Direct infringement
Direct infringement under 35 U.S.C. § 271(a) is the central liability rule of the Patent Act. It is a strict-liability tort: anyone who makes, uses, offers to sell, sells, or imports the patented invention without authority infringes, regardless of intent or knowledge. The harder questions concern who counts as the infringer when more than one person is involved in performing a method.
The rule
Direct infringement occurs when a person, without authority, performs one of the five infringing acts in 35 U.S.C. § 271(a) — makes, uses, offers to sell, sells, or imports — with respect to the patented invention, within the United States, during the term of the patent. Direct infringement is a strict-liability tort. The accused party's state of mind is irrelevant. The Supreme Court has confirmed that "direct infringement is a strict-liability offense," Global-Tech Appliances, Inc. v. SEB S.A., 563 U.S. 754, 761 n.2 (2011), and the Federal Circuit has restated the rule countless times. See, e.g., In re Seagate Technology, LLC, 497 F.3d 1360, 1368 (Fed. Cir. 2007) (en banc) ("Patent infringement is, in general, a strict liability offense").
Statutory and constitutional source
Section 271(a) provides:
Except as otherwise provided in this title, whoever without authority makes, uses, offers to sell, or sells any patented invention, within the United States, or imports into the United States any patented invention during the term of the patent therefor, infringes the patent.
The constitutional foundation lies in the Patent and Copyright Clause, U.S. Const. art. I, § 8, cl. 8, which grants Congress the power "[t]o promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries." The Patent Act of 1952, codified at Title 35 of the U.S. Code, exercises that power. See Title 35.
Indirect infringement is treated separately under § 271(b) (induced) and § 271(c) (contributory). Other related provisions reach extraterritorial conduct: § 271(f) addresses supply of components from the United States, § 271(g) addresses importation of products made by patented processes, and § 271(e) addresses certain pharmaceutical and Hatch-Waxman scenarios. See indirect infringement.
The framework the courts apply
Five infringing acts
Each of the acts in § 271(a) is independently sufficient. "Makes" reaches assembly or manufacture of the patented invention in the United States. "Uses" covers operating, employing, or putting the invention into service for its intended purpose. "Offers to sell" was added by the 1996 Uruguay Round Agreements Act and is interpreted under traditional contract-law principles. See Rotec Industries, Inc. v. Mitsubishi Corp., 215 F.3d 1246, 1255 (Fed. Cir. 2000). "Sells" reaches commercial sales, including transfer of title or delivery against consideration. "Imports" covers bringing the patented invention into the United States.
For system claims, the Federal Circuit has located "use" at the place where the user controls the system as a whole and obtains beneficial use of it. NTP, Inc. v. Research in Motion, Ltd., 418 F.3d 1282, 1317 (Fed. Cir. 2005). For method claims, "use" generally requires that every step of the method be performed.
Strict liability
Subjective intent, knowledge of the patent, and good-faith belief in non-infringement or invalidity are no defense to direct infringement. The accused infringer's state of mind matters for enhanced damages under § 284 and for indirect-infringement liability, but not for the underlying tort. Commil USA, LLC v. Cisco Systems, Inc., 575 U.S. 632, 639 (2015), reaffirmed that point: "[A] defendant's belief regarding patent validity is not a defense to a claim of induced infringement," and direct infringement is, a fortiori, no different.
Geographic scope
Section 271(a) is territorial. The infringing act must occur "within the United States" (or, for importation, the patented invention must cross the border). Conduct entirely abroad does not infringe a U.S. patent under § 271(a). See Microsoft Corp. v. AT&T Corp., 550 U.S. 437, 441 (2007). For sales, courts have looked to the location of the contracting parties and performance, including delivery. See Halo Electronics, Inc. v. Pulse Electronics, Inc., 831 F.3d 1369 (Fed. Cir. 2016) (post-remand) (analyzing situs of sale).
The single-actor rule and divided infringement
For method claims, direct infringement traditionally requires that a single actor perform all the steps. The "single-actor rule" was tightened in Muniauction, Inc. v. Thomson Corp., 532 F.3d 1318 (Fed. Cir. 2008), and reaffirmed by the Supreme Court in Limelight Networks, Inc. v. Akamai Technologies, Inc., 572 U.S. 915 (2014). Limelight held that there can be no liability for inducing infringement under § 271(b) where there is no underlying direct infringement under § 271(a) — that is, where no single party performs every step of the method.
On remand, the Federal Circuit, sitting en banc in Akamai Technologies, Inc. v. Limelight Networks, Inc., 797 F.3d 1020 (Fed. Cir. 2015) (en banc), expanded the circumstances under which one entity may be held responsible for the acts of another for purposes of § 271(a). The court held that direct infringement occurs when all method steps are attributable to a single entity, and that attribution can rest on either of two grounds: (1) the entity directs or controls the others' performance, including by conditioning participation in an activity or receipt of a benefit on performance of the method steps and establishing the manner or timing of that performance; or (2) the entities form a joint enterprise. Akamai, 797 F.3d at 1022–23.
The "directs or controls" prong is the more frequently litigated. After Akamai, a service provider that requires its customers to perform certain steps as a condition of receiving the service can be held liable for those customer-performed steps. See Eli Lilly & Co. v. Teva Parenteral Medicines, Inc., 845 F.3d 1357 (Fed. Cir. 2017) (applying Akamai to physician-patient context).
Joint enterprise
Joint-enterprise liability borrows from the Restatement (Second) of Torts § 491 and requires (1) an agreement, express or implied, among the members; (2) a common purpose; (3) a common pecuniary interest; and (4) an equal right to a voice in the direction of the enterprise. Akamai, 797 F.3d at 1023. The doctrine has been applied sparingly.
Burden and proof
The patentee bears the burden of proving direct infringement by a preponderance of the evidence. The infringement question is one of fact for the jury (or the court on a bench trial), reviewed for substantial evidence (jury) or clear error (bench). Where the underlying facts are undisputed, infringement may be resolved on summary judgment. See Fed. R. Civ. P. 56.
Proof typically requires element-by-element comparison of the construed claim to the accused product or process. See literal infringement. Where direct infringement is asserted on a divided-infringement theory, the patentee must show that all steps are attributable to a single accused infringer either through direction-or-control or through joint-enterprise proof.
Interaction with related doctrines
Direct infringement is the predicate for induced and contributory infringement. Without an underlying direct act, there can be no inducement or contribution. Limelight, 572 U.S. at 921. Direct infringement may be proved literally or under the doctrine of equivalents, but it must be proved.
Direct infringement interacts with the exhaustion doctrine: an authorized first sale of a patented article exhausts the patent rights as to that article, defeating direct-infringement claims arising from the buyer's later use, sale, or modification within the scope of the sale. See Impression Products, Inc. v. Lexmark International, Inc., 581 U.S. 360 (2017).
Direct infringement is also the subject of validity defenses: an invalid patent cannot be infringed. The full set of validity doctrines — anticipation, obviousness, written description and enablement, definiteness, and subject-matter eligibility — supplies grounds to defeat infringement allegations. Validity is presumed and must be overcome by clear and convincing evidence. Microsoft Corp. v. i4i Limited Partnership, 564 U.S. 91 (2011).
Practical notes
- Strict liability means that a customer or end user can be a direct infringer even when the alleged misconduct is the supplier's design choice. Patentees often pursue both direct and indirect theories simultaneously.
- For method claims involving customer participation, the Akamai direction-or-control test is now the central battleground. Whether a service provider "conditions" participation on customer performance and "establishes the manner or timing" of that performance is intensely fact-bound.
- For software or distributed-system claims, watch for divided-infringement issues at pleading. Defendants often move to dismiss where the complaint identifies multiple actors performing different steps.
- Geographic facts matter. Sales and offers can implicate § 271(a) even when the underlying product is manufactured abroad if a U.S. nexus exists; conversely, purely foreign sales generally fall outside § 271(a).
- Direct infringement of system claims under NTP may be located where the user exercises control, even if components reside in multiple jurisdictions.
- The good-faith-belief defense to inducement under Commil does not apply to direct infringement. Counsel should not conflate the two when advising on liability exposure.
Open questions
The full reach of the Akamai direction-or-control framework remains unsettled. Subsequent panels have applied the test in service-provider, doctor-patient, and software-customer contexts, but the exact degree of "conditioning" required varies across cases. The Federal Circuit has not yet resolved whether contractual obligations alone are sufficient or whether an enforcement mechanism is required.
Cross-border digital systems pose continued difficulty. As more patented systems span servers and users in multiple countries, the NTP and Microsoft v. AT&T framework strains under the weight of distributed architectures. Section 271(a)'s territorial limit and the situs-of-use analysis in particular remain ripe for further decision.
See also
- Literal infringementStandard test for whether the accused product practices the claim.
- Doctrine of equivalentsBackup theory for infringement.
- Induced and contributory infringementLiability of those who do not perform the patented invention themselves.
- Patent exhaustionFirst-sale defense.
- WillfulnessSubjective culpability for enhanced damages.
- Title 35 referenceStatutory framework for U.S. patent law.
Last reviewed: 2026