Patents

When Canceling a Claim Forfeits Equivalents: Colibri Heart Valve v. Medtronic

The Federal Circuit erased a $106M verdict, holding that canceling a broader claim during prosecution surrenders that subject matter for the doctrine of equivalents.

March 12, 2026
Transcatheter heart valve delivery device used in TAVR procedures
Colibri's method claims covered partially deploying a replacement heart valve so clinicians can reposition it before final release. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

In Colibri Heart Valve LLC v. Medtronic CoreValve, LLC, No. 2023-2153 (Fed. Cir. July 18, 2025) (precedential), the U.S. Court of Appeals for the Federal Circuit wiped out a roughly $106 million jury verdict and held that prosecution history estoppel barred Colibri’s only theory of infringement—the doctrine of equivalents. Writing for a panel that also included Judges Hughes and Stoll, Judge Taranto delivered an opinion with a deceptively simple but consequential teaching: a patentee can surrender subject matter not only by amending a claim, but by canceling a closely related claim in response to a rejection. The decision arose on appeal from the U.S. District Court for the Central District of California (No. 8:20-cv-00847, Carter, J.), and it reversed the district court’s denial of Medtronic’s motion for judgment as a matter of law.

At a glance

  • Patent: U.S. Patent No. 8,900,294, directed to methods of partially deploying a transcatheter replacement heart valve so a clinician can reposition or recapture it before final release.
  • Asserted claim 1 (originally prosecuted as claim 34) recited partial deployment by pushing a pusher member out of the moveable sheath.
  • Canceled claim 39 recited partial deployment by retracting the moveable sheath—and was canceled in response to a written-description rejection under 35 U.S.C. § 112.
  • Accused conduct: Medtronic’s Evolut TAVR systems deploy by retracting an outer sheath. Colibri pursued induced infringement under § 271(b), arguing Medtronic induced surgeons to practice the claimed method.
  • Theory at trial: Colibri abandoned literal infringement and proceeded only on the doctrine of equivalents, contending that retraction was equivalent to pushing.
  • Holding: Estoppel from canceling claim 39 surrendered the retraction territory; Colibri could not recapture it through equivalents. Verdict reversed.

Literal infringement was off the table—and that mattered

The structure of Colibri’s case is the first lesson. Claim 1 required affirmatively pushing the pusher member out of the sheath; the accused Evolut devices instead hold the valve stationary and retract the surrounding sheath. Those are mechanically distinct operations, and Colibri evidently concluded it could not prove that the accused method literally performed the “pushing” step. By trial, Colibri had dropped literal infringement entirely and bet its case on the doctrine of equivalents.

That tactical decision is unremarkable on its own—equivalents exists precisely to reach accused designs that achieve the same result by a slightly different route. But it left Colibri with no fallback. Once the court concluded that estoppel foreclosed the equivalents theory, there was nothing else to decide. The opinion is a reminder that the doctrine of equivalents is not a free-standing safety net; it is a doctrine hemmed in by the patentee’s own prosecution conduct, and a litigant who relies on it exclusively inherits all of that conduct’s limitations.

The doctrine of equivalents meets prosecution history estoppel

The heart of the decision is the interaction between the doctrine of equivalents and prosecution history estoppel. Under Warner-Jenkinson and Festo, when a patentee narrows a claim during prosecution for reasons related to patentability, a presumption arises that the patentee surrendered the territory between the original and amended claim—and that surrendered territory cannot be reclaimed through equivalents. The classic fact pattern involves an amendment to a claim that itself is later asserted.

Colibri extends that logic in a way that should make every prosecutor pause. Colibri never amended asserted claim 1. Instead, during prosecution it canceled a different independent claim—claim 39—after the examiner rejected it for lack of written-description support. Claim 39 had expressly claimed the retraction approach. The Federal Circuit held that this cancellation operated as a surrender of the retraction subject matter, and that the surrender could narrow the scope available to the unamended, retained claim 1.

The court’s rationale turned on the relationship between the two claims. As the panel framed it, estoppel “is not limited to subject matter surrendered during prosecution only through claim amendments and narrowing, but also is applicable to subject matter surrendered by wholesale cancellation of claims” where there is a “close substantive relationship between the cancelled and retained claims.” Claim 39 (retraction) and claim 1 (pushing) addressed the same partial-deployment method and were, in the court’s view, two sides of the same inventive coin. A skilled artisan reviewing the file would understand that giving up the retraction claim communicated something about the scope of what remained. Colibri could not surrender retraction to obtain its patent and then recapture retraction—Medtronic’s exact mechanism—by labeling it an “equivalent” of pushing.

Critically, Colibri did little to fight on the estoppel merits. It argued only that the presumption of surrender should not attach at the threshold; it did not invoke any of the recognized Festo rebuttals—tangentiality, unforeseeability, or some “other reason” why the narrowing should not bar the particular equivalent. Having lost the threshold argument, Colibri had no rebuttal left to make, and the presumption became dispositive. The opinion is therefore both a substantive expansion of estoppel and a procedural cautionary tale about preserving rebuttal arguments.

Induced infringement under § 271(b): a method claim’s added fragility

Because the ‘294 patent claimed a method of deployment performed in the operating room, Colibri could not accuse Medtronic of directly performing the steps. The asserted theory was inducement under 35 U.S.C. § 271(b): that Medtronic, by selling Evolut systems and instructing physicians, induced surgeons to perform the patented method. The jury accepted that theory and awarded approximately $106 million.

Inducement adds layers of proof—an underlying act of direct infringement by the physician, plus the inducer’s knowledge and specific intent. But here the estoppel ruling rendered all of that academic. If the underlying acts (retraction-based deployment) fall within surrendered territory, there is no direct infringement to induce, and the § 271(b) edifice collapses with it. The case is a clean illustration that an inducement claim is only ever as strong as the infringement theory underneath it. When that theory is the doctrine of equivalents and the equivalent has been surrendered, the inducement count is doomed regardless of how compelling the intent evidence might be.

Open questions

The opinion resolves the case but leaves the contours of “cancellation estoppel” unsettled. How “close” must the substantive relationship between a canceled and a retained claim be before cancellation narrows the survivor? The panel relied on the shared method and the directly complementary mechanisms (push versus retract), but it offered no bright-line test. Future disputes will turn on how readily courts find that a canceled claim “communicated” the scope of one that was never touched.

A second question is how the Festo rebuttals operate in the cancellation context. Because Colibri did not argue tangentiality or unforeseeability, the court had no occasion to decide whether a patentee can show that a cancellation was tangential to the asserted equivalent. The presumption-rebuttal architecture presumably carries over, but its application to canceled (rather than amended) claims remains untested.

Implications

  • Treat every cancellation as a potential disclaimer. Dropping a claim to expedite allowance can quietly forfeit equivalents scope for the claims that remain—especially sibling claims covering alternative ways of doing the same thing.
  • Diversify infringement theories. Litigants who jettison literal infringement and proceed solely on equivalents leave themselves exposed to a single estoppel ruling that ends the case.
  • Preserve the Festo rebuttals. Arguing only that the presumption should not attach—without preserving tangentiality, unforeseeability, or “other reason” arguments—forfeits the patentee’s best escape hatch.
  • Mind written-description rejections. A § 112 rejection that prompts canceling a mechanism-specific claim may surrender that mechanism for equivalents purposes, not merely for literal scope.
  • Method-claim plaintiffs are doubly exposed. Inducement liability evaporates entirely if the underlying equivalents theory is estopped.

Frequently asked questions

Does canceling a claim during prosecution always create estoppel? No. The Federal Circuit required a “close substantive relationship” between the canceled claim and the retained claim being asserted. Cancellation of an unrelated claim should not narrow an asserted claim. But where, as in Colibri, the canceled and retained claims cover complementary ways of performing the same method, cancellation can surrender the territory the dropped claim occupied.

Could Colibri have saved its verdict by arguing tangentiality? Possibly, but it never tried. Colibri argued only that the presumption of surrender did not apply at the threshold; it did not invoke any Festo rebuttal. The court therefore treated the surrender as unrebutted. Whether a tangentiality argument would have succeeded against a cancellation remains an open question.

Why did the inducement claim under § 271(b) fail? Inducement requires an underlying act of direct infringement. Colibri’s only infringement theory was the doctrine of equivalents, and the court held that estoppel barred it. With no direct infringement to induce, the § 271(b) claim—and the $106 million award resting on it—could not stand.

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