Background
Commil USA held a patent on a method for implementing short-range wireless networks — used in Wi-Fi and other wireless networking technologies. Cisco manufactured and sold networking equipment and was accused of inducing infringement by selling equipment that its customers used to practice the patented method. At trial, Cisco presented evidence that it had a good-faith belief that Commil’s patent was invalid, arguing this belief negated the knowledge element required for induced infringement under § 271(b).
The Supreme Court had previously held in Global-Tech Appliances v. SEB (2011) that induced infringement requires knowledge that the induced acts constitute patent infringement — meaning the defendant must know the patent exists and know the induced conduct constitutes infringement. The question in Commil was whether a belief that the patent is invalid negates this knowledge requirement.
The Court’s Holding
The Supreme Court held that a good-faith belief of invalidity is not a defense to induced infringement. The Court reasoned that infringement and validity are separate issues: a patent is presumed valid until proven otherwise, and whether a defendant believes the patent is invalid is a separate question from whether the defendant knows its conduct constitutes infringement. Allowing a belief of invalidity to negate the intent element of inducement would conflate these distinct concepts.
The Court distinguished the prior Global-Tech decision — which allowed a good-faith belief of non-infringement to negate induced infringement liability — because non-infringement goes to whether the induced acts actually constitute infringement, while invalidity is a separate affirmative defense that must be proven by clear and convincing evidence.
Key Takeaways
- A defendant’s good-faith belief that a patent is invalid is not a defense to induced infringement under § 271(b) — invalidity must be raised and proven as an affirmative defense, not used to negate the intent element of inducement.
- Good-faith belief of non-infringement (distinct from invalidity) can still negate the knowledge element of induced infringement — the Commil rule applies specifically to invalidity beliefs, not to beliefs about whether the conduct constitutes infringement.
- Defendants facing induced infringement claims should pursue invalidity challenges (IPR, reexamination, district court invalidity defenses) directly rather than relying on invalidity beliefs as a defense to the infringement liability itself.
- The distinction between infringement and validity — long fundamental to patent law — is reinforced by Commil: defendants cannot collapse the two by arguing that belief in invalidity excuses conduct that would otherwise constitute induced infringement.
Why It Matters
Commil USA v. Cisco clarified an important boundary in patent law: the line between the infringement analysis and the invalidity analysis. By holding that a good-faith belief of invalidity does not defeat induced infringement, the Supreme Court ensured that defendants could not sidestep induced infringement liability simply by asserting they believed the patent was invalid — a rule that could have allowed companies to induce infringement at scale while avoiding liability through a self-serving invalidity belief.
The decision had immediate practical consequences for companies — like major technology manufacturers — that routinely induce end-user customers to use products in ways that may practice patented methods. Such companies cannot escape induced infringement liability by arguing they believed the asserted patent was invalid; instead, they must mount a formal invalidity defense and prevail on it to avoid liability. This reinforced the importance of proactive patent clearance — obtaining formal opinions of counsel or pursuing IPR challenges — rather than relying on informal invalidity beliefs as a business risk management strategy.