Commil United States, LLC v. Cisco Sys., Inc.
The Court ruled that a company's good-faith belief that a patent is invalid is not a defense to a claim that it induced someone else to infringe that patent.
The decision keeps the legal question of whether a patent was infringed separate from the question of whether it is valid, preserving other established routes for challenging a patent's validity instead of letting a defendant's private belief substitute for those routes.
“The scienter element for induced infringement concerns infringement; that is a different issue than validity.”
The majority's core reasoning that infringement and validity are separate legal questions.
How it got here: After two jury trials finding Cisco liable, the Federal Circuit affirmed in part but ruled the trial court wrongly excluded Cisco's invalidity-belief evidence; the Supreme Court took the case to resolve that question.
The Case in Depth
What happened
Commil holds a patent on a method for building wireless networks. It sued Cisco, a maker of networking equipment, claiming Cisco both directly infringed the patent itself and induced its customers to infringe by selling them the equipment. At trial Cisco argued it believed in good faith that Commil's patent was invalid, and tried to introduce evidence supporting that belief as a defense to the inducement claim.
The question before the Court
If a company believed in good faith that a patent was invalid, could that belief excuse it from liability for talking others into infringing it?
The Court's answer
No — the Court ruled that a defendant's good-faith belief that a patent is invalid does not excuse it from liability for inducing someone else to infringe that patent. Induced infringement requires proof that the defendant knew about the patent and knew the acts it encouraged actually amounted to infringement. A belief about validity addresses a completely different legal question and doesn't speak to that knowledge requirement at all.
Allowing such a defense would also undercut the long-standing presumption that an issued patent is valid, letting defendants sidestep the demanding evidence standard normally needed to prove invalidity. Companies that genuinely believe a patent is invalid still have proper ways to challenge it directly, such as asking the Patent Office to reexamine it or filing a declaratory judgment lawsuit, rather than raising the belief as a shortcut defense in an inducement case.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Companies accused of encouraging others to use a patented technology can no longer avoid liability simply by claiming they thought the patent was invalid. They must instead challenge validity through the recognized channels, such as reexamination or a declaratory judgment suit. This preserves the presumption that issued patents are valid and keeps patent-infringement trials focused on infringement, not scattered validity arguments.
What changes now
The case goes back to the lower courts for further proceedings, including a new trial on inducement using the correct knowledge standard from Global-Tech. Cisco can still challenge the patent's validity through the normal channels, such as the reexamination proceeding it already pursued, but it cannot use a good-faith belief in invalidity as a defense to the inducement claim itself. This is a final merits ruling, not a temporary order.
What this does not decide
The Court did not decide whether Cisco is actually liable for induced infringement on remand, nor did it disturb the separate ruling that the original jury instructions used the wrong 'knew or should have known' standard. It also left open all normal ways of challenging a patent's validity, such as reexamination or a declaratory judgment suit.
Concurrences and dissents
Concurrence in part — Justice Thomas
Justice Thomas joined the Court's opinion only as to Parts II-B and III, meaning he agreed with the ruling that belief in invalidity is not a defense to induced infringement and with the discussion of frivolous litigation safeguards, but did not join the Court's discussion reaffirming and explaining Global-Tech's knowledge requirement in Part II-A.
Dissent — Justice Scalia
“It follows, as night the day, that only valid patents can be infringed.”Scalia's central objection that infringement is impossible without a valid patent.
Justice Scalia agreed that induced infringement requires knowledge that the induced acts infringe, but argued that because only a valid patent can be infringed, a good-faith belief that a patent is invalid necessarily means a person cannot know they are causing infringement. He rejected the majority's four arguments as unpersuasive, particularly criticizing its reliance on 'practical reasons,' and would have held that a good-faith invalidity belief is a valid defense to induced infringement.
How the Court got there
The legal reasoning, step by step
- The Court reaffirmed its earlier ruling in Global-Tech that a company can only be liable for encouraging infringement (called induced infringement) if it knew about the patent and knew that the acts it encouraged actually amounted to infringement — mere carelessness is not enough.
- The Court explained that infringement and validity are treated as separate legal questions under the Patent Act, each with its own defenses; whether a patent has been infringed does not depend on whether it turns out to be valid.
- Because the required mental state for inducement is knowledge that the induced acts infringe — not knowledge about validity — a belief that the patent is invalid does not speak to that mental state at all, so it cannot cancel out the intent requirement.
- The Court reasoned that treating invalidity-belief as a defense would undercut the long-standing presumption that an issued patent is valid, since it would let a defendant sidestep the demanding 'clear and convincing evidence' standard normally required to prove invalidity.
- The Court also noted practical concerns: allowing this defense would multiply the issues juries must sort through and make patent litigation more burdensome, when companies already have proper channels — like asking the Patent Office to reexamine a patent or filing a declaratory judgment suit — to challenge validity directly.
- The Court concluded that a defendant's belief about a patent's validity is not a defense to induced infringement, so the Federal Circuit's contrary ruling had to be set aside.
Doctrinal impact
Cases affected by this decision
Reaffirms Global-Tech Appliances, Inc. v. SEB S. A. (563 U. S. ___)
The Court leaned on Global-Tech's rule that induced infringement requires knowing the induced acts amount to infringement.