Invalidity Opinions are not Admissible to Negate Induced Infringement

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The Supreme Court ruled in Commil USA, LLC v. Cisco Sys., Inc., that a belief of invalidity cannot be used as a defense to induced infringement. At present, both invalidity and non-infringement opinions can still offer protection to a potential infringer for other purposes. Given the intertwined relationship between invalidity and non-infringement opinions, the Commil decision raises a question as to other areas of patent law might soon be impacted.


By a 6-2 margin, the Supreme Court held that a “defendant’s belief regarding patent validity is not a defense to inducement.” Thus, Cisco’s opinion of invalidity was held to be inadmissible for the purpose of establishing a defense to induced infringement. The Court, however, refused to reach the same conclusion for an accused infringer’s belief of non-infringement. Thus, the Supreme Court has drawn a line between opinions of invalidity and opinions of non-infringement, at least as they pertain to induced infringement.

Arguments of the Parties

At the heart of the matter, Defendant Cisco argued that evidence of a good-faith belief that Plaintiff Commil’s patent was invalid should have been admissible as a defense to induced infringement. In particular, Cisco argued that because knowledge of infringement was required to show inducement, an opinion of invalidity could be used as a defense to inducement. Cisco reasoned that one cannot infringe an invalid patent, and therefore, one cannot knowingly infringe a patent that is believed to be invalid.

Commil (joined by the Government) argued that patents are presumed to be valid and that the knowledge of validity is a distinct element from the knowledge of infringement. Commil also argued “that only knowledge of the patent is required for induced in¬fringement.” This second argument appears to be aimed squarely at the use of a good faith belief of non-infringement as a defense to induced infringement.

Rationale of the Majority

The Court noted that past decisions had treated questions of infringement and invalidity as independent and alternative grounds. Further, the Court explained that “the issues of infringement and validity appear in separate parts of the Patent Act,” and that “induced infringement and validity are separate issues and have separate defenses under the act.” The Court next turned to policy rationales including concerns over the erosion of the presumption of validity, and the availability of alternative mechanisms to address patents that are believed to be invalid. These alternatives included declaratory judgement actions, inter partes review, ex parte reexamination, and raising the affirmative defense of invalidity.

The door, however, was left open for the use of non-infringement opinions as a defense to inducement allegations. The Court refused to endorse Commil’s proposition that mere knowledge of the patent would be sufficient to meet the knowledge requirement for showing inducement, reiterating that inducement “requires proof the defendant knew the acts were infringing.”

Are Validity and Infringement Always Separable?

At first blush, the decision appears to cleanly separate issues of validity from the knowledge prong of induced infringement. A closer look suggests that this blanket statement may not tell the entire story. For example, the Commil decision does not address a situation in which there is, at least arguably, a significant overlap between determinations of validity and determinations of infringement. As an example of a possible overlap, a claim can be found invalid if it is indefinite due to failure to define the scope of the invention with sufficient certainty. Would the Supreme Court have reached the same conclusion under the narrower argument that it is not possible to knowingly infringe a patent claim when the scope of the invention cannot be reasonably ascertained? In other words, is it possible to know that a claim will be infringed if the claim cannot be understood?

Invalidity Defense Gap

There may be situations in which a potential infringer reasonably believes a patent to be invalid, but cannot rely upon the identified alternative mechanisms for challenging the patent. For instance, a declaratory judgement action or an affirmative defense of invalidity require there to first be an actual case or controversy between the parties relating to that patent. Moreover, there are limits on grounds for challenging validity for both the inter partes review and ex parte reexamination processes. As explained in MPEP §§ 2609 and 2209, both inter partes review and ex parte reexamination processes are limited to prior art patents or printed publications. A patent can be held invalid for a variety of other reasons, such as when there is a sale of a product, the patent does not claim statutory subject matter under § 101, or when the patent claims are indefinite under § 112. To be sure, similar situations exist for direct infringement, and a potential infringer should be wary of finding itself in such situations irrespective of the type of infringement.

Knowledge Requirements in Other Areas

While the Commil decision does not purport to extend into other areas of patent law, it might nonetheless have a broader impact. For example, like the knowledge element in proving infringement by inducement, a finding of willful infringement also carries a knowledge requirement, albeit by a different standard. While the Commil decision does not discuss the use of invalidity opinions as a defense to willful infringement, it will be interesting to monitor future decisions in this regard. Particularly in view of the deference the Commil decision grants to the presumption of validity for patents.

Legal Opinions Still Have Value

While legal opinions can be useful tools for understanding and mitigating risks associated with patent infringement allegations, it is important to understand the purpose and limitations of different types of opinions, and to be mindful of potential changes in the law.

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