December 01, 2020 WEBINAR FEATURE

The “Essence” of an Invention Is as Important as the Claims

Jerry A. Riedinger

©2020. Published in Landslide, Vol. 13, No. 2, November/December 2020, by the American Bar Association. Reproduced with permission. All rights reserved. This information or any portion thereof may not be copied or disseminated in any form or by any means or stored in an electronic database or retrieval system without the express written consent of the American Bar Association or the copyright holder.

“It is a bedrock principle of patent law,” says the Federal Circuit Court of Appeals, that “the claims of a patent define the invention.”1 And the U.S. Supreme Court agrees: “the claims made in the patent are the sole measure of the grant.”2 In the words of Judge Giles Rich, an author of the U.S. Patent Act of 1952, “the name of the game is the claim.”3

But it is not so. Time and again, district courts, the Federal Circuit, and even the Supreme Court have disregarded claim language in favor of a concept variously termed the “essence,” “gist,” “heart,” or “thrust” of the invention; the “essential features” of the invention; or a patent’s “inventive concept.” All such terms refer to a fundamental notion: a patent has at least one central idea representing the patent’s core advancement. Saying “there is no legally recognizable or protected ‘essential’ element, ‘gist’ or ‘heart’ of the invention”4 thus obscures the reality that the “essence” of the invention permeates the patent world. Indeed, evaluating a patent’s essence or “inventive contribution” is not merely common, but sometimes required by the law. Understanding the role of a patent’s “essence” is therefore indispensable for effective patent practice, whether as a litigator, prosecutor, or advisor.

The Heart of Patentable Subject Matter

Abridging the claims is central to modern patentable subject matter analysis. Virtually all patent practitioners have firsthand experience with the revolution created by Mayo5 and Alice6 and the wreckage of issued patents resulting from those cases. That destruction means virtually every defendant will include a § 101 review in their initial case analysis, and virtually every patent prosecutor will consider patentable subject matter questions in planning an application. Each such analysis requires disregard of much of the language and features of a patent’s claims, and focusing on their crux.

The foundation of modern § 101 law is a court’s ability to reduce claims to a shorthand description of an underlying abstract “concept.” Hence, every § 101 review begins not by looking at a claim’s elements, but by distilling a patent’s entire set of claims into their “heart”7: a truncated phrase that removes nearly all claim features, leaving a residue bearing little resemblance to the language chosen by the patent drafter. The Federal Circuit thus looks at “their character as a whole” when reviewing the claims for § 101 compliance.8 The patent is then probed for an “inventive concept,” indeed, a “transformative” inventive concept,9 in only partial consideration of claim elements—the Federal Circuit requires the “abstract concept” and “inventive concept” to be separate, and mandates unpatentability if an “inventive concept” is found solely in the claims’ “abstract concept.”10

This approach undermines decades of anticipation and obviousness law founded on consideration of every claim element.11 Indeed, § 101 is a shortcut that allows patents lacking an inventive concept to be invalidated at the pleading stage, often without any claim construction determining the meaning—or importance—of individual claim elements. The core of that process is the ability to ignore the plethora of terms, phrases, and other limitations in the claims by recasting the claims as “directed to” an abstract idea. Once the baggage of multiple limitations is cast aside and the claims are reduced to a suitably simple idea, little effort is required to declare an absence of an inventive concept, a result that is achieved with far less effort than if every claim limitation were considered.

And not just individual claim limitations are ignored. Section 101 law allows a single claim to be “representative” of every other claim in a patent, in disregard of the long-standing principle that different claims have separate meanings.12 Should the representative claim be found to lack an inventive concept, that deficiency may then invalidate all other disputed claims. And should a method claim be deemed representative and found deficient under § 101, even supposedly represented product claims may be invalidated.13 Claims are not just secondary in § 101 law, but often irrelevant. Any § 101 analysis failing to focus on the advance, i.e., the inventive contribution, will be deficient.

The Gist of Patent Exhaustion

Section 101 cases are far from the sole example of courts studiously disregarding claim language. The Supreme Court’s 1942 Univis14 decision analyzed alleged antitrust violations by evaluating whether a product “embodied the essential features” of a patent. When Univis was embraced more recently in Quanta,15 the Supreme Court proclaimed exhaustion of patent rights through sale of a product that could not infringe the patent, but which again “embodied the essential features” of the patent. The protection sought by crafting details into claims can thereby be vitiated by sale of a product having less than all the carefully selected elements. Understanding potential exhaustion thus requires determining what features are essential—in disregard of the “all elements rule”16—and how those features can be substantially “embodied” in a product lacking some of the claimed elements. While the Supreme Court’s explanation of exhaustion has been less than Delphic, the “essential features” of a patent are nevertheless a form of the “gist” of the invention, making detection of a patent’s essence a critical skill. Only then can exhaustion be accurately predicted or avoided.

The Heart of the Federal Circuit

Despite expressly and repeatedly condemning the “essence,” “gist,” and “heart” of the invention, the Federal Circuit has used those exact terms in multiple decisions throughout its existence.17 The phrases were used to analyze wide-ranging subjects, including obviousness,18 claim construction,19 preamble interpretation,20 and various validity-related topics.21 The court in each case found the condensed phrase useful to explain its reasoning. Even Chief Judge Markey, a staunch opponent of the “gist” of an invention, stated that review of “the ‘gist’ or ‘essence’ of the invention may be appropriate,” at least to determine priority of invention.22 The U.S. Patent and Trademark Office’s use of the “essence” of the invention in the MPEP23 supports such decisions, and the Supreme Court may have spurred an acceleration of such cases when it found the “heart” of the invention a useful concept in Markman.24

Federal Circuit decisions are similarly replete with references to a single claim being “illustrative” of an issue.25 While a convenient way to avoid potentially duplicative discussions in an opinion (especially in nonprecedential decisions), the approach nevertheless generalizes claims and shows minimal deference to independent evaluation of each claim’s separate elements. An analogous result occurs when the Federal Circuit gives no weight to “whereby” clauses that simply express an intended result26—language selected by the claim drafter is then disregarded.

The Federal Circuit thus embraces the heart of an invention in lieu of the precise claim language despite its frequent condemnation of the practice.

The Essence of Infringement

Infringement analyses theoretically rely on the all elements rule and normally reject a concentration on the essence of the invention. Yet infringement is another topic where the Federal Circuit has referred to the “gist” of the invention.27 Moreover, a claim’s “essence” or “gist” often underlies the Federal Circuit’s doctrine of equivalents analysis.28 Although reduced in modern patent cases to features that are only insubstantially different from an expressly claimed element, the doctrine of equivalents is a close cousin to evaluating the essence of an invention, because meticulously selected claim language can be ignored. As Chief Judge Markey stated: “consideration of the ‘essence,’ ‘gist,’ or ‘heart’ of the invention may be helpful in determining infringement under the doctrine of equivalents,” because such language is “shorthand” for the more formal doctrine of equivalents analysis.29 Similarly, the much-maligned but still valid reverse doctrine of equivalents focuses on whether a device is “so far changed in principle” from a patented article that it does not infringe despite literally falling within the claims.30 The doctrine thus looks at the “fair scope” of the patentee’s invention,31 a concept akin to the essence of the invention.

The Point of Novelty in Means-Plus-Function Claims

The “point of novelty” approach to patent analysis is similar to looking at the essence of an invention, and thus has often been criticized.32 Yet the concept retains vitality, at least because it is the foundation for the 1952 Patent Act’s allowance of means-plus-function claiming under § 112(f). That section’s predecessor was a response to the Supreme Court’s 1946 rejection of broad functional language in Halliburton,33 when a patentee used functional language “at the exact point of novelty.” The point-of-novelty approach to § 112(f) retains validity today, having been adopted by the Federal Circuit to uphold claim indefiniteness.34

The Gist of Interferences

Although a dying procedure, patent interferences are an important ancestor of the modern “gist” practices. The Supreme Court ruled long ago that the “key” to determining whether an interference disclosure supports a claim is whether the disclosure will “teach the gist of the invention.”35 Literally hundreds of interferences considered the gist of the invention, and that approach remains the law today. Interference law thus established, at least seven decades ago, that the gist of an invention is a legitimate concept in patent law.

The Consequence: Find the Inventive Contribution

The persistent use of “inventive concepts” and the “essence of the invention” in patent law does not occur because the Supreme Court and Federal Circuit are confused or misguided. Instead, the concepts are embraced because they are useful and aid courts in understanding and explaining complex issues. A focus on an invention’s essence helps clear the obscuring fog of convoluted claim language, allowing easier penetration to the heart of an issue. The inventive contribution underlying a patent is the lubricant smoothing the complicating frictions in the patent system. All practitioners should accordingly disregard attempts to reject the essence of the invention36 and instead embrace the concept.

That does not mean that claims should be disregarded. Patent drafters must write claims, opinions must consider and discuss them, post-grant challenges and Markman proceedings will focus on the claims, courts must concentrate on claims, and claims will always be at the core of trials. But practitioners must keep the big picture in mind, and the nucleus of that picture is a patent’s inventive contribution. Understanding that foundation allows selection of the best infringement theories, the best defenses, and the best grounds to assert and defend against all manner of invalidity contentions.

What, then, is the “inventive contribution”? It is the patent’s advance over the art, expressed in a simple, shorthand phrase. Just as § 101 law looks to the “focus” of a patent to determine whether it is directed to an abstract concept, the inventive contribution is derived by identifying the inventor’s development, as described in the specification, and comparing it to the prior art. The resulting inventive contribution will be a condensed description, not a detailed catalog of the development’s features. An inventive contribution is the “essence” of an invention, rather than the minutia in the specification, and its usefulness lies in its simple focus on the patent’s crux. An inventive contribution’s value derives from its precise encapsulation of the patent’s big picture, which separates the wheat from the chaff. It is the patent in a nutshell. For some inventions, e.g., new efficacious drugs, the inventive contribution will be immediately apparent, but for others, discerning the inventive contribution will require careful digging, analysis, and consultation with experts and co-counsel. The effort will be worthwhile regardless.

Using the “Inventive Contribution”

Patent drafters should thus determine the inventive contribution early in the drafting process. They should literally write a one- or two-sentence description of the contribution made by the inventors over the art, and then discuss that description with the inventors. Sometimes a single development will have more than one inventive contribution. That too is crucial information, because it will define the minimum description needed in the specification, and help inform whether multiple applications should be filed. The inventive contributions should then be the centerpiece of an application’s independent claims, with the contributions described using multiple claim formats. The specification must clearly describe all inventive contributions, using language that will illuminate the significance of every such contribution not only to the patent office, but also to the judge and jury if litigated, and to the marketplace. Naturally, the inventive contributions must be compared to the abstract ideas declared unpatentable by the Federal Circuit to ensure that such ideas are not claimed. Following that process greatly increases the value of any eventual patent.

A similar process should be followed by opinion drafters. Analysis of any patent should commence with an attempt to identify the inventive contribution. Its presence or absence is then a key indicator of the patent’s potential breadth, validity, and value. Patents lacking an inventive contribution are vulnerable in litigation and post-grant proceedings. Noninfringement opinions similarly should begin with comparison of the inventive contribution to the potentially infringing product or process. Differences from the inventive contribution are then a powerful indicator that strong noninfringement defenses exist. Those differences then become a guide to the selection of the defense’s details. And the value in a patent is directly related to the significance of the inventive contribution. Especially in litigation, the potential damages closely align with the degree of congruency between the inventive contribution and the accused product, and a more valuable inventive concept normally translates into greater potential for meaningful damage awards.

While important for prosecutors and opinion writers, determining the inventive contribution is most valuable to litigators. Arguments aligned with the inventive contribution are inherently more powerful than those created without regard to the essence of the invention. All litigators, plaintiff and defendant alike, should build their themes around the inventive contribution. Of course, a patent lacking an inventive contribution should not be asserted, and where such a contribution is present, it should only be asserted against products using that contribution. Naturally, defenses involving accused products or processes that lack the inventive contribution will focus on noninfringement, and the defenses will emphasize invalidity when patents are asserted without an inventive contribution. The inventive contribution will be the hub of any trial; indeed, after Berkheimer,37 it might be expressly contested at trial.

“Alignment” is the crucial conceptual framework for litigators. Although the inventive contribution need not be expressly described to the court, claim construction arguments aligned with the inventive contribution nevertheless have more force, because they correspond to a judge’s inherent sense of what a patent’s claims should reasonably cover. Summary judgment motions, especially those directed to noninfringement, are more powerful when nonuse of the inventive contribution is the core of the motion. Expert testimony becomes more forceful when aligned with a simply defined inventive concept. And trial themes become more powerful, starting with their expression in opening statements and ending with closing arguments, when those themes align with the inventive contribution. Indeed, once the inventive contribution is determined, the structure underlying the trial plan usually falls into place.

From start to finish, patent drafting, analysis, and litigation are all best served by recognizing that the “essence” of the invention is a friend rather than a foe. Patent practitioners should keep their eyes on the ball by focusing on the inventive contribution.


1. Innova/Pure Water, Inc. v. Safari Water Filtration Sys., Inc., 381 F.3d 1111, 1115 (Fed. Cir. 2004).

2. Aro Mfg. Co. v. Convertible Top Replacement Co., 365 U.S. 336, 339 (1961).

3. Giles S. Rich, The Extent of the Protection and Interpretation of Claims—American Perspectives, 21 Int’l Rev. Indus. Prop. & Copyright L. 497, 499 (1990).

4. Aro, 365 U.S. at 345. Some Federal Circuit cases agree. See, e.g., Allen Eng’g Corp. v. Bartell Indus., Inc., 299 F.3d 1336, 1345 (Fed. Cir. 2002) (no legally recognizable or protected essential element, gist, or heart of the invention).

5. Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66 (2012).

6. Alice Corp. Pty. Ltd. v. CLS Bank Int’l, 573 U.S. 208 (2014).

7. E.g., Athena Diagnostics, Inc. v. Mayo Collaborative Servs., LLC, 927 F.3d 1333, 1348 (Fed. Cir. 2019) (Dyk, J., concurring); Intellectual Ventures I LLC v. Erie Indem. Co., 850 F.3d 1315, 1328 (Fed. Cir. 2017).

8. Internet Patents Corp. v. Active Network, Inc., 790 F.3d 1343, 1346 (Fed. Cir. 2015). The Federal Circuit calls this the “focus” of the claims, e.g., Enfish, LLC v. Microsoft Corp., 822 F.3d 1327, 1335 (Fed. Cir. 2016), or the “basic thrust” of the asserted claims, e.g., Synopsys, Inc. v. Mentor Graphics Corp., 839 F.3d 1138, 1150 (Fed. Cir. 2016).

9. Athena Diagnostics, Inc. v. Mayo Collaborative Servs., LLC, 915 F.3d 743, 753 (Fed. Cir. 2019).

10. See Cisco Sys., Inc. v. Uniloc 2017 LLC, No. 2019-2048, slip op. at 8 (Fed. Cir. May 13, 2020).

11. E.g., Medtronic, Inc. v. Cardiac Pacemakers, Inc., 721 F.2d 1563, 1567 (Fed. Cir. 1983). But see In re Morsa, 809 F. App’x 913, 918–19 (Fed. Cir. 2020) (abstractness, novelty, and nonobviousness are separate legal and factual concepts).

12. Tandon Corp. v. U.S. Int’l Trade Comm’n, 831 F.2d 1017, 1023 (Fed. Cir. 1987) (difference in meaning and scope presumed when different words or phrases are used in separate claims).

13. E.g., Electric Power Grp., LLC v. Alstom S.A., 830 F.3d 1350, 1351 n.1 (Fed. Cir. 2016) (method claim representative of 16 claims in three patents, including system claims).

14. United States v. Univis Lens Co., 316 U.S. 241, 251 (1942).

15. Quanta Computer, Inc. v. L.G. Elecs., Inc., 553 U.S. 617, 633 (2008).

16. “It is axiomatic under our precedent that one cannot obtain patent protection for an inventive concept or for the heart or ‘essence’ of an invention . . . . [T]he limitations defining the invention tell the public what it can make, use, or sell without violating the patentee’s rights.” Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 949 (Fed. Cir. 1987) (Nies, J., additional views).

17. Terms such as the “essence” of inventions were discussed innumerable times before the Federal Circuit’s creation, and can be traced to at least the mid-19th century. See, e.g., O’Reilly v. Morse, 56 U.S. 62, 129–30, 135 (1854).

18. Arendi S.A.R.L. v. Apple Inc., 832 F.3d 1355, 1363 (Fed. Cir. 2016) (“heart”); Princeton Biochemicals, Inc. v. Beckman Coulter, Inc., 411 F.3d 1332, 1337 (Fed. Cir. 2005) (“essence”); In re Mills, 916 F.2d 680, 681 (Fed. Cir. 1990) (“essence”).

19. In re Jasinski, 508 F. App’x 950, 952 (Fed. Cir. 2013) (“essence”); Tech. Patents LLC v. T-Mobile (UK) Ltd., 700 F.3d 482, 494 (Fed. Cir. 2012) (“heart”); Seiko Epson Corp. v. Coretronic Corp., 376 F. App’x 23, 25 (Fed. Cir. 2010) (“thrust” of the patent); TiVo, Inc. v. EchoStar Commc’ns Corp., 516 F.3d 1290, 1297, 1301 (Fed. Cir. 2008) (“heart”); see also Ventana Med. Sys., Inc. v. BioGenex Labs., Inc., 473 F.3d 1173, 1185–86 (Fed. Cir. 2006) (Lourie, J., dissenting) (“essence”).

20. MEMS Tech. Berhad v. U.S. Int’l Trade Comm’n, 447 F. App’x 142, 154 (Fed. Cir. 2011) (“essence”); Vizio, Inc. v. Int’l Trade Comm’n, 605 F.3d 1330, 1340 (Fed. Cir. 2010) (“essence”); Boehringer Ingelheim Vedmedica, Inc. v. Schering-Plough Corp., 320 F.3d 1339, 1345 (Fed. Cir. 2003) (“essence”); Griffin v. Bertina, 285 F.3d 1029, 1033 (Fed. Cir. 2002) (“essence”).

21. Lexington Luminance LLC v. Inc., 601 F. App’x 963, 969 (Fed. Cir. 2015) (“essence” used in indefiniteness evaluation); MySpace, Inc. v. Graphon Corp., 672 F.3d 1250, 1257 (Fed. Cir. 2012) (“heart” used in § 102 and § 103 evaluations); Commonwealth Sci. & Indus. Research Org. v. Buffalo Tech. (USA), Inc., 542 F.3d 1363, 1381 (Fed. Cir. 2008) (“heart” used in a new matter evaluation); Musco Corp. v. Qualite, Inc., 41 U.S.P.Q.2d 1954, 1997 WL 16031, at *2 (Fed. Cir. 1997) (“essence” used in a new matter analysis); Halliburton Co. v. Schlumberger Tech. Corp., 925 F.2d 1435, 1439 (Fed. Cir. 1991) (“essence” used in inequitable conduct case); see also Critikon, Inc. v. Becton Dickinson Vascular Access, Inc., 120 F.3d 1253, 1256 (Fed. Cir. 1997) (“point of novelty” used in inequitable conduct analysis); accord McKesson Info. Sols., Inc. v. Bridge Med., Inc., 487 F.3d 897, 918 (Fed. Cir. 2007); Cargill, Inc. v. Canbra Foods, Ltd., 476 F.3d 1359, 1366 (Fed. Cir. 2007).

22. Perkin-Elmer Corp. v. Westinghouse Elec. Corp., 822 F.2d 1528, 1533 n.8 (Fed. Cir. 1987); accord Invitrogen Corp. v. Clontech Labs., Inc., 429 F.3d 1052, 1064 (Fed. Cir. 2005).

23. “The specification need not set forth details not relating to the essence of the invention.” U.S. Patent & Trademark Office, Manual of Patent Examining Procedure (MPEP) § 2165.01 (9th ed. Rev. 10.2019, June 2020) (emphasis added).

24. Markman v. Westview Instruments, Inc., 517 U.S. 370, 373 (1996).

25. E.g., Nobel Biocare Servs. AG. v. Instradent USA, Inc., 903 F.3d 1365, 1369 (Fed. Cir. 2018).

26. See Minton v. Nat’l Ass’n of Sec. Dealers, Inc., 336 F.3d 1373, 1381 (Fed. Cir. 2003).

27. E.g., Atlas Powder Co. v. E.I. Du Pont de Nemours & Co., 750 F.2d 1569, 1580 (Fed. Cir. 1984) (noting the defendants “used the gist” of the invention); Aktiebolaget Karlstads Mekaniska Werkstad v. U.S. Int’l Trade Comm’n, 705 F.2d 1565, 1569 (Fed. Cir. 1983) (describing the “gist of the invention of the claims”).

28. London v. Carson Pirie Scott & Co., 946 F.2d 1534, 1538 (Fed. Cir. 1991) (“essence”); Loctite Corp. v. Ultraseal Ltd., 781 F.2d 861, 871 (Fed. Cir. 1985) (“gist”).

29. Perkin-Elmer Corp. v. Westinghouse Elec. Corp., 822 F.2d 1528, 1533 n.8 (Fed. Cir. 1987).

30. Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 608–09 (1950).

31. Roche Palo Alto LLC v. Apotex, Inc., 531 F.3d 1372, 1377 (Fed. Cir. 2008).

32. E.g., Litton Sys., Inc., v. Whirlpool Corp., 728 F.2d 1423, 1444 (Fed. Cir. 1984).

33. Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1, 8 (1946).

34. Halliburton Energy Servs., Inc. v. M-I LLC, 514 F.3d 1244, 1255 (Fed. Cir. 2008); Clearstream Wastewater Sys., Inc. v. Hydro-Action, Inc., 206 F.3d 1440, 1446 (Fed. Cir. 2000); Tex. Instruments Inc. v. U.S. Int’l Trade Comm’n, 871 F.2d 1054, 1060 (Fed. Cir. 1989).

35. Hall v. Taylor, 332 F.2d 844, 848 (C.C.P.A. 1964).

36. See, e.g., Harold C. Wegner, First to File Patent Drafting: A Practitioner’s Guide § 9:12 (2017) (“essence” of invention is an “anachronism” and “Outdated Terminology”).

37. See Berkheimer v. HP Inc., 881 F.3d 1360, 1368 (Fed. Cir. 2018) (question of fact whether claim elements are well-understood, routine, and conventional).


Jerry A. Riedinger is a partner in the Seattle, Washington, office of Perkins Coie LLP. He has focused his practice on patent litigation since 1982 and has practiced in more than 100 different technologies.