Homework 6: Due Monday April 4

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Brief in Support of Honeywell

The Doctrine of Equivalents states, “a product or process that does not literally infringe upon the express terms of a patent claim may nonetheless be found to infringe if there is ‘equivalence’ between the elements of the accused product or process and the claimed elements of the patented invention.” In this case, we are attempting to rebut the doctrine of prosecution history estoppel, which prevents a patent applicant from going back to the original patent filed and attempting to restructure claims to cover subject matter that was not used when initially filing for the patent, in order to claim infringement under the doctrine of equivalents. Under the doctrine of prosecution history estoppel, the applicant is not allowed to claim subject matter that could be considered to be equivalent and thus infringe the patent under the doctrine of equivalents.

The CAFC determined that the “rewriting of dependent claims into independent form coupled with the cancellation of the original independent claims creates a presumption of prosecution history estoppel.” The key to proving whether prosecution history estoppel is properly applied is examining why the claims in Honeywell’s original patent needed to be resubmitted. According to the case literature, the original patent claims were rejected due to obviousness in light of the prior art. Prosecution history estoppel may be applied when the reason for a change in the claim literature is in regards to patentability. Clearly, obviousness is related to patentability, so it cannot be argued whether it is appropriate to apply prosecution history estoppel. However, the amended claims did not narrow the equivalent element in question. “The district court had recognized that the element for which equivalency was charged – the inlet guide vanes used to adjust a set point to avoid surge – had not been narrowed.”

Why is it that the prosecution history estoppel is applied in a situation where the equivalence in question actually is not related to the claim that was narrowed? The subject matter surrendered in the claim revisions is most important in deciding whether the presumption of surrender is rebutted. If the “technological equivalent is embraced by subject matter that was relinquished during prosecution of the patent,” then the presumption has not been rebutted. To reiterate the earlier point, it was explicitly stated that equivalent art had nothing to do with subject matter surrendered from narrowing claims during the initial patent prosecution.

As stated in the dissent, it is very interesting that the district court declined to give a reasoning for the why the equivalence was both foreseeable and more than merely tangential in relation to the Honeywell patent. They were able to make this ruling without providing reason while also receiving testimony from expert witnesses that the technology used in the Sundstrand invention was not known at the time of the Honeywell invention. The Festo case is commonly referred to in regards to foreseeability. It is stated that foreseeability is a term used for “readily known equivalents” at the time of patent application. There is no evidence that Sundstrand’s equivalent, invented nearly a decade later, was readily known. Foreseeability does not include inventions that were unknown at the time. The majority ruling in the CAFC decided that if Honeywell knew about the Sundstrand problem, they probably could have figured out how to solve the problem in the same manner that Sundstrand did. This is a very subjective way to make a ruling. The majority is essentially saying that they are relying on a hypothetical situation to decide if an equivalent is infringing an original patent instead of just checking facts.

In concluding, we will state again that there is not enough fact in the case to determine that the Sundstrand did not infringe upon the Honeywell patent. It is undeniable that Honeywell narrowed a claim during the prosecution of the patent application in order to make it non-obvious and therefore, patentable in the eyes of the examiner. However, it is also unquestionable that the equivalent element question was not surrendered when the claims were narrowed. It cannot be stated more clearly that if a claim element is not the subject of an amendment, the presumption of history prosecution estoppel should not be made. The dissenting judge states, “Cancelling an independent claim is not an estoppel generating act as to elements whose scope was not amended or otherwise restricted during prosecution.” From the Warner v. Jenkinson case, we learned that equivalency should be determined element by element. Unfortunately, the majority ruling in this case against Honeywell does not follow the previous precedent. Just because an independent claim was cancelled, forcing Honeywell to make a dependent claim an independent claim does not mean that all dependent claims under the independent claim are surrendered subject matter.