September 2025 Patent infringement in the United States continues to evolve, particularly in how prosecution history impacts the interpretation of patent claims during the Infringement proceedings. A recent decision by the US Court of Appeals in Colibri v. Medtronic offers a compelling example of this trend, illustrating how choices made during patent prosecution can later affect enforceable rights.
In this case, the dispute centred on method claims for deploying an artificial heart valve. It raised critical questions about the doctrine of equivalents, estoppel, and legal consequences of amending claims during prosecution.
Background
Colibri Heart Valve LLC held a patent covering a method for implanting an artificial heart valve, specifically focusing on controlled and recoverable valve deployment. The patent originally included two independent claims: one involving pushing the valve out of a sheath, and another involving retracting the sheath to expose the valve.
During prosecution, the US Patent and Trademark Office (USPTO) rejected the method claim reciting “retraction” for lack of written description. In response, Colibri cancelled that claim, and the patent was issued only with the claim covering the “pushing” method.
Colibri later sued their competitors Medtronic Corevalve LLC, alleging that their devices induce surgeons to perform the patented method. Colibri argued that Medtronic’s devices used both pushing and retracting mechanisms, which according to the doctrine of equivalents falls within the scope of their patent. In particular, Colibri argued that “retracting” inherently involves “pushing” which was protected by their patent.
The jury at the district court’s proceedings sided with Colibri, awarding over $106 million in damages for induced infringement.
US Court of Appeals Decision
Medtronic appealed, arguing that Colibri’s cancellation of the “retracting” claim during prosecution triggered prosecution history estoppel, preventing them from asserting equivalence between “pushing” and “retracting”.
This time, the Court of Appeals agreed with Medtronic. It was established that the cancelled and retained claims were closely related, and that cancelling one communicated a narrowing message about the other. The court emphasized that Colibri has clearly distinguished the two methods during prosecution and could not now claim they were equivalent.
The court concluded that Colibri had narrowed its patent scope and could not broaden it through the doctrine of equivalents. As a result, the district court’s decision was reversed, and Medtronic was cleared of liability
Summary
Colibri v. Medtronic highlights a critical principle in US patent law: what is done during prosecution cannot be ignored in litigation. The case illustrates how prosecution history, especially claim cancellation, can limit the scope of patent protection and prevent later reliance on equivalence.
