What is the difference between direct and indirect patent infringement?

Patent infringement under U.S. law falls into two broad categories: direct infringement and indirect infringement. The distinction shapes who is liable, what the plaintiff must prove, and what conduct is worth monitoring in a freedom-to-operate or litigation context.

Direct infringement

Direct infringement is the baseline. Under 35 U.S.C. § 271(a), whoever without authority makes, uses, offers to sell, or sells any patented invention within the United States, or imports any patented invention into the United States during the term of the patent, infringes the patent.

The statute covers five acts: making, using, offering to sell, selling, and importing. Each is independently actionable. A company that manufactures a patented product without authorization infringes under § 271(a) even if it never sells the product.

The text of § 271(a) contains no knowledge or intent requirement. A party who unknowingly manufactures a product that reads on every element of a valid claim nonetheless commits direct infringement. This distinguishes direct infringement from the intent-dependent indirect theories described below.

Indirect infringement

Indirect infringement occurs when a person actively causes someone else to infringe on a patent. The accused indirect infringer does not personally perform the infringing act; instead, liability attaches because of the role that party played in enabling or encouraging a direct infringer.

Congress codified two forms of indirect infringement: induced infringement under § 271(b) and contributory infringement under § 271(c).

The shared prerequisite

To establish liability for either type of indirect infringement, a plaintiff must first show that there is an underlying act of direct infringement by a third party. If no direct infringement occurred, an indirect infringement claim cannot survive, regardless of how culpable the defendant's conduct appears. This threshold requirement gives defendants in indirect-infringement cases a structural defense: prove no direct infringer exists and the claim fails before reaching intent.

Induced infringement (§ 271(b))

Under 35 U.S.C. § 271(b), whoever actively induces infringement of a patent shall be liable as an infringer. An induced infringement claim requires a further showing that the defendant knowingly induced infringement by someone else and possessed the specific intent to encourage another's infringement.

The knowledge requirement has been sharpened by the Supreme Court. In Global-Tech Appliances, Inc. v. SEB S.A., 563 U.S. 754 (2011), the Court held that induced infringement under 35 U.S.C. § 271(b) requires knowledge that the induced acts constitute patent infringement. A defendant must know of the patent and know that the conduct it is encouraging amounts to infringement.

Global-Tech also established that willful blindness satisfies the knowledge requirement. Willful blindness requires that the defendant subjectively believe there is a high probability that a relevant fact exists and take deliberate actions to avoid learning of that fact. Engineering ignorance is not a safe harbor: a party that deliberately avoids confirming the existence of a relevant patent can be treated as having actual knowledge.

Practical examples of inducing conduct include providing installation instructions, user manuals, or marketing materials that direct customers to use a product in a way that practices every element of a patented claim.

Contributory infringement (§ 271(c))

Contributory infringement covers selling or importing a component constituting a material part of a patented invention, knowing it to be especially made or especially adapted for use in an infringement and not a staple article or commodity of commerce suitable for substantial noninfringing use. A plaintiff claiming contributory infringement must show the defendant sold a component of a patented machine or process that the defendant knew was created to infringe on a patent.

The staple article limitation is the key boundary. If an article can serve both infringing and lawful purposes, contributory infringement liability does not apply because a component that is a staple article suitable for substantial noninfringing use falls outside the scope of § 271(c). General-purpose parts with legitimate commercial uses do not trigger contributory liability even when the seller knows some buyers will use them to infringe.

Comparison at a glance

Practical notes

• Indirect infringement plaintiffs must build a direct infringement record first. There is no induced or contributory infringement without an identifiable party who has committed a direct infringing act. Plaintiffs asserting indirect theories should identify and document the direct infringers before pivoting to the secondary actor.

• The same conduct can give rise to both induced and contributory liability. A company that manufactures a non-staple component and simultaneously provides instructions directing end users to assemble it in a way that infringes may face claims under both § 271(b) and § 271(c) on the same set of facts.

• Knowledge timing matters for indirect claims. Because indirect infringement requires knowledge of the patent, the date on which the defendant first learned of the asserted patent is a key fact in litigation. Actual notice from the patent holder, publication of the patent, or marking of patented products can all establish the relevant date.

• Direct infringement can occur without any commercial purpose. Using a patented invention privately and non-commercially, with no sale or offer to sell, is still direct infringement under the plain text of § 271(a), which covers "uses" of a patented invention without any carve-out for private use.

• Willful blindness defeats engineered ignorance in indirect cases. A party that suspects a patent may exist and deliberately avoids confirming it does not insulate itself from an induced infringement claim. The Global-Tech standard closes the deliberate-ignorance loophole by treating willful blindness as equivalent to actual knowledge.