Guest Post: Professor Sarnoff Warns India about the Doctrine of Equivalents

Readers may recollect our post discussing Ravi Kamal vs Kala Tech, where we asked if this was perhaps India’s first case invoking the “doctrine of equivalents”.

We profusely thank one of our readers who came back in our comments section stating that the doctrine of equivalents found mention way back in Raj Parkash Vs. Mangat Ram Chowdhry and Ors. AIR 1978 Delhi 1. Quoting Lord Denning in Beecham Group Limited v. Bristol Laboratories Ltd. and another, 1967 (16) R.P.C. 406 (12), the judge in Raj Parkash held as below:

“(25)…. Unessential features in an infringing article or process are of no account. If the infringing goods are made with the same object in view which is attained by the patented article, then a minor variation does not mean that there is no piracy.”

“(26) … By trifle variations if the effect obtained by the defendants is the same, and we hold that it is the same, then according to the rule enunciated in the Ampicillin case, referred to above, there is a clear piracy. The idea of the plaintiff which is a novelty is clearly infringed.”

While responding to the commentator, I stressed that a mere discussion of an “equivalents” or immaterial “variants” (as was the case in the Raj Parkash case) approach does not necessarily equate to an adoption of the “doctrine of equivalents” approach, a doctrine that primarily came out of US jurisprudence and has a specific conceptual connotation. I reproduce my reply below:

“I guess you’ve overlooked a critical difference between the US and UK position in this regard, something that my post highlighted. Ram Parkash endorsed a UK principle (pith and marrow/immaterial variation etc) that is quite different from a “doctrine of equivalents” (DOE) principle articulated by US courts. To understand this difference, one has to read the House of Lords ruling in Amgen vs Hoechst Marion. I’ve extracted the key portions below this message.

In Ravi Kala, the plaintiff argued the DOE (as understood in the US context) and counsel for defendants, Tulzapurkar did nothing (at least on record) to highlight that our courts haven’t endorsed DOE–rather, we’ve at best endorsed a pith and marrow/immaterial variation principle from UK courts. The point of the post was to highlight that we shouldn’t automatically assume that US principles of DOE apply in India!

Anyway, here is the extract from Amgen:

“At the time when the rules about natural and ordinary meanings were more or less rigidly applied, the United Kingdom and American courts showed understandable anxiety about applying a construction which allowed someone to avoid infringement by making an “immaterial variation” in the invention as described in the claims. In England, this led to the development of a doctrine of infringement by use of the “pith and marrow” of the invention (a phrase invented by Lord Cairns in Clark v Adie (1877) 2 App Cas 315, 320) as opposed to a “textual infringement”.

The pith and marrow doctrine was always a bit vague (“necessary to prevent sharp practice” said Lord Reid in C Van Der Lely NV v Bamfords Ltd [1963] RPC 61, 77) and it was unclear whether the courts regarded it as a principle of construction or an extension of protection outside the claims.

In the United States, where a similar principle is called the “doctrine of equivalents”, it is frankly acknowledged that it allows the patentee to extend his monopoly beyond the claims. In the leading case of Graver Tank & Manufacturing Co Inc v Linde Air Products Company 339 US 605, 607 (1950), Jackson J said that the American courts had recognised?

“that to permit imitation of a patented invention which does not copy every literal detail would be to convert the protection of the patent grant into a hollow and useless thing. Such a limitation would leave room for – indeed encourage – the unscrupulous copyist to make unimportant and insubstantial changes and substitutions in the patent which, though adding nothing, would be enough to take the copied matter outside the claim, and hence outside the reach of law.”

In similar vein, Learned Hand J (a great patent lawyer) said that the purpose of the doctrine of equivalents was “to temper unsparing logic and prevent an infringer from stealing the benefit of the invention”: Royal Typewriter Co v Remington Rand Inc (CA2nd Conn) 168 F2nd 691, 692.

The effect of the doctrine is thus to extend protection to something outside the claims which performs substantially the same function in substantially the same way to obtain the same result.”

Should India therefore opt for the British “purposive contruction” approach or the US “doctrine of equivalents” approach? Given our propensity to follow British jurisprudence more than US jurisprudence in IP cases and the Ram Parkash decision which expressly endorsed a UK “pith and marrow” approach (which was then reconceptualised as the purposive construction approach in the Catnic decision), it is more likely that Indian courts will adopt a “purposive construction” approach.

For those interested, please see my paper here which has a discussion on the “purposive construction” approach, laid down by Lord Hoffman in Amgen vs Hoechst Marion (pages 83-85 and pages 89-93). The paper is freely downloadable: click on the “download” tab right on top and then on the “SSRN New York USA tab” that opens up below it.

SpicyIP is honoured to have a guest post from Professor Josh Sarnoff in this regard. Professor Sarnoff, who teaches at the Washington College of Law, American University warns us about the dangers involved in a wholesale adoption of the “doctrine of equivalents”. He has written extensively (and critically) in this regard:

i) The Doctrine of Equivalents and Claiming the Future After Festo
ii) Abolishing the Doctrine of Equivalents and Claiming the Future After Festo
iii) The Historic and Modern Doctrines of Equivalents and Claiming the Future: Part I (1790-1870)
iv) The Historic and Modern Doctrines Of Equivalents and Claiming the Future: Part II (1870-1952)

In fact, two of the above papers won him the Emalee C. Godsey Scholarship Award in 2005 (The Historic and Modern Doctrine of Equivalents and Claiming the Future, Part I (1790-1870) and The Historic and Modern Doctrine of Equivalents and Claiming the Future, Part II (1870-1952)).

Professor Sarnoff is the Assistant Director of the Glushko-Samuelson Intellectual Property Law Clinic and a practitioner-in-residence at the Washington College of Law, American University, where he supervises law students in the practice of intellectual property law. He is a registered patent attorney, teaches patent law, and has been involved in a wide range of intellectual property legal and policy disputes.

He has published articles on patent law, has coordinated an academics’ position statement on patent law reform, has filed amicus briefs in the United States Supreme Court and the Court of Appeals for the Federal Circuit, and has been a consultant to the United Nations Conference on Trade and Development on intellectual property, trade, and environmental issues, and a pro-bono mediator for the Federal Circuit in patent cases.

He is also a dear friend and I am very grateful that he made time from his busy schedule to share his thoughts on a development that is of critical important to the development of patent jurisprudence in India. Here are his thoughts:

“It is important to address a basic concern raised by a recent Spicy IP post discussing the Ravi Kamal vs Kala Tech case i.e the belief that the doctrine of equivalents is needed to protect fairness to inventors/patent holders and to prevent fraud on the patent. Justice Black’s dissent in the Graver Tank case that established the modern doctrine of equivalents in the US (more on this below) was quite eloquent in responding to the perceived fairness of protecting a scope of invention beyond what the applicant actually claimed, so as to prevent supposed fraud on the patent (or patent holder). It also is a caution against using piracy rhetoric where it is not justified.

“I heartily agree with the Court that “fraud” is bad, “piracy” is evil, and “stealing” is reprehensible. But in this case, where petitioners are not charged with any such malevolence, these lofty principles do not justify the Court’s sterilization of Acts of Congress and prior decisions, none of which are even mentioned in today’s opinion …. [The Patent Act] provides that an applicant “shall particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery.”

We have held in this very case that this statute precludes invoking the specifications to alter a claim free from ambiguous language, since “it is the claim which measures the grant to the patentee.” … In seeking to justify its emasculation of [the statute] by parading potential hardships which literal enforcement might conceivably impose on patentees who had for some reason failed to claim complete protection for their discoveries, the Court fails even to mention the program for alleviation of such hardships [by reissuance of patents] which Congress itself has provided.”

(Reference: Graver Tank & Manufacturing Co. v. Linde Air Products Co., 339 U.S. 605, 613-15 (1950) (Black, J., dissenting) (quoting the majority opinion at 607-08, Rev. Stat. § 4888 (currently codified at 35 U.S.C. § 112, ¶ 2 (2000)), and Graver Tank & Manufacturing Co. v. Linde Air Products Co., 336 U.S. 271, 277 (1949)).)

For those who may want to know more about the origins of the doctrine of equivalents in the US, I wrote a two-part article that traces its history and demonstrates that until Graver Tank neither the Congress nor the Supreme Court had approved of patent protection that extended beyond the interpreted scope of the claim language, and that Congress in the 1952 Act did not impliedly ratify the radical change to the law that Graver Tank created.

The Supreme Court in Winans v. Denmeade (in 1853) had approved of non-literal claim construction in an era that predated peripheral claiming and the statutory requirement for distinct claims emphasized in the 1870 Act (following Evans v Eaton in 1822 and the 1836 Act’s codification of Evans’ requirement for formal claiming language), but in Brooks v. Fiske (also in 1853) the Court had also stated that patent protection was limited to the scope of direct application of construed claim language.

After the 1870 Act, the Court made clear that any unclaimed disclosed scope of the invention (i.e. any disclosed principle of invention that was not incorporated within the language of the formal patent claims, however broadly the claims were construed) was dedicated to the public and could only be reclaimed by reissuance (and then only within two years after issuance, as otherwise — by analogy — a statutory bar would apply to the published broader and unclaimed invention, given the two-year grace period that then existed, and it would be unfair to withdraw the invention from the public domain). Up to Graver Tank, the Supreme Court vacillated regarding how broadly (and non-literally) or narrowly (and literally) to interpret claims, but did not provide protection beyond their interpreted scope and application.

And that was always thought to be not only fair, but also all the protection to which the inventor/patent holder was entitled. The details are available at The Historic and Modern Doctrine of Equivalents and Claiming the Future, Part II (1870-1952), 87 J. Pat. & Trademark Off. Soc’y 441 (2005), and The Historic and Modern Doctrine of Equivalents and Claiming the Future, Part I (1790-1870), 87 J. Pat. & Trademark Off. Soc’y 371 (2005).

In another article, I explain how the doctrine of equivalents articulated in Graver Tank and applied (without statutory authorization) after 1952 by Warner-Jenkinson, Festo, and Federal Circuit cases has created a mess for implied disclaimer doctrines that affect claim construction and application for “literal” infringement and for doctrine of equivalents infringement analysis. Simply put, the clarity of using prosecution history to interpret the claims (however broadly or narrowly, non-literally or literally) and then to apply the construed claims to the facts was lost to a confusing morass of rules that arise in large part because of the existence of the modern doctrine of equivalents.

Currently, these rules require first interpreting the meaning of the claim language while deciding whether any prosecution disclaimer applies (using a different standards for determining if a disclaimer exists – a clear and unambiguous intent to disclaim — than for determining if prosecution history estoppel exists in the doctrine of equivalents context), then determining whether any prosecution history estoppel applies (after considering the new Festo rules on triggering a presumption by a narrowing amendment and then rebutting any such presumptive estoppel by looking to the technological unforeseeability of the equivalent rather than the legal ability to have drafted a claim that would have applied to it, motivations for making the narrowing amendments and whether they are tangential to the exclusion of the equivalent from the claim language, and other reasons why the patent holder is believed to have been unable to have claimed the equivalent at issue), and then revisiting claim construction by deciding whether finding equivalency infringement in the particular case would “entirely vitiate” the meaning of claim language that was already determined (by claim construction) not to apply to the equivalent.

This Alice in Wonderland approach is totally unnecessary, if one simply avoids the belief that the doctrine of equivalents is needed to protect fairness interests and thus protection beyond the interpreted scope of the claims is not warranted. That is the approach taken by the UK, requiring “purposive interpretation” but rejecting any extra-claim protection through a doctrine of equivalents. Kirin-Amgen, Inc. v. Hoechst Marion Roussel Ltd. [2004] U.K.H.L. 46. As the House of Lords stated in rejecting the American approach (and implicitly other European approaches), “American patent litigants will pay dearly for results which are no more just or predictable than could be achieved by simply reading the claims.” Para. 44. The details are available at The Doctrine of Equivalents and Claiming the Future After Festo, 14 Fed. Cir. B.J. 403 (2005).

Finally, in yet another article I explain why a modern doctrine of equivalents that protects inventions beyond the interpreted scope of claim language is not needed for fairness or efficiency and should be abolished. Abolishing the Doctrine of Equivalents and Claiming the Future After Festo, 19 Berkeley Tech. L.J. 1157 (2004).

As I explain, the fairness arguments lack theoretical justification, the doctrine imposes high social costs and likely impedes innovation, and doctrine of equivalents needlessly conflicts with other patent law doctrines and unduly complicates patent litigation procedures. For a good alternative view that provides a theoretical justification for a limited doctrine of equivalents, Michael Meurer and Craig Nard have an article providing social welfare arguments based on the social costs of avoiding unjustified claim refinement expenditures, in which they argue that the doctrine of equivalents should not apply to “startlingly new equivalents” (which are the paradigm equivalents for fairness arguments used to argue that the doctrine is needed) and in many other situations. (Reference: Michael J. Meurer & Craig Allen Nard, Invention, Refinement and Patent Claim Scope: A New Perspective on the Doctrine of Equivalents, 93 Geo. L.J. 1947, 1955 (2005)).

Mark Lemley and John Allison also have a good article explaining how the doctrine of equivalents has actually been applied by courts, reflecting that equivalency infringement is rarely found in practice. (Reference: Mark A. Lemley & John R. Allison, The (Unnoticed) Demise of the Doctrine of Equivalents, 59 Stan. L. Rev. 955 (2007). As they stated (at 958): “Even under the relatively permissive doctrine of equivalents rules in place before 2000, equivalents claims usually failed, most often on summary judgment. That became even more true after 2000, and the Supreme Court’s 2002 decision didn’t change the trend. In fact, district courts are more likely to reject doctrine of equivalents claims today than ever before.”


This is a doctrine that truly is not needed and causes more harm than good – it rarely succeeds but always needs to be evaluated and continues to cause confusion, uncertainty, and litigation costs. India would do well to follow the British and not the American model. But at least it should understand the public interests in avoiding interim injunctions based on infringement under an extra-claim-scope doctrine of equivalents.

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3 thoughts on “Guest Post: Professor Sarnoff Warns India about the Doctrine of Equivalents”

  1. Guru,

    Way too much information for one post.
    Now, I will have to book mark this one and read it in parts 🙂

    As always, very insightful and I do completely agree with the conclusion.


  2. Dear Sir,
    Apart from an argument based on infringement analysis, I have certain other reservations about the application of doctrine of equivalents/equivalence on different grounds although I am not sure at this point in time if my reservations are valid or even justified. Yet, I would like to think aloud and know what you and other well-read readers feel. Here it goes:

    I shall go back to the basics, specifically the fundamentals of patent law jurisprudence and proprietary jurisprudence in general. It would be banal to repeat the usual quid pro quo line about patents, however what exactly is the subject matter of protection and what constitutes possessory interest in patents would lead us to analyse the “quid” and the “pro” better.

    Every right has a few things in common, namely the owner of the right, the one against whom it is enforced, what does the right entail (content of the right), over what is the right exercised (subject-matter) and finally the pedigree of the right. Depending upon the nature of the right, one or more of these common features go on to define or characterize the right. The moment we talk of patents, we say that it is a negative right meaning thereby that the content of the right (patent grant) characterizes it primarily. The next question would be the subject-matter of the right to which the answer would be the invention, of course. But what is the “invention”? Is the invention the specific “inventive step” or is it the physical embodiment of the inventive step?

    If it is the former, then the debate on “software patents” would be redundant for the very argument against grant of such patents is that there cannot be a proprietary interest in something which is a principle of nature and consequently science and hence in public domain (this line of argument too may be questioned now for it assumes science to be an axiomatic edifice, which i would like to discuss later). Since patents are granted to contextual manifestations of science, namely technology, I am assuming that the physical embodiment of the inventive step is the invention and hence the subject-matter of the patent. If this is true, I find it difficult to reconcile the doctrine of equivalence with the aforesaid proposition. This is because as you rightly mentioned, the doctrine of immaterial variants differs from the doctrine of equivalence in a nuanced manner in that the latter tries to resort to purposive construction, simply put it goes beyond the written word and tries to capture the “spirit of the invention”. In doing so, I feel one traverses from a real plane to the plane of abstraction thereby militating against the very idea behind grant of patents i.e. to forbid untrammelled monopoly over ideas.

    So shouldn’t this alone forbid one from employing the doctrine of equivalents? Kindly let me know what you think.

    J.Sai Deepak.

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