Court Opinion

ID: 9488422
Source: CourtListenerOpinion
Date Created: 2023-08-05 12:44:51.504774+00
Date Added: 2024-06-11T17:52:53.014646
License: Public Domain

PAULINE NEWMAN, Circuit Judge,
concurring.
The doctrine of equivalents has neither greatly excited the centers of legal scholarship, nor seriously stirred action-oriented industry. Indeed, there remains a telling silence on the part of the technology community, for or against. Despite the controversial changes proposed in opinions of this court, there has been little objective policy exploration, economic analysis, legislative proposal, or even a search for consensus. There has, of course, been a good deál of speculation flowing from the inconsistency of our decisions.
The court today holds that no change is appropriate in the common law of equivalency as developed by the Supreme Court. I join in that holding, for our conclusion is in accord with precedent, and this en banc decision provides needed repose: the proposed new test of a threshold “equity” determination has been laid to rest, and the criteria of Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 70 S.Ct. 854, 94 L.Ed. 1097, 85 USPQ 328 (1950), have been reaffirmed. Indeed, any change in the legal and factual fundamentals so explicitly laid out by the Supreme Court is beyond our judicial authority. I have, however; come to doubt that the doctrine of equivalents is the best way to achieve the result for which it arose, and I encourage the technology-user community to consider whether new procedures, through the legislative process, may better serve the national interest.
Our decision, like every decision of patent principle, affects the national interest in tech-nologic innovation. I have sought to understand how that effect is manifested in the doctrine of equivalents. In so doing I have taken an analytic path not discussed by the court, albeit a path that I believe underlies the common law of equivalency. This .path has led me into the thicket of the sociology and economics of patent law, for I have attempted to place the basic question — the role and application of the doctrine of equivalents — into the practical context of the purposes and workings of the patent system, as informed by modern scholarship.
The parties and the amici curiae did not discuss this public interest aspect, although the consequences of our decision, as for all law, extend beyond those of the parties involved in the specific dispute. It is a consideration of passing complexity, for the mere availability of recourse to the doctrine of equivalents can affect technologic progress as well as commercial relationships, the core of the patent system. Thus I write to' explain my decision, and the considerations that influenced it.

Technologic Innovation and the National Interest

Technologic innovation1 has driven the American economy, over the past century, to the exclusion of virtually all other growth factors. Many students of technologic change have explained that innovative activity is fundamental to industrial vigor, developing new markets while enhancing productivity and competitiveness, thereby strengthening and enriching the nation. E.g., F.M. Scherer, Innovation and Growth (1984); Robert Solow, Technical Change and the Aggregate Production Function, 39 Rev.Econ. & Stat. 312 (1957). The role of patents in this activity is of increasing scholarly interest. E.g., David Silverstein, Patents, Science and Innovation: Historical Linkages and Implications for Global Technological Competitiveness, 17 Rutgers Computer & Tech. L.J. 261 (1991); Zvi Griliches, Patents: Recent Trends and Puzzles, in Brookings Papers on Economic Activity: Microeconomics 291 (Martin N. Baily & Clifford Winston eds., *15301989). The technology-user community has always had a practical comprehension of the value of various innovation incentives in particular commercial contexts. See Domestic Policy Review of Industrial Innovation, Department of Commerce (1979).
The doctrine of equivalents derives from the principle that an inventor should be secure in the patent rights granted by the law, even against those who manage to avoid the letter of the invention as it was described or claimed in the patent document. Early in United States patent history Justice Story stressed the superior right of the inventor as against “mere colorable alterations:”
The first question for consideration is, whether the machines used by the defendant are substantially, in their principles and mode of operation, like the plaintiffs' machines.... Mere colorable alterations of a machine are not sufficient to protect the defendant.... The material question, therefore, is not whether the same elements of motion, or the same component parts are used, but whether the given effect is produced substantially by the same mode of operation, and the same combination of powers," in both machines. Mere colorable differences, or slight improvements, cannot shake the right of the original inventor.
Odiorne v. Winkley, 18 F.Cas. 581, 582 (C.C.D.Mass.1814) (No. 10,432) (charging the jury). As in ensuing decisions, e.g., Winans v. Denmead, 56 U.S. (15 How.) 330, 343, 14 L.Ed. 717 (1854); Singer Mfg. Co. v. Cramer, 192 U.S. 265, 285-86, 24 S.Ct. 291, 299, 48 L.Ed. 437 (1904); and Sanitary Refrigerator Co. v. Winters, 280 U.S. 30, 41, 50 S.Ct. 9, 12, 74 L.Ed. 147 (1929); the trier of fact was directed to look to the substance of the invention, and ascertain whether the infringer took that substance. Although some legal theorists have argued that patent principles derived from property and contract law require greater precision than is available from equivalency, the Court’s decisions on equivalency consistently emphasize the interest of justice, in aid of the constitutional purpose of technologic progress.

Patent Claims

The juridical approach to equivalency began before patents contained “claims” in the detail in which they are now written, and did not change as claim style evolved. The Patent Act of 1836 required all patentees to state what was “claimed,” a practice that was already the custom. See U.S. Patent Office, Information to Persons Having Business to Transact at the Patent Office (1836), reproduced in Karl Lutz, Evolution of the Claims of U.S. Patents, 20 J.Pat.Off. Soc’y 457, 464 (1938). The development of claim style2 was guided by growing cadres of professional patent examiners and registered patent attorneys, along with the growth of prior art and competing technologies. Indeed, the increasing specificity in claim style probably made it easier for the “unscrupulous copyist,” the words of Graver Tank, to appropriate the substance of the invention while evading the letter of the claims.
The public notice aspect of what the paten-tee “claims,” upon interaction with the patent examiner and on consideration of the prior art, is a powerful argument for strict literal reading of claims, even if the result is injus*1531tice in particular eases. However, the patent system is of ever-increasing importance, due to the dependence of industry on technology, the reduced opportunity to rely on trade secrecy because of today’s enlarged analytical capability, the ease and speed of imitation and modification once the innovator has shown the way, the harshness of modern competition, and the ever-present need for industrial incentives. These factors weigh on the side of the innovator, and thus favor a rule that tempers the rigor of literalness. See Patlex Corp. v. Mossinghoff, 758 F.2d 594, 599, 225 USPQ 243, 247 (Fed.Cir.) (“encouragement of investment-based risk is the fundamental purpose of the patent grant”), modified, 771 F.2d 480, 226 USPQ 985 (Fed.Cir.1985).
The principle of equivalency thus serves .a commercial purpose, as it adjusts the relationship between the originator and the second-comer who bore neither the burden of creation nor the risk of failure. However, there is also the major consideration of the progress of technology. How does the existence of a “doctrine” that transcends the statutory purpose of legal notice of the patent’s scope affect that progress? Does the doctrine of equivalents affect the research, development, investment, and commercialization decisions of today’s technologic industry, in a way that concerns the national interest?
And if not, what’s all the fuss about?

Innovation and Equivalency

Despite our national dependence on tech-nologic advance, there is a sparseness of practical study of whether and how the doctrine of equivalents affects modern industrial progress and the public welfare. However, a helpful debate is developing among scholars, centered upon the optimum scope of patent claims. For example, Robert P. Merges and Richard R. Nelson, On the Complex Economics of Claim Scope, 90 Colum.L.Rev. 839 (1990), suggest that the optimum claim scope is that which will promote “competition in research”; while Edmund W. Kitch, The Na-tture and Function of the Patent System, 20 J.L. & Econ. 265, 275-80 (1977), suggests that since competition in research is inefficient, broad claims to the originator would provide optimum incentives and serve the larger social welfare. These analyses have drawn thoughtful commentary and further development. For example, touching on the complexity of the issue of equivalency in Patent Law and Rent Dissipation, 78 Va. L.Rev. 305, 348 (1992), Mark F. Grady and Jay I. Alexander write that the “doctrine of equivalents is really the method through which the extent of an invention’s' technological signal is established.” These and other controversial theories aid our understanding, although practical implementation seems, to be quite elusive, for determination of the national interest is as complex as the many forms of technology and the varied research and industrial strategies of their development.
I need not , belabor that the economic risk in developing new technology is high, that the potential return must warrant the risk, and that the return must pay for the failures as well as the successes. See Paul A. Samuelson & William D. Nordhaus, Economics 658 (12th ed. 1985) (in general, a higher return is required for higher risk than for lower risk investment). The goal on which we must concentrate is the public welfare, as summarized in Mazer v. Stein, 347 U.S. 201, 219, 74 S.Ct. 460, 471, 98 L.Ed. 630, 100 USPQ 325, 333 (1954):
The economic philosophy behind the clause empowering Congress to grant patents and copyrights is the conviction that encouragement of individual effort by personal gain is the best way to advance public welfare through the talents of authors and inventors in “Science and useful Art.”
The principle is today of international force, as the United. States seeks to enhance its national strength and international trade with the aid of intellectual property. Indeed, recent economic history illustrates the stagnation of the economy coinciding, with periods of diminished industrial investment in tech-nologic advance. Professor Griliches, supra, at 291, wrote “Among the many explanations for the worldwide productivity slowdown in the 1970s, the exhaustion of inventive and technological opportunities remains a major suspect.”
The analytic complexity with respect to the doctrine of equivalents arises because tech-*1532nologic growth benefits not only from the activities of the originators, but also from those who improve, enlarge, and challenge. The larger public interest requires setting the optimum balance between the purpose of supporting the innovator, in the national interest, and the purpose of supporting improvement and competition, also in the national interest. The question that I have sought to explore is how the policy and law of the doctrine of equivalents affects this balance.

Improvements and Equivalency

Persons who appropriate the patentee’s concept may add technologic value in a variety of ways: perhaps by developing a different path to the new markets opened by the patentee, perhaps by adapting later-developed technology to enhance that of the pat-entee, perhaps by perceiving alternatives and opportunities from a different perspective than that of the patentee. All of these activities would bear lower risk to the appropriator if the patentee’s claims were strictly limited to their literal scope, for the patentee’s access to the remedy of equivalency imposes upon the appropriator the risk of litigation, damages, and injunction.
Most (but perhaps not all) students of technologic innovation today accept the proposition that there is a larger welfare benefit when the inventor is protected against appro-priability by a competitor who did not bear the commercial risk. The cost of substantially imitating an established product, with or without improvements, is usually lower, and always less risky, than the originator’s cost of creating, developing, and marketing the new product. Such a competitor can act in a shorter time than was needed by the paten-tee, and undercut the return to the patentee. See Edwin Mansfield, Mark Schwartz & Samuel Wagner, Imitation Costs and Patents: An Empirical Study, 91 Econ.J. 907 (1981). Because of the diminished risk-weighted incentive to the originator, it has generally been concluded that “total welfare, but not the welfare of consumers, would be increased by making it more difficult to produce close substitutes for existing products.” Stanley M. Besen & Leo J. Raskind, An Introduction to the Law and Economics of Intellectual Property, 5 J.Econ.Persp. 3, 6 n. 2 (1991).
These and other economic studies support the role of the doctrine of equivalents as a mechanism that makes it more difficult to produce close substitutes, whether by imitation or improvement. There are additional policy refinements, however, for improvements occur on a continuum between minor and major. Not all improvements are equal, and neither are their implications for techno-logic growth. Much of the current writing on the economic and developmental implications of the scope of patent rights is directed to technologies that are rapidly evolving, primarily in the fields of biotechnology and electronics. There is a growing body of interesting thinking about how to adapt the traditional modes of patenting to the scientific and commercial needs of these technologies. See, e.g., Pamela Samuelson, Randall Davis, Mitchell D. Kapor & J.H. Reichman, A Manifesto Concerning the Legal Protection of Computer Programs, 94 Co-lum.L.Rev. 2308 (1994) (proposing a “hybrid” protection for computer software beyond that available from existing legal regimes); Dan L. Burk, Biotechnology and Patent Law: Fitting Innovation to the Procrustean Bed, 17 Rutgers Computer & Tech. L.J. 1 (1991). Indeed, some of the analyses relating equivalency and scientific/technologic advance, in the context of modern innovation practices, suggest the thought that the doctrine of equivalents today serves the unexpected purpose of being the only readily available tool for application of the law to new technologies. See, e.g., Yusing Ko, An Economic Analysis of Biotechnology Patent Protection, 102 Yale L.J. 777 (1992) (analyzing decisions that applied the doctrine of equivalents).
■If minor improvements are likely to be captured by the doctrine of equivalents, this might cause the would-be competitor to move to diverging areas instead of simply tagging along at ■ the periphery of the patentee’s claims. On this theory the doctrine of equivalents, like the grant of broad claims, could encourage “leapfrogging” advances instead of minor improvements and substantial imitation. - This would enhance the growth of technology overall, and thus serve the public *1533welfare. The patentee too may be encouraged by the broader commercial protection of the doctrine of equivalents, particularly if the optimum commercial form turns out to be at the edge of the patent’s claims. A patentee may also be encouraged to continue to study and invest in fine tuning the invention, with the added security that the investment, if the project is successful, will be protected even if the patentee’s improvements are not separately patentable. See Suzanne Scotchmer, Standing on the Shoulders of Giants: Cumulative Research and the Patent Law, 5 J.Econ.Persp. 29 (1991) (discussing whether patent protection provides incentives for cumulative research). Conversely, it is of course possible that the originator will allow the technology to stagnate, or that would-be competitors would simply be diverted from the field; these possibilities, however, appear to depend less on the patent system than on many other factors. Each industry has its particular motivations, resources, and competitive situations. They have been well studied for fields that have high research costs, for these fields tend to be more dependent on the patent system as an innovation incentive. See, e.g., Henry G. Grabowski, The Determinants of Industrial Research and Development: A Study of the Chemical, Drug, and Petroleum Industries, 76 J.Pol.Eeon. 292 (1968). Merges and Nelson, supra, at 871, discussing the economic models broadly applicable to various types of claim scope, suggest that there is a point at which the available claims are so narrow that the advantages to imitation (as compared to innovation) become sufficiently large that erstwhile innovators will simply wait for something to imitate. Such a scenario is not uncommon for mature technologies. No analysis is generally applicable to all fields of technology and all competitive relationships, as illustrated in the growing literature on the function of patent-type economic incentives. See generally John W. Schlicher, Patent Law: Legal and Economic Principles (1992).

Competition and Equivalency

In thinking about the effect of the doctrine of equivalents on both innovators and competitors, one must consider how technology, the patent system, and competition interact. The question of equivalency is presented to judges after the competitive situation has crystallized, and thus we tend to focus on the technologic issues as they reach us in a lawsuit, and not on how the technology got to that stage. However, technologic advance, like scientific advance, usually proceeds in small, incremental steps, building on what has gone before, building on one’s own work and the work of others. The steps, accumulating, may eventually produce the next generation of technologic progress. Yet each step, viewed alone, may be an insubstantial change. Even minor improvements can displace the originator while adding little to advancing the field. See Besen & Raskind, supra, at 5 & n. 2. It is the insubstantial change that is caught by the law of equivalency.
Competition in research and development is important to the nation. There are important distinctions between competition in the research (inventing) stage and in commercial activity. Competition in research, however inefficient its economics, serves the advancement of knowledge in myriad ways. It is often observed that investment in commercialization tends to be more risk-sensitive than investment in research, apparently since the costs of product development and capital plant often dwarf the cost of making the invention. Yet industrial innovation is served by the patent system when the commercial investment is made. To the extent that the doctrine of equivalents enlarges the value of the patent to the innovator it also increases the net social value, as well as serving as a risk-reducing factor in commercial investment. The relevant economic theories on these points are varied, and the anal-yses are interesting. See, e.g., Janusz A. Ordover, Economic Foundations and Considerations in Protecting Industrial and Intellectual Property, 53 Antitrust L.J. 503, 506-07 (1985) (discussing the effects on innovative efforts of competition in research and development).
The complexities of these relationships far exceed the highlights I have touched. On the present state of the law I have concluded that the doctrine of equivalents, on balance, serves the interest of justice and the public interest in the advancement of technology, by *1534supporting the creativity of originators while requiring appropriators to adopt more than insubstantial technologic change.

Equivalency and Risk

Patent law provides rules of exclusion, priority, and competition that are understood by today’s industrial enterprises. Whether from the viewpoint of the originator of technology or the appropriator, the impact of the doctrine of equivalents is as only one of many commercial uncertainties and possibilities. I doubt if much, or any, reliance is placed by originators on the doctrine of equivalents when specific investment decisions are made; at least not by those who have studied precedent. The effect of the doctrine of equivalents as an innovation incentive is more generalized, more subtle.
I believe that the major contribution of the doctrine of equivalents is now, and always has been, to the idea of a fairer, less technocratic, more practical patent system; one that is oriented toward encouraging techno-logic innovation and discouraging free riding; one that is not at the “mercy of verbalism,” in the words of Graver Tank. In this way the doctrine of equivalents can contribute a degree of added investment confidence to the inherently risky environment of new technology. However, it will not serve that function if its application is so unpredictable that it can not be relied upon. Indeed, the determination of technologic equivalency should be reasonably predictable by not only the innovator but also the competitor. When applied to a particular patented invention, it should be reasonably predictable whether a specific device will be found “equivalent.”
The possibility of infringement litigation is a risk factor for both the patentee and the appropriator. The patentee will have weighed the strength, breadth, and enforceability of the patent, along with other market benefits and risks, before making a major investment in commercialization. In contrast, for the second-comer these risks are evaluated only after the patentee’s product has been proved successful in the marketplace. A competitor who operates within the “penumbra” of the claims, appropriating the inventor’s contribution while skirting the claims, may be deemed to have taken a calculated commercial risk that includes possible litigation. The degree of uncertainty of the outcome necessarily affects the commercial risk; the very existence of a “doctrine” that is applied variably by judges, and at great expense to the parties, has an effect on business decisions.
Some amici curiae complained that as lawyers they can not advise clients with confidence about how close they can come to a patentee’s invention, because of the doctrine of equivalents. However, no amicus guided us to resolution of the interests and rights of clients on both sides of the issue, or the national interest. Industry has been silent, except of course for Hilton Davis and Warner-Jenkinson, who have competently argued their positions, each finding sound support in this court’s precedent. Uncertainty at the margins of competing policies is not unique to patent law, and is probably no more prevalent than in other commercial causes of action. However, the court’s decision today provides no more certainty than did the 1950 decision in Graver Tank, leaving in place the problems of application of the doctrine that have concerned this court.
Uncertainty in the law always disserves the larger public interest, although usually one side or the other is served by it. The uncertainty in judicial application of the doctrine of equivalents surely serves the paten-tee, perhaps disproportionately. See Louis Kaplow, Rules versus Standards: An Economic Analysis, 42 Duke L.J. 557, 568-77 (1992) (discussing how the cost of compliance with law increases with imprecision of the law). A few authors have offered interesting suggestions for reducing the uncertainty while retaining the just purposes of the doctrine of equivalents, although most authors simply criticize the past without helpful suggestions for the future.
Economic analysis is reasonably consistent in its conclusion that technologic, commercial, and public interests coincide to favor law that favors the innovator as against the second-comer. However, the application of this analysis to the complexities of patent-dependent innovation is not fully understood. And the cases that reach us rarely present a simple choice, even when the “doctrine” is *1535viewed solely as an instrument of justice between specific parties. Graver Tank was an easy decision on its facts. Hilton Davis v. Warner-Jenkinson is not, in my view, an easy decision on its facts.

Rethinking the Doctrine

Reviewing past decisions that turned on equivalency, one perceives a few dominant scenarios. Usually the accused infringer was already in the commercial field of the invention, and the patented invention was making inroads into its business, providing competitive pressure for technologic response. Occasionally, although rarely, the second-comer made the invention independently.3 I have made a rough classification of four of the principal circumstances in which the doctrine of equivalents has appeared in litigation.
1. The patent actually claimed the aspect that is sought to be reached under the doctrine of equivalents, but:
(a) the broad claim that would have been literally infringed was held invalid, and the patentee seeks to recover part of that broader scope under the doctrine of equivalents; an example is Graver Tank;
(b) the broad claim that included literally the element for which equivalency is at issue is not infringed because of other limitations, and the patentee seeks to recover that broader scope through the doctrine of equivalents; an example is Malta v. Schulmerich Carillons Inc., 952 F.2d 1320, 21 USPQ2d 1161 (Fed.Cir.1991).
2. The patent claims did not include a known substitute for a component of the claimed combination:
(a) in Rite-Hite Corp. v. Kelley Co., 819 F.2d 1120, 2 USPQ2d 1915 (Fed.Cir.1987), a known ratchet and pawl mechanism in the claim was replaced with a known rack and pinion mechanism in the accused device;
(b) in Perkin-Elmer Corp. v. Westinghouse Electric Corp., 822 F.2d 1528, 3 USPQ2d 1321 (Fed.Cir.1987), a known tap transformer in the claim was replaced with a known loop transformer in the accused device.
3. “Obvious” changes are made in the pat-entee’s device, avoiding the literal scope of the claims:
(a) the accused device is in the space between the patent’s granted claim and the originally filed claim, which the examiner deemed overly broad and required to be narrowed; as in Laitram Corp. v. Cambridge Wire Cloth Co., 863 F.2d 855, 9 USPQ2d 1289 (Fed.Cir.1988);
(b) the accused device is in the space between the patent’s claim and the prior art; as in Wilson Sporting Goods Co. v. David Geoffrey & Assoc., 904 F.2d 677, 14 USPQ2d 1942 (Fed.Cir.1990).
4. Usually because of developments in technology, a part of the claimed combination is modified or becomes unnecessary:
(a) a step in a multistep process is combined with another step, as in Corning Glass Works v. Sumitomo Elec. U.S.A., Inc., 868 F.2d 1251, 9 USPQ2d 1962 (Fed.Cir.1989);
(b) a step in a multistep process is omitted, as in Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 4 USPQ2d 1737 (Fed.Cir.1987) (en banc).
In each of these four examples, infringement by equivalency was found in (a) but not in (b). It is not the doctrine of equivalents, but the uncertainty of its application, that causes the uncertainty in commercial relationships. Our decision today, while rejecting the proposed equitable considerations that would have added further uncertainty, does not answer the difficult question of improving the predictability and reducing the uncertainty of technologic decisionmaking. For this reason, *1536I have wondered whether' it may be possible to devise a better way to meet the needs now served by the doctrine of equivalents.
For example, the patent law places strong pressure on filing the patent application early in the development of the technology, often before the commercial embodiment is developed or all of the boundaries fully explored. Since the patentee is barred from enlarging the claims after two years from the date of issuance, later developments are excluded from the patent system unless they independently meet the criteria of patentability. From the originator’s .viewpoint, the inability to protect such developments may be a factor in recourse to the doctrine of equivalents. And from the viewpoint of the potential competitor, there is no opportunity to test possible encumbrances on later developments.
Most legal documents can be reformed, or amended, or supplemented. However, the available mechanisms for patent documents are extremely limited, for neither the reissue nor reexamination procedure permits adding to the disclosure. Thus some technologic variants can be reached only through litigation invoking the doctrine of equivalents. I invite creative thinking by the bar and technology communities, for if there were statutory procedures whereby patentees could protect their continuing work, there might be justification for limiting infringement to the literal scope of claims thus obtained.4 A statutory system that could accommodate the major factual scenarios- of technologic equivalency could provide added certainty both to patentees and .to those seeking to build on the subject matter of the patent. I commend the various suggestions already made in recent literature, for they start us on the path to a more useful mechanism , for resolution of the question of technologic equivalency.

Summary

The patent law is directed to the public purposes of fostering technological progress, investment in research and development, capital formation, entrepreneurship, innovation, national strength, and international competitiveness. Our review of the doctrine of equivalents takes place in this context, not as an abstraction insulated from commercial reality. The questions before us are not simple. However, until the technology community provides a better answer, I know of no improvement upon the Court’s holding that the doctrine of equivalents may be invoked when needed to “temper unsparing logic and prevent an infringer from stealing the benefit of an invention.” Graver Tank, 339 U.S. at 608, 70 S.Ct. at 856, 85 USPQ at 330 (quoting Royal Typewriter Co. v. Remington Rand, 168 F.2d 691, 692, 77 USPQ 517, 518 (1948)).

. I use the term "innovation” in Schumpeter’s meaning of the combination of invention and investment. Joseph A. Schumpeter, Capitalism, Socialism, and Democracy (3d ed. 1950). Schumpeter was one of the first economists formally to recognize that invention of itself produces no economic effect, while patent-based innovation has a positive impact on the economic system as new industries and new goods displace the old.

. The evolution from so-called "central” to "peripheral” claiming was gradual, and apparently unrelated to the difference between the wording of the 1836 phrase "particularly specify and point out the part ... which he claims,” Patent Act of 1836, ch. 357, § 6, 5 Stat. 117, 119, and the 1870 phrase "particularly point out and distinctly claim the part ... which he claims,” Patent Act of 1870, ch. 230, § 26, 16 Stat. 198, 201. The history of H.R. No. 1714 (the Patent Act of 1870) suggests that the change in the words of Section 26 was not deemed significant, for this change is not mentioned in the records of the enactment. See Cong. Globe, 41st Cong., 2d Sess. 2681-83 (1870). The Commissioner of Patents wrote that "[i]n 1870 the patent law was revised, but the revision was in the nature of a consolidation of the statutes then in force.” Charles Eliot Mitchell, Commissioner of Patents, An Address Delivered at the Proceedings of the Congress on the “Birth and Growth of the American Patent System" (1890), reprinted in Patent Centennial Celebration Proceedings and Addresses, 43-55, at 52 (1891). Commissioner Mitchell stated that the 1836 Act "created an epoch,” id. at 50, defining one of the important changes brought about by the 1836 Act to be "the distinction drawn between the description of the invention and the claim,” id. at 51, the significance of the claim being that it "set definite walls and fences about the rights of the patentee,” id.

. The patent statute permits an independent inventor to establish its prior right through an "interference” proceeding. Although Warner-Jenkinson states that it had the idea first and independently, it apparently did not attempt to provoke a patent interference with Hilton Davis. Part of the policy justification of the doctrine of equivalents is that if a person who is practicing substantially the same invention can not obtain priority as of right, through the statutory interference process, that person has no right to operate at the fringes of the prior invention. That is, the doctrine of equivalents assures no greater right to one who does not contest priority, than to one who loses a priority contest.

. For example, some countries have handled the issue of continuing developments through a statutory form called a "patent of addition”, a mechanism whereby a patentee can add additional disclosure and claims to a patent after it has issued.