Federal Circuit Applies Prosecution History Estoppel Based on Claim Cancellation

The US Court of Appeals for the Federal Circuit recently held that cancellation of a claim during prosecution may give rise to prosecution history estoppel, precluding the patentee from recapturing the surrendered subject matter under the doctrine of equivalents.

In Colibri Heart Valve LLC v. Medtronic CoreValve LLC, Colibri asserted US Patent No. 8,900,294 (the ’294 patent), which describes a method for implanting a replacement heart valve with the option to reposition the valve if misaligned.[1] Colibri alleged that Medtronic’s Evolut line of replacement heart valves infringed a method claim of the ’294 patent.[2] During prosecution of the ’294 patent, Colibri included two independent claims directed to different deployment mechanisms.[3] The first independent claim required deploying a portion of the replacement heart valve device by “pushing out” a pusher member of a delivery system from a moveable sheath. The second independent claim required deploying a portion of the replacement heart valve device “retracting” the moveable sheath to expose a portion of the replacement heart valve device.[4]

Other than this key distinction, the claims were identical. The examiner rejected the second independent claim for lacking written description support—particularly, the element requiring retraction of the moveable sheath—and Colibri cancelled the second independent claim.[5] The first independent claim ultimately issued.[6]

Medtronic’s Evolut line of replacement heart valves, the allegedly infringing devices, use a retracting sheath mechanism[7]—similar to the cancelled second independent claim.

Colibri then filed suit for infringement of the ’294 patent. During the claim construction proceedings, the parties disputed the term “pushing out the pusher member from the moveable sheath.”[8] Colibri proposed that the phrase meant a “pushing force is applied to the pushing member in a direction outwards from the moveable sheath,” and Medtronic proposed the phrase meant “pressing against the pusher member with a force that moves the pusher member out of the moveable sheath.”[9] The court adopted Medtronic’s proposed construction.

Colibri successfully argued that under the doctrine of equivalents, Medtronic’s partial-deployment method of retracting the moveable sheath is equivalent to the claimed partial-deployment method of applying a force to push the stent out of the moveable sheath, ultimately securing an infringement verdict.[10] Medtronic moved for judgment as a matter of law (JMOL) on the ground, among others, that Colibri’s equivalents claim was barred by prosecution history estoppel, but the court denied Medtronic’s motion.[11]

On appeal, the Federal Circuit disagreed and reversed denial of Medtronic’s JMOL motion, broadly holding that cancellation of claims can give rise to prosecution history estoppel because (1) the asserted equivalent did not differ distinctly from what was recited in the cancelled second independent claim[12] and (2) cancelling a claim in favor of another claim that has mostly identical features is effectively a narrowing amendment.[13]

The Federal Circuit’s analysis relies on the principle that a patentee who surrenders claim scope, regardless of the mechanism employed, cannot later recapture that scope by asserting it is covered under another claim’s doctrine of equivalents.[14] The Federal Circuit emphasized that surrender occurs whenever the patentee communicates a narrowing of the claimed invention to a person of ordinary skill in the art, and that such narrowing is not confined to the specific claim amended or cancelled, but extends to all claims in the patent.[15]

The Federal Circuit found that Colibri’s cancellation of the second independent claim constituted a narrowing amendment—effectively imparting the narrowing effect to the first independent claim—because the terms “pushing out” and “retracting” that appeared in the two independent claims were “such intertwined terminology” that canceling one claim necessarily communicated that the scope of the other claim had narrowed.[16]

The Federal Circuit also dismissed arguments that cancellation of a separate and unasserted claim cannot have an estoppel effect on the asserted claim, calling such arguments “an entirely formal point” when “governing law precludes making formalities determinative, to the exclusion of substantive relationships that would be understood by relevant readers.”[17] The Federal Circuit pointed to the US Supreme Court’s decision in Festo where the Court noted that “Estoppel arises when an amendment is made to secure the patent and the amendment narrow’s the patent’s scope.”[18]

KEY TAKEAWAYS

The Federal Circuit’s decision[19] carries important implications for both patentees and accused infringers. Practitioners should treat every claim modification as potentially having a substantive effect on all claims as a whole. Practitioners should also appreciate that claim cancellations may have prosecution history estoppel ramifications on the remaining claims of an application. Indeed, the ruling[20] is a stark reminder that surrendering claim scope during prosecution—whether through amendment or cancellation to any claim—may foreclose reliance on the doctrine of equivalents to capture that scope in litigation for any claims in the patent. Once claim scope has been surrendered—whether through amendment or cancellation—recapture under the doctrine of equivalents is likely barred if the subject matter at issue is deemed substantively linked to what was surrendered.

For accused infringers, the decision provides a clear avenue to challenge assertions of equivalence when the patentee’s prosecution actions, even in relation to similar but unasserted claims, demonstrate intentional narrowing or surrender of claim scope.