Glossary of patent litigation terms

A working A–Z reference to the vocabulary of United States patent litigation: the doctrines, statutes, procedural devices, and shorthand that recur in district-court briefing, PTAB practice, and Federal Circuit appeals.

A

AIA (America Invents Act): The Leahy–Smith America Invents Act, Pub. L. No. 112-29, 125 Stat. 284 (2011). Most provisions took effect March 16, 2013. The AIA replaced the pre-AIA "first to invent" rule with a "first inventor to file" system, redefined the prior-art universe in 35 U.S.C. § 102, and created the inter partes review, post-grant review, and (now-sunset) covered business method proceedings administered by the PTAB.
Abandonment: Loss of patent rights by failure to prosecute an application or maintain the patent. During prosecution, an application is abandoned if the applicant fails to respond to an Office action within the statutory period (35 U.S.C. § 133). After issuance, a patent expires for failure to pay maintenance fees under § 41(b). Abandonment is distinct from disclaimer or dedication: an abandoned application can sometimes be revived on a showing that the delay was unintentional.
Abstract idea: A judicially created exception to patent eligibility under 35 U.S.C. § 101. Abstract ideas, laws of nature, and natural phenomena are not patentable. The Alice/Mayo two-step framework asks whether the claim is directed to an abstract idea and, if so, whether the additional elements transform it into a patent-eligible application. See § 101 eligibility.
Accused product: The product, process, system, or service that the patent owner alleges infringes one or more claims. The patent owner must identify the accused instrumentality with specificity in infringement contentions, mapping each claim limitation to a structure or step in the accused product. See literal infringement.
All-elements rule: An infringement requires that every limitation of an asserted claim be present in the accused product, either literally or under the doctrine of equivalents. Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17 (1997). The rule constrains the doctrine of equivalents: an equivalent cannot vitiate or read out a claim limitation entirely.
Anticipation: Invalidity for lack of novelty under 35 U.S.C. § 102. A claim is anticipated when a single prior-art reference discloses, expressly or inherently, every limitation of the claim arranged as in the claim. Anticipation is a question of fact. See anticipation.
Applicant: The party prosecuting a patent application before the USPTO. Under the AIA, the applicant may be the inventor or an assignee or other party to whom the inventor is under an obligation to assign. See 37 C.F.R. § 1.46.
Article III standing: Constitutional requirement that a plaintiff show injury in fact, causation, and redressability. In patent cases, the patentee or an exclusive licensee with all substantial rights can sue. A bare licensee cannot. See standing; Lone Star Silicon Innovations LLC v. Nanya Tech. Corp., 925 F.3d 1225 (Fed. Cir. 2019).
Assignor estoppel: Equitable doctrine barring an inventor who assigns a patent (and those in privity) from later challenging its validity in district court. Reaffirmed but narrowed in Minerva Surgical, Inc. v. Hologic, Inc., 594 U.S. 559 (2021): the doctrine applies only when the assignor's invalidity claim contradicts representations made in assigning the patent. It does not apply in IPR. See Arista Networks, Inc. v. Cisco Sys., Inc., 908 F.3d 792 (Fed. Cir. 2018).

B

Best mode (pre-AIA): Statutory requirement that the specification disclose the best mode contemplated by the inventor of carrying out the invention. 35 U.S.C. § 112(a). The AIA preserved best mode as a disclosure requirement but eliminated it as a defense in litigation: failure to disclose best mode cannot invalidate or render unenforceable an issued patent. 35 U.S.C. § 282(b)(3)(A). It remains relevant only as a basis for examiner rejection during prosecution.
Bilski machine-or-transformation: The "machine-or-transformation" test, articulated by the Federal Circuit en banc in In re Bilski and addressed by the Supreme Court in Bilski v. Kappos, 561 U.S. 593 (2010). A claimed process is patent-eligible if it is tied to a particular machine or transforms an article from one state to another. The Supreme Court held the test is a useful clue but not the sole test for § 101 eligibility. See § 101 eligibility.
Blocking patent: A dominant patent that prevents practice of an improvement covered by a later patent, even though the later patent is independently valid. In obviousness analysis, a blocking patent can rebut commercial-success secondary considerations because the absence of competition may reflect the blocking effect rather than non-obviousness. Acorda Therapeutics, Inc. v. Roxane Labs., Inc., 903 F.3d 1310 (Fed. Cir. 2018).
Broadest reasonable interpretation (BRI): Claim construction standard historically used by the USPTO during examination and, until 2018, in PTAB trials. The PTAB now uses the Phillips standard for IPR/PGR petitions filed on or after November 13, 2018. 37 C.F.R. § 42.100(b). BRI still applies during ex parte examination and reexamination.
Burden of persuasion: The ultimate burden of convincing the trier of fact. In an infringement suit, the patentee bears the burden of persuasion on infringement by a preponderance; the accused infringer bears the burden of persuasion on invalidity by clear and convincing evidence. Microsoft Corp. v. i4i Ltd. P'ship, 564 U.S. 91 (2011). The burden of persuasion does not shift.
Burden of production: The obligation to come forward with evidence sufficient to allow a reasonable factfinder to find for the producing party. Distinct from the burden of persuasion. In declaratory-judgment actions, the burden of production on infringement remains with the patentee even though the DJ plaintiff initiated the action. Medtronic, Inc. v. Mirowski Family Ventures, LLC, 571 U.S. 191 (2014).

C

CAFC (Court of Appeals for the Federal Circuit): The United States Court of Appeals for the Federal Circuit, established in 1982 with exclusive appellate jurisdiction over patent appeals from the district courts and the PTAB under 28 U.S.C. § 1295. See Federal Circuit.
Cease-and-desist order: An ITC remedy under 19 U.S.C. § 1337(f) that directs a respondent to cease unfair acts, including the sale of imported infringing articles already in the United States. Often issued together with an exclusion order. See ITC Section 337.
Certificate of correction: A USPTO mechanism under 35 U.S.C. §§ 254–255 to correct minor errors in an issued patent. Office mistakes are corrected without fee under § 254; clerical or typographical errors of the applicant under § 255 if the error is of "minor character" and the change does not require reexamination. Substantive scope-altering changes generally require reissue.
Claim construction: The process of determining the meaning and scope of patent claims. Claim construction is a question of law for the court (with subsidiary factual findings reviewed for clear error). See Markman v. Westview Instruments; Phillips v. AWH; claim construction doctrine; and Markman hearings.
Claim differentiation: Canon of claim construction that different claims are presumed to have different scope. The doctrine is strongest where one claim explicitly recites a limitation present only by implication in another. It is a guide, not an absolute rule, and yields to clear evidence of contrary meaning in the specification or prosecution history. See claim construction.
Claim charts: Tabular comparisons mapping each limitation of an asserted claim to a corresponding feature of the accused product (for infringement) or prior-art reference (for invalidity). Claim charts are a fixture of infringement contentions, invalidity contentions, IPR petitions, and expert reports. Local patent rules in EDTX, NDCA, and other districts impose specific timing and content requirements.
Comparable license: A license to the patent in suit, or to a technologically and economically comparable patent, used as a benchmark in calculating a reasonable royalty. The Federal Circuit requires that comparability be established before such licenses are presented to the jury. Lucent Techs., Inc. v. Gateway, Inc., 580 F.3d 1301 (Fed. Cir. 2009).
Compulsory counterclaim: Under Federal Rule of Civil Procedure 13(a), a counterclaim arising out of the same transaction or occurrence as the opposing party's claim must be pleaded or is forfeited. Invalidity and unenforceability counterclaims are typical compulsory counterclaims to an infringement suit; the accused infringer almost always pleads them.
Conception: The formation in the inventor's mind of a definite and permanent idea of the complete and operative invention, sufficiently developed that one of ordinary skill could reduce it to practice without undue experimentation. Burroughs Wellcome Co. v. Barr Labs., Inc., 40 F.3d 1223 (Fed. Cir. 1994). Under pre-AIA law, conception combined with diligence to reduction to practice could establish priority; under the AIA, the filing date controls.
Concurrent jurisdiction: Multiple tribunals' simultaneous authority to address the same dispute. ITC Section 337 investigations and parallel district-court actions over the same patents are a paradigm example: 28 U.S.C. § 1659 allows the district-court defendant to stay parallel proceedings during the ITC investigation. ITC determinations have no preclusive effect on district-court proceedings. Texas Instruments, Inc. v. Cypress Semiconductor Corp., 90 F.3d 1558 (Fed. Cir. 1996).
Contributory infringement: A form of indirect infringement under 35 U.S.C. § 271(c). One who sells a component of a patented machine or a material for use in a patented process, knowing it to be especially made for use in an infringement and not a staple article suitable for substantial non-infringing uses, is liable as a contributory infringer. See indirect infringement.
Covered business method (CBM, sunset 2020): A transitional AIA proceeding for patents claiming a method or apparatus for performing data processing in financial services. AIA § 18, Pub. L. No. 112-29, § 18, 125 Stat. 329. CBM review allowed challenges on grounds beyond IPR (including § 101 and § 112) but applied only to "covered business method" patents. The program sunset on September 16, 2020. New CBM petitions are no longer accepted.
Cuozzo: Cuozzo Speed Technologies, LLC v. Lee, 579 U.S. 261 (2016). The Supreme Court upheld the PTAB's then-use of the broadest-reasonable-interpretation standard in IPR and held that the Board's institution decision is generally non-appealable under 35 U.S.C. § 314(d), subject to narrow exceptions for constitutional challenges and questions outside § 314(a). See IPR.

D

Daubert: Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), codified in Federal Rule of Evidence 702. The trial court is the gatekeeper for expert testimony, evaluating whether the expert's methodology is reliable and the testimony is relevant. Daubert challenges to damages and technical experts are routine in patent cases; LaserDynamics, Inc. v. Quanta Computer, Inc., 694 F.3d 51 (Fed. Cir. 2012), illustrates the rigor applied to royalty experts.
Declaratory judgment: An action seeking a judicial declaration of non-infringement, invalidity, or unenforceability. The Declaratory Judgment Act, 28 U.S.C. §§ 2201–2202, requires an actual case or controversy. MedImmune, Inc. v. Genentech, Inc., 549 U.S. 118 (2007), softened the prior "reasonable apprehension of suit" test, holding that the totality of circumstances controls.
Definiteness: The requirement under 35 U.S.C. § 112(b) that claims "particularly point[] out and distinctly claim[]" the invention. The Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014), held that a claim is indefinite if, read in light of the specification and prosecution history, it fails to inform a person skilled in the art about the scope of the invention with reasonable certainty. See definiteness.
Design patent: A patent on the ornamental design of an article of manufacture under 35 U.S.C. § 171. Term is 15 years from issuance. Infringement is judged by the "ordinary observer" test (Egyptian Goddess, Inc. v. Swisa, Inc., 543 F.3d 665 (Fed. Cir. 2008) (en banc)). Damages are governed by 35 U.S.C. § 289, allowing the patentee to recover the infringer's total profit on the article of manufacture.
Direct infringement: Infringement under 35 U.S.C. § 271(a): making, using, offering to sell, selling, or importing a patented invention without authority. Direct infringement is a strict-liability tort; intent and knowledge are irrelevant. See direct infringement.
Disclaimer (claim, prosecution, terminal): "Claim disclaimer" under 35 U.S.C. § 253 surrenders one or more claims. "Prosecution disclaimer" describes statements during prosecution that surrender claim scope and bind later interpretation. "Terminal disclaimer" disclaims part of the patent term to overcome obviousness-type double patenting and ties enforceability to common ownership.
Discovery: Pretrial exchange of information governed by Federal Rules of Civil Procedure 26–37 and local patent rules. Patent discovery centers on technical documents, source code, sales and financial data, license agreements, and depositions of inventors, fact witnesses, and experts. See discovery.
Divisional application: An application filed under 35 U.S.C. § 121 to claim an invention not elected in response to a restriction requirement in the parent. A divisional benefits from the parent's filing date and is shielded from § 121 double-patenting attacks based on the parent.
Doctrine of equivalents: A judicial doctrine allowing a finding of infringement when the accused product does not literally satisfy a claim limitation but performs substantially the same function in substantially the same way to achieve substantially the same result. Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605 (1950); Warner-Jenkinson, 520 U.S. 17 (1997). See doctrine of equivalents.
Domestic industry (ITC): A jurisdictional requirement under Section 337 that a domestic industry "exists or is in the process of being established" with respect to articles protected by the patent. 19 U.S.C. § 1337(a)(2)–(3). Two prongs: technical (the patentee or licensee practices at least one claim) and economic (significant U.S. investment in plant, labor, capital, or exploitation). See ITC Section 337.

E

eBay test: The four-factor test for permanent injunctions: (1) irreparable injury; (2) inadequacy of legal remedies; (3) balance of hardships; (4) public interest. eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388 (2006). The Supreme Court rejected the Federal Circuit's prior near-automatic injunction rule. See eBay v. MercExchange; permanent injunctions.
En banc: Hearing or rehearing by all active judges of the court of appeals. At the Federal Circuit, en banc review is reserved for issues of exceptional importance or to resolve intracircuit conflicts. Federal Rule of Appellate Procedure 35; Federal Circuit Rule 35.
Enablement: The requirement under 35 U.S.C. § 112(a) that the specification teach a person of ordinary skill to make and use the full scope of the claimed invention without undue experimentation. Amgen Inc. v. Sanofi, 598 U.S. 594 (2023), reinforced that broader claims demand broader enabling disclosure. See written description & enablement.
Entire market value rule (EMVR): A damages doctrine permitting use of the entire product as the royalty base only if the patented feature drives consumer demand for the entire product. LaserDynamics, Inc. v. Quanta Computer, Inc., 694 F.3d 51 (Fed. Cir. 2012). Otherwise the royalty must be apportioned to the smallest salable patent-practicing unit (SSPPU). See reasonable royalty.
Equivalents (DOE): See doctrine of equivalents. Equivalents must be assessed limitation by limitation; finding equivalence cannot eliminate a claim limitation.
Estoppel (prosecution history, IPR, assignor): Three principal patent estoppels: (1) prosecution history estoppel bars recapture, under the doctrine of equivalents, of subject matter surrendered during prosecution; (2) IPR estoppel under 35 U.S.C. § 315(e) prevents a petitioner from later asserting in district court or the ITC any ground "raised or reasonably could have raised" in IPR; (3) assignor estoppel bars an inventor-assignor from challenging validity in court.
Exceptional case: A case meriting attorneys' fees under 35 U.S.C. § 285. Octane Fitness, LLC v. ICON Health & Fitness, Inc., 572 U.S. 545 (2014), defined "exceptional" as one that stands out from others with respect to substantive strength of the litigating position or the unreasonable manner in which it was litigated. See exceptional case; Octane Fitness.
Exclusion order: An ITC remedy under 19 U.S.C. § 1337(d) directing U.S. Customs to exclude infringing articles from entry. A "limited" exclusion order applies only to named respondents; a "general" exclusion order reaches non-parties when widespread circumvention or difficulty identifying sources warrants. See ITC Section 337.
Exhaustion: Doctrine that an authorized sale of a patented article exhausts the patentee's rights to control further use or resale. Impression Products, Inc. v. Lexmark Int'l, Inc., 581 U.S. 360 (2017), held that exhaustion applies regardless of post-sale restrictions and to international sales. See patent exhaustion.
Ex parte reexamination: USPTO proceeding under 35 U.S.C. §§ 302–307 in which any party (or the Director) may request reexamination of an issued patent on the basis of patents or printed publications raising a substantial new question of patentability. Unlike IPR, the requester (if a third party) has no further role after the request. Available throughout the patent's life.
Experimental use exception: Doctrine that uses primarily for experimentation may avoid the public-use bar and on-sale bar. City of Elizabeth v. Pavement Co., 97 U.S. 126 (1877). The experimental-use exception is narrow; commercial exploitation defeats it. There is also a separate, narrower common-law experimental-use defense to infringement, which the Federal Circuit substantially limited in Madey v. Duke University, 307 F.3d 1351 (Fed. Cir. 2002).

F

False marking: Marking an unpatented article as patented with intent to deceive the public. 35 U.S.C. § 292. The AIA limited qui tam standing: only the United States or a competitor who has suffered competitive injury may sue. Marking a product with an expired patent is not actionable absent intent to deceive.
File wrapper: The complete USPTO record of a patent application, including the specification as filed, claims, Office actions, amendments, applicant arguments, and information disclosure statements. Now electronically maintained as the Image File Wrapper (IFW). The file wrapper (a/k/a prosecution history) is intrinsic evidence in claim construction. See claim construction.
FRAND: "Fair, reasonable, and non-discriminatory" — the licensing commitment a standard-setting organization typically requires from members holding standard-essential patents. FRAND obligations have been enforced as contracts with the SSO, with implementers as third-party beneficiaries. Microsoft Corp. v. Motorola, Inc., 795 F.3d 1024 (9th Cir. 2015); Ericsson, Inc. v. D-Link Sys., Inc., 773 F.3d 1201 (Fed. Cir. 2014).
Foreseeability (Festo): Doctrine governing prosecution-history estoppel: a narrowing amendment for reasons of patentability creates a presumption of estoppel that the patentee can rebut by showing, among other things, that the alleged equivalent was unforeseeable at the time of the amendment. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002). See prosecution history estoppel.
Federal Circuit: See CAFC; Federal Circuit.
Final written decision (FWD): The PTAB's merits decision in an IPR or PGR, which must issue within one year of institution (extendable by six months for good cause). 35 U.S.C. §§ 316(a)(11), 326(a)(11). Triggers IPR estoppel under § 315(e). The FWD is appealable to the Federal Circuit.

G

Georgia-Pacific factors: The fifteen factors set out in Georgia-Pacific Corp. v. United States Plywood Corp., 318 F. Supp. 1116 (S.D.N.Y. 1970), used to construct a hypothetical negotiation for a reasonable royalty. The factors include established royalties, comparable licenses, the nature and scope of the license, the patentee's licensing policy, and the utility of the patented technology over alternatives. See reasonable royalty.
Graham factors: The four-part framework for obviousness from Graham v. John Deere Co., 383 U.S. 1 (1966): (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill in the art; and (4) secondary considerations of non-obviousness. See obviousness.
General exclusion order: An ITC remedy under 19 U.S.C. § 1337(d)(2) directing exclusion of all articles infringing the patent regardless of source. Available where necessary to prevent circumvention or where there is a pattern of violation and difficulty identifying sources. See ITC Section 337.

H

Hatch-Waxman: The Drug Price Competition and Patent Term Restoration Act of 1984, codified principally at 21 U.S.C. § 355(j) and 35 U.S.C. § 271(e). Establishes the ANDA pathway for generic drugs, the artificial act of infringement under § 271(e)(2), the 30-month stay, and patent-term restoration. Litigation over Paragraph IV certifications constitutes a substantial portion of the District of Delaware's docket.
Hypothetical negotiation: The legal fiction at the core of the reasonable-royalty calculation: a negotiation between the patentee and the infringer, on the eve of first infringement, with both parties willing and assuming the patent is valid and infringed. The Georgia-Pacific factors structure the inquiry. See reasonable royalty.

I

Implied license: A non-express authorization to practice a patent, arising from conduct, equitable estoppel, or legal estoppel. Sale of a non-staple component with no reasonable non-infringing use can convey an implied license to use the patented combination. Met-Coil Sys. Corp. v. Korners Unlimited, Inc., 803 F.2d 684 (Fed. Cir. 1986).
Importation: An act of infringement under 35 U.S.C. § 271(a). The ITC has parallel jurisdiction over imported infringing articles under Section 337, 19 U.S.C. § 1337. Importation of a product made abroad by a process patented in the U.S. is also infringement under § 271(g).
Indirect infringement: Liability for actively inducing or contributing to infringement by another. 35 U.S.C. § 271(b)–(c). Indirect infringement requires an underlying act of direct infringement and the requisite knowledge. See indirect infringement.
Induced infringement: Active inducement under 35 U.S.C. § 271(b). Requires (1) an act of direct infringement and (2) the inducer's knowledge of the patent and of the infringing nature of the induced acts. Global-Tech Appliances, Inc. v. SEB S.A., 563 U.S. 754 (2011) (willful blindness suffices); Commil USA, LLC v. Cisco Sys., Inc., 575 U.S. 632 (2015) (good-faith belief of invalidity is no defense).
Inequitable conduct: An equitable defense rendering a patent unenforceable, requiring proof by clear and convincing evidence of (1) materiality and (2) specific intent to deceive the USPTO. Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (en banc), tightened both elements: but-for materiality and a specific intent that is the single most reasonable inference. See inequitable conduct.
Inherency: Doctrine in anticipation analysis: a prior-art reference may anticipate a claim limitation not expressly disclosed if the limitation is necessarily present. The party asserting inherency must show that the missing element is necessarily, not merely probably or possibly, present. Continental Can Co. v. Monsanto Co., 948 F.2d 1264 (Fed. Cir. 1991). See anticipation.
Injunction (preliminary, permanent): Equitable relief restraining infringement. Preliminary injunctions require likelihood of success, irreparable harm, balance of hardships, and public interest. Permanent injunctions are governed by the four-factor eBay test. 35 U.S.C. § 283. See permanent injunctions.
Inter partes reexamination (sunset 2012): The third-party reexamination procedure under former 35 U.S.C. §§ 311–318 (pre-AIA), which allowed a third-party requester to participate in USPTO reexamination. Replaced by IPR effective September 16, 2012. Pending inter partes reexaminations were grandfathered to completion.
Inter partes review (IPR): Post-grant administrative trial before the PTAB under 35 U.S.C. §§ 311–319, available nine months after issuance (or after termination of any PGR). Grounds limited to anticipation and obviousness based on patents and printed publications. Standard: reasonable likelihood that petitioner would prevail as to at least one claim. See IPR.
Invalidity contentions: Local-patent-rule disclosures identifying the prior art relied on for invalidity, the grounds (anticipation, obviousness, § 112), and claim charts mapping references to limitations. EDTX P.R. 3-3, NDCA Patent L.R. 3-3, and similar rules in other districts impose deadlines and content requirements.
Inventor: The individual or individuals who conceived the claimed invention. 35 U.S.C. § 100(f). Joint inventors need not contribute equally or to every claim, but each must contribute to the conception of at least one claim. Pannu v. Iolab Corp., 155 F.3d 1344 (Fed. Cir. 1998). Misjoinder or non-joinder may be corrected under 35 U.S.C. § 256.
ITC: The United States International Trade Commission, an independent agency that adjudicates Section 337 unfair-import investigations, including patent-based complaints. ITC remedies are limited to exclusion orders and cease-and-desist orders; the ITC cannot award damages. See ITC Section 337.

J

Joint infringement: Liability for direct infringement under § 271(a) when multiple actors collectively perform all steps of a method claim. After Akamai Techs., Inc. v. Limelight Networks, Inc., 797 F.3d 1020 (Fed. Cir. 2015) (en banc), one party can be liable for the acts of another where the first directs or controls the second's performance, including by conditioning a benefit on performance.
Judgment as a matter of law (JMOL): Federal Rule of Civil Procedure 50. Granted when no reasonable jury could find for the nonmoving party. Patent JMOL motions are common on infringement, invalidity, willfulness, and damages. The Federal Circuit reviews JMOL rulings under regional-circuit law on procedural standards but applies its own law on substantive patent issues.
Jury (Seventh Amendment): The Seventh Amendment guarantees jury trial in patent infringement actions seeking legal relief (damages). Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996), held that claim construction is for the court, not the jury, despite the right to a jury on infringement. Equitable issues (inequitable conduct, exceptional case, injunction) are tried to the bench.

K

Kingsdown: Kingsdown Medical Consultants, Ltd. v. Hollister Inc., 863 F.2d 867 (Fed. Cir. 1988) (en banc). Established that gross negligence is insufficient to support inequitable conduct: specific intent to deceive must be shown. Refined and tightened in Therasense. See inequitable conduct.
KSR: KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007). The Supreme Court rejected the Federal Circuit's rigid "teaching, suggestion, or motivation" test as the sole obviousness inquiry, restoring a flexible Graham analysis informed by common sense. See KSR v. Teleflex; obviousness.
Knowledge (for indirect infringement): The mental-state element required for induced and contributory infringement: knowledge of the patent and knowledge that the induced acts constitute infringement. Global-Tech Appliances, Inc. v. SEB S.A., 563 U.S. 754 (2011). Willful blindness, but not mere negligence, satisfies the standard.

L

Laches (no longer available — SCA Hygiene): Equitable defense formerly barring damages for unreasonable, prejudicial delay in filing suit. The Supreme Court in SCA Hygiene Products Aktiebolag v. First Quality Baby Products, LLC, 580 U.S. 328 (2017), held laches unavailable as a defense to damages within the § 286 six-year limitations period. Equitable estoppel remains available.
Licensee standing: An exclusive licensee with all substantial rights may sue alone in its own name. A licensee with fewer than all substantial rights must join the patentee. A bare (non-exclusive) licensee lacks Article III standing to sue. See standing; Lone Star Silicon Innovations LLC v. Nanya Tech. Corp., 925 F.3d 1225 (Fed. Cir. 2019).
Limitation: An element or recitation of a patent claim. The all-elements rule requires that every limitation be present in the accused product, literally or equivalently, for infringement. Limitations are construed as a matter of law. See claim construction.
Lone Star: Lone Star Silicon Innovations LLC v. Nanya Technology Corp., 925 F.3d 1225 (Fed. Cir. 2019). Held that a plaintiff lacking all substantial rights to a patent does not have constitutional standing on its own and that joinder of the patent owner is required. Frequently cited in motions to dismiss patent-licensing-entity suits. See standing.

M

Markman hearing: A pretrial hearing at which the district court hears argument and (sometimes) evidence on disputed claim terms before issuing a claim-construction order. Required by Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996), and shaped by Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc). See Markman hearings.
Marking statute (§ 287): 35 U.S.C. § 287(a) conditions pre-suit damages on either marking patented articles or providing actual notice to the infringer. Failure to mark limits damages to the period after actual notice. The patentee bears the burden to show compliance once the alleged infringer identifies products that should have been marked. Arctic Cat Inc. v. Bombardier Recreational Prods. Inc., 950 F.3d 860 (Fed. Cir. 2020).
Mayo framework: The two-step test for § 101 eligibility from Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66 (2012), extended to abstract ideas in Alice Corp. v. CLS Bank Int'l, 573 U.S. 208 (2014). Step 1: is the claim directed to a judicial exception? Step 2: do the additional elements amount to "significantly more"? See § 101 eligibility; Alice v. CLS Bank.
Mandamus: An extraordinary writ under 28 U.S.C. § 1651. The Federal Circuit grants mandamus on transfer-of-venue rulings only for clear abuse of discretion, but has done so frequently in EDTX/WDTX cases. In re TS Tech USA Corp., 551 F.3d 1315 (Fed. Cir. 2008); In re Apple Inc., 979 F.3d 1332 (Fed. Cir. 2020).
Means-plus-function: Claim format under 35 U.S.C. § 112(f) reciting a function performed by a means or step. Construction is limited to the corresponding structure, material, or acts disclosed in the specification (and equivalents thereof). Failure to disclose corresponding structure renders the claim indefinite. Williamson v. Citrix Online, LLC, 792 F.3d 1339 (Fed. Cir. 2015) (en banc).
MedImmune: MedImmune, Inc. v. Genentech, Inc., 549 U.S. 118 (2007). Held that a licensee in good standing may bring a declaratory-judgment action challenging the licensed patent without breaching or repudiating the license. Lowered the threshold for DJ jurisdiction.
Microsoft v. i4i (clear and convincing for invalidity): Microsoft Corp. v. i4i Ltd. Partnership, 564 U.S. 91 (2011). Held that an invalidity defense in district court must be proved by clear and convincing evidence, regardless of whether the prior art was before the examiner. The PTAB applies a preponderance standard in IPR.

N

Nautilus: Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014). Replaced the Federal Circuit's "insolubly ambiguous" indefiniteness standard with the "reasonable certainty" test: a claim must inform a person skilled in the art about the scope of the invention with reasonable certainty. See definiteness.
Non-obviousness: The statutory requirement under 35 U.S.C. § 103 that the differences between the claimed invention and the prior art not have been obvious to a person of ordinary skill in the art at the time of the invention (pre-AIA) or as of the effective filing date (AIA). Analyzed under the Graham factors. See obviousness.
Non-practicing entity (NPE): A patent owner that does not itself make or sell products embodying the patent. Often used pejoratively ("patent troll"), the term encompasses universities, research institutes, individual inventors, and licensing entities. NPE status can affect the eBay irreparable-harm analysis and venue strategy.
Notice (actual / constructive): Under § 287, "constructive notice" is given by marking patented articles; "actual notice" is achieved by an affirmative communication identifying the patent and specific accused activities. Notice triggers the start of recoverable damages where the patentee or its licensees sell unmarked patented articles. Amsted Indus. Inc. v. Buckeye Steel Castings Co., 24 F.3d 178 (Fed. Cir. 1994).

O

Obviousness: See non-obviousness; obviousness; KSR v. Teleflex.
Obviousness-type double patenting: Judicially created doctrine barring claims that are not patentably distinct from claims of an earlier-issued, commonly owned patent. Cured by a terminal disclaimer tying the later patent's term to the earlier and requiring common ownership. In re Longi, 759 F.2d 887 (Fed. Cir. 1985).
Offer to sell: An act of infringement under 35 U.S.C. § 271(a). The offer must contemplate sale within the United States. Halo Elecs., Inc. v. Pulse Elecs., Inc., 769 F.3d 1371 (Fed. Cir. 2014). The offer is judged by traditional contract principles.
On-sale bar: Pre-AIA § 102(b) and AIA § 102(a)(1) bar a patent on an invention "on sale" more than one year before the U.S. filing (pre-AIA) or before the effective filing date (AIA). The Supreme Court in Helsinn Healthcare S.A. v. Teva Pharmaceuticals USA, Inc., 586 U.S. 123 (2019), held that confidential sales can trigger the AIA on-sale bar. See on-sale bar.
Opinion of counsel: Written analysis from patent counsel concluding that an accused product does not infringe or that the patent is invalid. Once central to non-willfulness defenses, opinions are now one factor of many under Halo v. Pulse. 35 U.S.C. § 298 provides that failure to obtain or present advice of counsel cannot be used to prove willfulness or inducement.
Ordinary skill in the art (POSITA): The hypothetical "person having ordinary skill in the art" — the legal lens through which obviousness, enablement, written description, and claim construction are evaluated. The POSITA's level of skill is a Graham factor and is established by expert testimony based on factors including the educational level of active workers, the type of problems encountered, and the sophistication of the technology.

P

Parent application: An earlier-filed application from which a continuation, divisional, or continuation-in-part claims priority benefit under 35 U.S.C. § 120 (or § 119 for foreign priority). The progeny inherit the parent's filing date for subject matter common to both.
Patent agent: A non-attorney registered to practice before the USPTO upon passing the patent bar. Patent agents may prosecute applications and represent inventors before the Office but cannot represent clients in court. Communications with patent agents on USPTO matters are protected by an analogous privilege. In re Queen's University at Kingston, 820 F.3d 1287 (Fed. Cir. 2016).
Patent attorney: A licensed attorney also registered to practice before the USPTO. Patent attorneys can prosecute applications, render opinions, and litigate in court.
Patent exhaustion: See exhaustion; patent exhaustion.
Patent misuse: An equitable defense rendering a patent unenforceable while the misuse persists. Misuse traditionally turned on impermissible expansion of the patent grant (e.g., tying, post-expiration royalties). Significantly narrowed by 35 U.S.C. § 271(d) and by antitrust principles. Princo Corp. v. ITC, 616 F.3d 1318 (Fed. Cir. 2010) (en banc).
Phillips v. AWH: Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc). Established the modern hierarchy of claim-construction sources: claims, specification, and prosecution history (intrinsic evidence), with extrinsic evidence (dictionaries, expert testimony) playing a secondary role. See Phillips v. AWH.
Post-grant review (PGR): AIA proceeding under 35 U.S.C. §§ 321–329 available within nine months of issuance for AIA-eligible patents. Grounds include any § 282(b)(2)–(3) defense, including § 101 and § 112 — broader than IPR. Threshold: more likely than not that at least one challenged claim is unpatentable. See PGR.
Prior art: The body of public knowledge against which novelty and non-obviousness are tested. Defined by 35 U.S.C. § 102. Pre-AIA § 102 included date-based and act-based categories (e.g., known or used by others, on sale, public use). The AIA simplified the universe to printed publications, public uses, sales, and other public availability before the effective filing date.
Prosecution history estoppel: Doctrine that surrender of subject matter during prosecution — by amendment for reasons of patentability or by argument — bars recapture under the doctrine of equivalents. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002). See prosecution history estoppel.
Provisional application: A streamlined application under 35 U.S.C. § 111(b) that establishes a filing date but is never examined and automatically expires after 12 months. A non-provisional must be filed within that period to claim benefit. Provisionals must satisfy § 112(a) for the subject matter relied on.
Public use: Pre-AIA § 102(b) and AIA § 102(a)(1) bar a patent where the invention was "in public use" before the critical date. Egbert v. Lippmann, 104 U.S. 333 (1881). Even a single, non-confidential use can trigger the bar. See public-use bar.
PTAB: The Patent Trial and Appeal Board, the USPTO's adjudicatory body, established by the AIA in place of the Board of Patent Appeals and Interferences. Hears ex parte appeals from examination, IPRs, PGRs, and (until 2020) CBM reviews. See PTAB; PTAB procedure.

Q

Quanta: Quanta Computer, Inc. v. LG Electronics, Inc., 553 U.S. 617 (2008). Held that the authorized sale of a component that substantially embodies a patented method exhausts the patentee's rights in the method. Reinforced by Impression Products v. Lexmark. See patent exhaustion.

R

Reasonable royalty: The statutory floor for damages under 35 U.S.C. § 284 — "in no event less than a reasonable royalty for the use made of the invention by the infringer." Calculated principally through a hypothetical-negotiation framework structured by the Georgia-Pacific factors. See reasonable royalty.
Reduction to practice: The completion of an embodiment of the invention that works for its intended purpose. Actual reduction to practice requires construction and testing; constructive reduction to practice occurs when a sufficient patent application is filed. Under pre-AIA law, important for priority; under the AIA, less so given the first-inventor-to-file rule.
Reexamination: USPTO review of an issued patent on the basis of patents and printed publications raising a substantial new question of patentability. Currently available only as ex parte reexamination under 35 U.S.C. §§ 302–307. Inter partes reexamination was replaced by IPR in 2012.
Regular and established place of business: The second prong of the patent venue statute, 28 U.S.C. § 1400(b). After TC Heartland, the Federal Circuit clarified the requirements: (1) a physical place in the district; (2) a regular and established place; (3) the place must be the defendant's. In re Cray Inc., 871 F.3d 1355 (Fed. Cir. 2017). See patent venue.
Reissue: Procedure under 35 U.S.C. § 251 to correct an issued patent that is wholly or partly inoperative or invalid by reason of a defective specification, drawing, or claiming more or less than the patentee had a right to claim. Broadening reissues must be filed within two years of issuance. The recapture rule limits broadening reissues that recapture surrendered subject matter.
Restriction requirement: An examiner's requirement under 35 U.S.C. § 121 that an applicant elect among independent and distinct inventions claimed in a single application. The non-elected claims may be pursued in a divisional, which is shielded from § 121 double-patenting attacks based on the parent.
Rite-Hite: Rite-Hite Corp. v. Kelley Co., 56 F.3d 1538 (Fed. Cir. 1995) (en banc). Allowed lost-profits damages for sales of unpatented products that competed with the infringing product, where the lost sales were reasonably foreseeable. The decision broadened lost-profits recovery beyond strict embodiment of the patent.
Royalty base: The unit and revenue figure to which the royalty rate is applied. The royalty base is constrained by the apportionment requirement: it must reflect only the value of the patented technology, ordinarily the smallest salable patent-practicing unit unless the EMVR applies. VirnetX, Inc. v. Cisco Sys., Inc., 767 F.3d 1308 (Fed. Cir. 2014).

S

SAS Institute: SAS Institute Inc. v. Iancu, 584 U.S. 357 (2018). Held that when the PTAB institutes IPR on a petition, it must address every claim challenged in the petition — there is no partial institution. Effectively eliminated the prior practice of instituting only on some claims and grounds.
Section 101 / 102 / 103 / 112 / 271 / 281 / 284 / 285 / 287 / 298: The principal Title 35 sections in litigation: § 101 (subject-matter eligibility), § 102 (novelty), § 103 (non-obviousness), § 112 (specification, definiteness, means-plus-function), § 271 (infringement, all subsections including (a) direct, (b) induced, (c) contributory, (e) Hatch-Waxman, (f) supplying components abroad, (g) imported products of patented processes), § 281 (civil action), § 284 (damages), § 285 (attorneys' fees), § 287 (marking), § 298 (advice of counsel). See the Title 35 reference.
Secondary considerations: The fourth Graham factor in the obviousness inquiry: objective indicia including commercial success, long-felt but unsolved need, failure of others, copying, industry praise, licensing, and skepticism. The patentee must show a nexus between the indicia and the claimed invention. Demaco Corp. v. F. Von Langsdorff Licensing Ltd., 851 F.2d 1387 (Fed. Cir. 1988).
Separately patentable: The standard for distinctness in restriction practice and in obviousness-type double patenting. Two inventions or claims are "separately patentable" if neither anticipates nor renders obvious the other.
Single-actor rule: Pre-Akamai rule that direct infringement of a method claim required a single actor to perform every step. After Akamai Techs., Inc. v. Limelight Networks, Inc., 797 F.3d 1020 (Fed. Cir. 2015) (en banc), liability extends to one party where it directs or controls another's performance, including by conditioning a benefit on participation.
Smallest salable patent-practicing unit (SSPPU): An apportionment doctrine: where a multi-component product practices the patent through one component, the royalty base should ordinarily be the smallest salable component that practices the patent, unless the EMVR is satisfied. VirnetX, Inc. v. Cisco Sys., Inc., 767 F.3d 1308 (Fed. Cir. 2014). See reasonable royalty.
Specification: The portion of the patent that describes the invention. Must satisfy the written-description, enablement, and (pre-AIA) best-mode requirements of 35 U.S.C. § 112(a). The specification is "the single best guide to the meaning of a disputed term." Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc).
Standing: Constitutional and prudential requirements for bringing suit. In patent cases, the patentee or an exclusive licensee with all substantial rights has standing. See standing.
Summary judgment: Federal Rule of Civil Procedure 56. Granted where there is no genuine dispute of material fact and the movant is entitled to judgment as a matter of law. Common in patent cases on issues of claim construction (sometimes), § 101 eligibility, and non-infringement; less common on invalidity given the clear-and-convincing burden.

T

TC Heartland: TC Heartland LLC v. Kraft Foods Group Brands LLC, 581 U.S. 258 (2017). Held that for purposes of patent venue under 28 U.S.C. § 1400(b), a domestic corporation "resides" only in its state of incorporation. Reversed three decades of Federal Circuit practice and reshaped patent venue. See TC Heartland; patent venue.
Technical prong (ITC): The element of the ITC domestic-industry requirement that requires the complainant or its licensees to practice at least one valid claim of the asserted patent. Compared to the economic prong, which addresses U.S. investment. See ITC Section 337.
Terminal disclaimer: A statement under 35 U.S.C. § 253(b) that disclaims the terminal portion of a patent's term to align it with an earlier commonly owned patent's expiration. Commonly used to overcome obviousness-type double-patenting rejections; ties enforceability to common ownership.
Therasense: Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (en banc). Tightened both prongs of inequitable conduct: but-for materiality (subject to a narrow affirmative-egregious-misconduct exception) and specific intent that is the single most reasonable inference from the evidence. See inequitable conduct.
Tracker order (E.D. Tex.): An EDTX scheduling tool issued early in patent cases that sets fixed dates for infringement contentions, invalidity contentions, claim construction, and trial. Reflects the EDTX practice of rapid, predictable case progression. See Eastern District of Texas.
Trade dress: Trademark protection for non-functional design features that serve as source identifiers. Distinct from design patents, which protect ornamental features for a fixed term. Trade dress and design patents can sometimes coexist on the same product feature where requirements are satisfied.
Transfer of venue (§ 1404): 28 U.S.C. § 1404(a) authorizes transfer to "any other district where it might have been brought" for the convenience of parties and witnesses, in the interest of justice. Reviewed for abuse of discretion; the Federal Circuit has granted mandamus on transfer rulings repeatedly in EDTX/WDTX patent cases. In re Volkswagen of America, Inc., 545 F.3d 304 (5th Cir. 2008) (en banc).

U

USPTO: The United States Patent and Trademark Office, the agency within the Department of Commerce that examines and issues patents and registers trademarks. Headed by the Director, who also presides over the PTAB by statute. 35 U.S.C. § 6.
Unenforceability: An equitable status — distinct from invalidity — in which a patent cannot be enforced despite remaining nominally valid. The principal grounds are inequitable conduct, patent misuse, and equitable estoppel. Unenforceability for inequitable conduct extends to all claims of the patent, regardless of whether they relate to the misconduct.
Utility patent: The standard "patent for any new and useful process, machine, manufacture, or composition of matter" under 35 U.S.C. § 101. Term is generally 20 years from the earliest non-provisional U.S. filing date. Distinct from design patents (§ 171) and plant patents (§ 161).

V

Validity (presumption): An issued patent is presumed valid under 35 U.S.C. § 282(a). The presumption is overcome only by clear and convincing evidence. Microsoft Corp. v. i4i Ltd. Partnership, 564 U.S. 91 (2011). The presumption does not apply in IPR or PGR, where the standard is preponderance of the evidence.
Venue (§ 1400(b)): The patent venue statute, 28 U.S.C. § 1400(b): suit may be brought in (1) the judicial district where the defendant resides, or (2) where the defendant has committed acts of infringement and has a regular and established place of business. TC Heartland confirmed that "resides" means state of incorporation for domestic corporations. See patent venue.
Vitiation: A limitation on the doctrine of equivalents: an equivalent that would effectively read a claim limitation out of the claim "vitiates" the limitation and is impermissible. Vitiation is treated as a legal determination about whether a reasonable jury could find equivalence given the all-elements rule. Deere & Co. v. Bush Hog, LLC, 703 F.3d 1349 (Fed. Cir. 2012).

W

Wands factors: The eight factors used to evaluate enablement under 35 U.S.C. § 112(a): (1) quantity of experimentation needed; (2) amount of direction provided; (3) presence of working examples; (4) nature of the invention; (5) state of the prior art; (6) relative skill of those in the art; (7) predictability of the art; (8) breadth of the claims. In re Wands, 858 F.2d 731 (Fed. Cir. 1988). See written description & enablement.
Warner-Jenkinson: Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17 (1997). Reaffirmed the doctrine of equivalents but required a limitation-by-limitation analysis (the all-elements rule), and established the presumption that a narrowing amendment for unstated reasons is presumed to be for patentability — invoking prosecution history estoppel.
Willfulness: Subjective culpability supporting enhanced damages under 35 U.S.C. § 284. Halo Electronics, Inc. v. Pulse Electronics, Inc., 579 U.S. 93 (2016), discarded the prior Seagate two-part test in favor of a flexible, fact-driven inquiry into the egregiousness of the infringer's conduct. See willfulness; Halo v. Pulse.
Witness (fact, expert): Patent cases typically involve fact witnesses (inventors, prosecution counsel, engineers, sales personnel) and expert witnesses (technical, damages, sometimes industry-practice). Expert testimony is governed by Federal Rule of Evidence 702 and screened for reliability under Daubert. Expert reports are due at the time fixed in the scheduling order.
Written description: The requirement under 35 U.S.C. § 112(a) that the specification reasonably convey to a person of ordinary skill that the inventor had possession of the claimed invention as of the filing date. Ariad Pharmaceuticals, Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010) (en banc). See written description & enablement.

Y

Yield (claim element): In claim drafting, a numerical or threshold yield (e.g., percentage purity, conversion rate) is treated as a claim limitation that the accused product or process must satisfy. Yield ranges raise questions of whether overlapping prior-art ranges anticipate, and whether sub-ranges are "patentably distinct" from broader genus disclosures. OSRAM Sylvania, Inc. v. American Induction Techs., Inc., 701 F.3d 698 (Fed. Cir. 2012).