This case is illustrative of the care patent drafters must take to write a broad disclosure open to multiple embodiments of an invention. Importantly, this case suggests that it can be risky to refer to a preferred embodiment as ‘the invention,’ or to talk about non-preferred embodiments in a discouraging manner. To read the full decision, log on to

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