Brief support Hamilton Sundstrand versus Honeywell Intern. Anthony Schlehuber 901477539

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Brief in support of Hamilton Sundstrand in the case of Honeywell International Inc. v Hamilton Sundstrand Corp. (523 F.3d 1304)

In the district court, it was held that ‘Substantial evidence would have permitted a reasonable jury to conclude that the APS 3200 did not literally infringe elements 4(c) and 4(d) of the ‘194 patent.’ Since Hamilton’s invention does not directly infringe, Honeywell must rely on the doctrine of equivalents. However, in this case the doctrine of equivalents does not apply because the differences between Hamilton and Honeywell’s inventions were foreseeable. Additionally, an estoppel also prevents Hamilton from using the doctrine of equivalents to determine infringement.

Hamilton succeeded where Honeywell did not in that they solved the DELPQP problem in a way that would have been foreseeable to one skilled in the art. It is the burden of the patentee to take into account foreseeable equivalents and create claims that prevent their use. While Honeywell believes that using the position of the inlet guide vane to determine high or low flow conditions was not predictable, testimony by their expert proves that in fact it was known that using the vanes in this manner was known to potentially improve operating efficiency. Additionally, no technical barrier prevented Honeywell from improving their device in this manner at the time of their patent application. The district court ruled that it was quite intuitive that it was foreseeable in 1982-1983 and therefore precluded the use of the doctrine of equivalents.

An additional element that prevents the use of the doctrine of equivalents is the existence of prosecution history estoppels which prevents a patent owner from recapturing subject matter surrendered to acquire the patent. During the patent approval process, Honeywell’s claims were rewritten such that several initial independent claims were cancelled and other dependent claims were rewritten to be independent. Due to the change in claims a prosecution history estoppel exists. It is particularly pertinent in this case because one of the rewritten claims deals with the IGV position. In order to circumvent the estoppel, Honeywell needed to show that the equivalent would have been unforeseeable at the time of the narrowing amendment. However, as shown earlier, the equivalent was foreseeable and therefore the estoppel stands. Alternately, the estoppel can be removed if the rationale behind the narrowing amendment bares only a tangential relation to the equivalent in question. This doesn’t apply in this case either because the amendment does apply to the issue at hand. Therefore, none of the criteria have been met and the estoppel stands.

The doctrine of equivalence cannot be used because of both the foreseeable of the equivalent and the prosecution history estoppel. Both prevent the doctrine from being implemented, and since no direct infringement occurred Hamilton does not stand guilty of infringement.