Brief for Honeywell International
When examining the case of Honeywell International, Inc. v. Hamilton Sundstrand Corporation, the court should consider what exactly should warrant estoppels to apply. Any small change in the claims resulting in the loss of the ability to use the doctrine of equivalents seems unfairly strict. Although even if the court chooses for this not to be considered, the equivalent was not foreseeable in this specific case and therefore the estoppel shouldn’t apply regardless. Going even further it can be reasoned that Hamilton Sundstrand Corporation’s patent does infringe on Honeywell International’s by the doctrine of equivalents.
To begin, estoppel principles should not be applied to all cases with claims being revised. There are a variety of reasons for the PTO to request a change in claim language according to the Warner-Jenkinson decision. It is then for the court to consider if that purpose warrants an estoppel. The purpose of an estoppel is to hold the inventor to the representations made during the application process. Therefore Honeywell should not have to surrender his ability to use the doctrine of equivalents because dependent claims were changed to independent claims including limitations that were not used before. Honeywell’s change in claims was made necessary by the cancellation of independent claims and the need to clarify the dependent claims associated with them in his improved surge control design. In no way was Honeywell trying to change the claims in his patent, it was just difficult to construct the same claims when changing them from dependent to independent.
Even if the estoppel principles are used they should not be used to form a complete bar against Honeywell. It is impossible to construct claims, with any number of attempts, in which no equivalent could be drawn without some use of the doctrine of equivalents. As Newman states, “language remains an imperfect fit for invention. The narrowing amendment may demonstrate what the claim is not; but it may still fail to capture precisely what the claim is.” Therefore I have come to the conclusion that the doctrine of equivalents should always be considered to some extent, but perhaps at a lesser level if estoppel principles are found to in affect.
Finally, Sundstrand’s product was unforeseeable thereby negating any estoppel. “Foreseeability only requires that one of ordinary skill in the art would have reasonably foreseen the proposed equivalent at the pertinent time.” The evidence of a L1011 system being developed for the purpose of controlling surge is generally accepted; however this only proves that Honeywell had knowledge of the surge problems. It doesn’t prove Honeywell could create a solution to the surge problem using inlet guide vanes. The L1011 system used a shock switch to control flow. From this it is not intuitive, as the district court claims, that inlet guide vane position was a foreseeable solution. It seems like a slightly exaggerated law, to both Judge Newman and myself, that a device created a decade later should be foreseeable. Where does this foreseeability end? How many years after your invention does it take for a new invention to no longer be foreseeable?
Assuming that the estoppel principles were not met and the doctrine of equivalents applies, it is quite obvious that Sundstrand’s device infringed on Honeywell’s. This is evidenced in the original court with a jury ruling willful infringement based on the doctrine of equivalents. Honeywell claimed technology to control airflow surge in auxiliary power units, using inlet guide vanes to control airflow and solve so-called “double solution” problem. Sundstrand claimed a surge control system that compares a flow-related parameter called DELPQP to a set point based on air inlet temperature and adjusts the surge bleed valve in response. This surge control device uses inlet guide vanes to determine specific actions in the system. Obviously the inlet guide vanes are used for the same means as in the Honeywell patent, even if the method to get there is slightly different. The Graver Tank ruling clearly states, based on Sanitary Refrigerator Co., that “if it performs substantially the same function in substantially the same way to obtain the same result,” then the doctrine of equivalents can be invoked. Graver Tank also states later that, “consideration must be given to the purpose for which an ingredient is used in a patent…. and the function which it is intended to perform. An important factor is whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was.” The function of the patents were essentially the same, and I am confident that anyone close to reasonably skilled in the art would know of the interchangeability of the part in question here.
In conclusion I urge the Supreme Court to consider the ways in which estoppels are applied and consider exactly how they are most affective in promoting the advancement of the art. I would also urge them to clarify what exactly is foreseeable relating to estoppels. In addition to all of this I would ask the court to see that Honeywell’s revised claims are not worth of an estoppel and a jury convicted Sundstrand of willful infringement, which is painfully obvious when considering the intended result of both patents.