In Honeywell Int’l Inc. v. Hamilton Sundstrand Corp. (Fed. Cir. June 2, 2004), the Federal Circuit held that a presumption of prosecution history estoppel is created with respect to a patent claim limitation originally recited in a dependent claim and omitted from the independent base claim, when the dependent claim is rewritten into independent form to obtain allowance and the independent base claim is canceled.Honeywell sued Sundstrand for infringement of patents directed to an aircraft auxiliary power unit:  a small gas turbine engine usually located in the tail section of an airplane.  All the independent claims asserted by Honeywell against Sundstrand had been originally filed as dependent claims, and were rewritten into independent form during patent prosecution.

Each of Honeywell’s asserted patent claims requires that the auxiliary power unit include inlet guide vanes, and that a surge bleed valve operate as a function of inlet guide vane position.  Representative claim limitations at issue follow.

A gas turbine engine accessory power unit having a fluctuating compressed air supply demand, said accessory power unit comprising:

(a)        a compressor having adjustable inlet guide vanes;

…

(c)        surge bleed means operable to exhaust from said duct means a selectively variable quantity of air to assure at least a predetermined minimum flow rate through said duct means and thereby prevent surge of said compressor;

…

(e)        comparator means for receiving said sensing means output signal and generating an error signal representing the difference between the sensed value of said parameter and a desired value thereof, said comparator means having an adjustable control set point representing said desired value of said parameter;

(f)        means for transmitting to said comparator means a reset signal for varying said set point as a function of the position of said inlet guide vanes in accordance with a predetermined reset schedule; and

(g)        control means for receiving said error signal and transmitting to said surge bleed means a control signal to operate said surge bleed means….

Honeywell’s asserted claims had been originally filed as dependent claims that recited the inlet guide vane limitation.  The independent base claims for these dependent claims did not recite the inlet guide vane limitation.  The Patent Examiner had rejected the original base claims as obvious in light of the prior art, but indicated that the dependent claims would be allowable if rewritten into independent form including all the limitations of the base claims.  In response, the rejected base claims were canceled and the dependent claims were amended to expressly incorporate the limitations of the base claims.  These amended claims issued as the asserted claims.

At the district court, Sundstrand argued that:

• the asserted claims had been narrowed by amendment; and
• prosecution history estoppel barred all equivalents for the inlet guide vane limitation.

In rejecting Sundstrand’s motion for summary judgment on prosecution history estoppel, the district court held that:

• the elements at issue were not amended in rewriting the dependent claims into independent form; and
• Honeywell did not give up an embodiment of the invention with the inlet guide vane limitation.

The jury found that Honeywell’s patents were valid, were not literally infringed by Sundstrand, and were infringed by Sundstrand under the doctrine of equivalents.  The district court entered judgment against Sundstrand.

The Federal Circuit initially heard this appeal as a panel, and subsequently sua sponte ordered en banc review.  The only infringement charge at issue was under the doctrine of equivalents, since Honeywell had conceded that the inlet guide vane limitation was not literally met by Sundstrand’s device.  Honeywell and Sundstrand disputed the function of the inlet guide vanes required by the claims, and whether the position of the inlet guide vanes in the accused device performs an equivalent function.

A presumption of surrender of equivalents arises, stated the Federal Circuit, if the rewriting of the dependent claims into independent form, along with the cancellation of the original independent claims, constitutes a narrowing amendment.  In this regard, the Federal Circuit quoted Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 736-37 (2002):

The PTO might require the applicant…to rewrite a dependent claim as an independent one….

…We must regard the patentee as having conceded an inability to claim the broader subject matter or at least as having abandoned his right to appeal a rejection. In either case estoppel may apply.

The fact that the scope of the rewritten claim has remained unchanged, the Federal Circuit concluded, will not preclude the application of prosecution history estoppel if, by canceling the original independent claim and rewriting the dependent claims into independent form, the scope of subject matter claimed in the independent claim has been narrowed to secure the patent.

The Federal Circuit stated that:

• when a claim is rewritten from dependent into independent form; and
• the original independent claim is canceled;
• the surrendered subject matter is defined by:
• o the cancellation of independent claims that do not include a particular limitation; and
• o the rewriting into independent form of dependent claims that do include that limitation.

The Federal Circuit therefore held that:

• Honeywell presumptively surrendered all equivalents to the inlet guide vane limitation; and
• Honeywell is presumptively estopped from recapturing equivalents to the inlet guide vane limitation.

The Federal Circuit remanded to the district court the issue of whether Honeywell can overcome the presumption of surrender of equivalents.  All the judges except Judge Newman, who filed an opinion dissenting in part, joined in the opinion for the court filed by Judge Dyk.

June 4, 2004

Text Copyright © 2004 Bob Brill et al.

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