Brief for Honeywell (JWB)

Noting the facts of the case, it is clear that the Court of Appeals erred in ruling non-equivalence in Honeywell International, Inc. v. Hamilton Sundstrand Corporation (2008). The possibility that Sundstrand’s invention was equivalent to Honeywell’s patent was never even really considered; instead, the court focused entirely on whether or not the doctrine of equivalence can even be applied due to prosecution history estoppel. Ultimately, Honeywell was barred from asserting the doctrine of equivalence to prove infringement due to the fact that independent claims were removed from the original patent application. However, it is clear that this removal of claims does not constitute an estoppels case. For the sake of clarity, it would be helpful to review what the PTO rejected in the original application. The original application was initially rejected due to 35 U.S.C. § 121, which states that “If two or more independent and distinct inventions are claimed in one application, the Director may require the application to be restricted to one of the inventions.” In other words, the PTO thought more than one invention was being claimed. To overcome this rejection, Honeywell simply added the ‘194 patent to its application as a divisional of the application of the original ‘893 patent. This is a perfectly legal process, outlined in detail in U.S. Code, and did not require a surrender of subject matter. The issue develops with the independent claims of this application. The issued patent contains independent claims that require the APU to include IGVs. However, before the split into ‘893 and ‘194, the original ‘893 application contained these claims as dependent claims, referencing independent claims that made no mention of IGVs or any use of the position of these guide vanes in the surge control system. It was these independent claims that were rejected as a result of obviousness in light of the prior art. The dependent claims (which included IGVs) were allowed to be rewritten as independent claims. The fact of the matter is that the claims that were surrendered in the original application made no reference to IGVs, which are the main contention of the infringement case. If subject matter was surrendered by deleting these original independent claims, it was not related to IGVs, and therefore IGV equivalents should not be barred due to prosecution history estoppel. The dissenting judge on the case made note of this inconsistency as well, arguing that “although the limitation at issue (the inlet guide vanes used to control surge) had not been the subject of amendment, argument, or any other form of restriction, the court held that all equivalent guide vanes were presumed surrendered, not simply equivalents presumptively barred by prosecution history estoppel.” There was no issue of obviousness and prior art with the IGVs, and there was no amendment to the patent application to claims involving IGVs, aside from the fact that dependent claims were rewritten as independent claims. Such a rewrite does not change the subject matter involved. The subject matter of the IGVs was never amended, and was thus never surrendered in any way. The next issue involves whether or not Sundstrand’s solution to the “double solution” problem was foreseeable to Honeywell at the time of the patent application. The goal of the principle of foreseeability is “to ensure that the claims continue to define patent scope in all foreseeable circumstances, while protecting patent owners against insubstantial variations from a claimed element in unforeseeable circumstances.” However, this principle seems to render the doctrine of equivalence moot. In essence, the principle requires that any foreseeable equivalent should be claimed by the patent application, and if it’s not, then the doctrine cannot be applied. The doctrine of equivalence is supposed to protect against non-literal infringement, and the principle of foreseeability seriously hinders such a purpose. Equivalents are still equivalent, regardless of whether they are foreseeable and claimed in the original patent. By not claiming foreseeable equivalents, Honeywell is in no way expanding the claims of their patent. Additionally, the district court declined to give reasoning for its finding that Sundstrand’s solution was foreseeable, stating that the record was “too extensive and complex” for the courts to identify the facts and that it would be “unduly burdensome” to explain which evidence it credited as the foundation of the finding. This vague ruling does not seem to be enough to rule foreseeability, and it is a slippery slope of lack of accreditation. It seems unjust to Honeywell to refuse to give reasoning behind the ruling.