• Home
  • The Doctrine of Equivalents in Patent Claim Interpretation

The Doctrine of Equivalents in Patent Claim Interpretation

Authors: Melody Musoni; Rory Moore.

A 2017 judgement by the United Kingdom Supreme Court has provided further guidance on the application of the so-called “doctrine of equivalents” to the question of indirect patent infringement in the United Kingdom.  This judgement may be influential on the development of South African patent law.

There are two types of patent infringement, textual infringement and non-textual infringement.  Textual infringement of a patent occurs when a device, product or process (the variant) contains all the features of a patent claim when literally interpreted.  This typically happens when a third party copies an invention directly or adds minor variations to the patented product.  Non-textual infringement, on the other hand, occurs when third parties attempt to design around a patent whilst making use of the basic idea of the patentee1 and varying, adding or omitting from the patentee’s invention to benefit therefrom without suffering the consequences of infringement.2

English patent law evolved from the “pith and marrow” interpretation (whereby a case of infringement was established only if the defendant’s variant product amounted to an immaterial variation)3, to the “purposive” Catnic4 test (whereby the test of infringement was whether a skilled person would understand that the patentee intended strict compliance with the patent claims such that any variant would fall outside the monopoly).  The Catnic test was summarised and further developed in the Improver case5.

A 2004 judgement in the Kirin-Amgen6 case reverted to a more literal interpretation of patent claims; after determining the meaning of a claim, the next step was to assess whether the alleged infringement was within the scope of this meaning.  If the alleged infringement was outside the scope of that meaning there was no infringement.

“Construction is objective in the sense that it is concerned with what a reasonable person to whom the utterance was addressed would have understood the author to be using the words to mean.  Notice, however, that it is not, as is sometimes said, “the meaning of the words the author used”, but rather what the notional addressee would have understood the author to mean by using those words.” (Paragraph 32).

If a claim is intended to cover products or processes which involve the use of technology unknown at the time the claim was drafted, then the patent specification and claims based thereon should be drafted so that a person skilled in the art would understand the description in a way which was sufficiently general to include the new technology.7

The law on this matter has recently received further exposition in a judgement handed down by the United Kingdom Supreme Court.  The case in question was Actavis v Lilly8.  The Supreme Court’s July 2017 judgement in this matter effectively broadened the scope of patent protection by introducing the doctrine of equivalents.

The World Intellectual Property Office (WIPO) has stated that “the doctrine indicates that an infringer should not be allowed to continue his actions where he basically makes use of the patented invention while merely substituting a variant for an element of the invention which is equivalent technically and functionally to the element as contained in the patent claim, irrespective of whether the variant used by the infringer turns out to be an improvement or otherwise.  Equivalence is restricted to those cases where the variant or variants used by the infringer function in substantially the same manner and produce substantially the same result as the element or elements contained in the claim or claims.”9  In other words, infringement under the doctrine of equivalents occurs when an allegedly infringing device, product or method performs substantially the same function, in substantially the same way, to achieve substantially the same result as the claimed invention.

The facts of the Actavis case were as follows:  Eli Lilly had been selling a patented cancer treatment under the brand name Alimta.  Claim 1 of the patent specified the use of a particular salt, pemetrexed disodium together with Vitamin B12 for the treatment of cancer.  The combination of the two avoided the side-effects of pemetrexed if used alone.  Actavis on the other hand intended to launch generic pemetrexed products that combined Vitamin B12 and different salts (pemetrexed diacid, pemetrexed ditromethamine, or pemetrexed dipotassium).  Eli Lilly argued that Actavis’s products infringed its patent because they consist of pemetrexed salt or the free acid with Vitamin B12, which represents the essence of the teaching and claims of the patent.  Actavis refuted these arguments on the basis that Eli Lilly’s patent was limited to pemetrexed disodium, and since Actavis’s products contained other salts, there was no infringement.

In addressing the alleged patent infringement, Lord Neuberger departed from the Kirin-Amgen approach and returned to the non-literal (“purposive”) test of infringement introduced in Catnic10 and subsequently developed in Improver11.  Lord Neuberger revisited Article 69 of the European Patent Convention (EPC) and the Protocol on its interpretation.  Article 69(1) EPC states: “The extent of the protection conferred by a European patent or a European patent application shall be determined by the claims.  Nevertheless, the description and drawings shall be used to interpret the claims.”  The relevant part of the Protocol to Art. 69 is Article 2.  This states that “For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is equivalent to an element specified in the claims.”

It was held that the problem of infringement is best approached by addressing two issues, each of which is to be considered through the eyes of the skilled person in the art.  The first question relates to whether the variant infringes on the invention by looking at the normal interpretation of the patent claims.  On a normal interpretation of Claim 1 of the Eli Lilly patent, the judge held that the Actavis products did not infringe the Alimta claims.

If there is no infringement based on the literal interpretation, the next leg of the test is whether the alleged infringement constitutes infringement of material variations.  In order to decide if the variations are material and to provide guidance on the interpretation of their judgement, the Supreme Court reformulated the Improver test and expressed their new questions as follows:

i) Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?  On this question, the learned judge concluded that the Actavis products achieved the same result in substantially the same as the patent since they both involved a medication containing pemetrexed anion and Vitamin B12.

ii) Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?  The court held that once the skilled person knew that the Actavis products achieved substantially the same result as the invention, he would have thought it obvious that this was so, particularly as he would have regarded investigating whether pemetrexed free acid, pemetrexed ditromethamine or pemetrexed dipotassium worked as a routine exercise.

iii) Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?  It was found that it was very unlikely that the skilled person would have concluded that the patentee could have intended to exclude any pemetrexed salts other than pemetrexed disodium from the scope of protection.  After this analysis, Lord Neuberger found that there was an infringement of Claim 1 of the patent by Actavis’s products.

The court noted that in a case where there is no literal infringement, a patentee has to establish that the answer to the first two questions was positive and the answer to the third question was negative.

An online article12 published by the UK firm of Bond Dickinson notes the following:

“Some commentators have suggested that the UKSC has merely confirmed the existing position under UK law.  However, such a view ignores the fact that the UKSC has grasped the nettle by expressly finding fault with the guidance that had been provided by Lord Hoffmann in the decision of the House of Lords (the predecessor to the UKSC) in Kirin-Amgen Inc. v. Hoechst Marion Roussel Ltd [2005] RPC 9.  Consequently, the UKSC has decoupled the scope of protection available to patentees against equivalents from an overly zealous construction of the claims.”

The same article concludes as follows:

“Whereas after Kirin-Amgen, there had been speculation as to whether regardless of Article 2 of the Protocol a doctrine of equivalents could be said to exist under UK patent law, the UKSC has clearly pronounced that Article 2 is broadly independent of the language used in the claims and that the test was, and remains one of, what represents a fair and reasonable degree of protection for the patentee.”

South Africa and the Doctrine of Equivalents
In South Africa, a patentee enjoys the right to exclude third parties from making, using, exercising, disposing or offering to dispose of, or importing the patented invention.13  South African patent law has developed a contextual approach to determine infringement.14  Patent claims must be interpreted by a skilled person in the context of the specification having regard to any definitions provided in the specification and whether any terms used in the claims have special meanings derived from the art to which they relate.  If there is an alleged infringement, the plaintiff bears the onus of proving patent infringement.  Determination of patent infringement is based on a comparison between the alleged infringing product and the words of the patent claims.   The courts have held that the language of a claim must be construed purposively so as to extract from it the essence or the essential elements of the invention.15

When it comes to the doctrine of equivalents, South Africa’s position is not clear and there have been no decisions by the Supreme Court of Appeal which would conclusively either require inferior courts to apply the doctrine of equivalents or not to do so.16  Some observers deny the existence of the doctrine of equivalents in South African law.17  Others have reasoned that because of the contextual approach to patent infringement, the scope of a claim may extend to non-literal equivalents.18

South African patent law takes cognisance of the legal implications of British case law.  Under ordinary circumstances the Actavis decision should have been expected to influence the elucidation and development of patent infringement law in South Africa.  However, the South African government is currently facing political pressure to change its patent laws in favour of public health.  The Actavis judgement and the doctrine of equivalents arguably promote the enjoyment of enlarged monopolies for patent proprietors against immaterial variants.  At least in the sphere of pharmaceutical patents, therefore, opponents may contend that the doctrine will act as a deterrent to innovation and competition from generic drug companies interested in working around patented inventions.  It will be interesting to see whether or not the Court of the Commissioner of Patents will be swayed by the Actavis judgement when next these issues come before it.

Contact Moore Intellectual Property for further advice on patent infringement issues.

Responsible Director:  Mr Rory Moore


+27 (0)31 785 1190

  1. WIPO Intellectual Property Handbook: Policy, Law and Use Chapter 2, p29.
  2. Raymond Zondo “The replacement of the Doctrine of Pith and Marrow by the Catnic test in English Law: A historical evaluation” 2012 Research Report UNISA.
  3. Clark v Adie (1877) 2 Ap Cas 315 (HL).
  4. Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183.
  5. Improver Corp v Remington Consumer Products Ltd [1989] RPC 69.
  6. Kirin-Amgen Inc and others (Appellants) v. Hoechst Marion Roussel Limited and others (Respondents) [2005] RPC 169.
  7. https://en.wikipedia.org/wiki/Kirin-Amgen_Inc_v_Hoechst_Marion_Roussel_Ltd
  8. Actavis UK Limited and others (Appellants) v Eli Lilly and Company (Respondent) [2017] UKSC 48.
  9. WIPO Intellectual Property Handbook: Policy, Law and Use Chapter 2 p32
  10. Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183.
  11. Improver Corp v Remington Consumer Products Ltd [1989] RPC 69.
  12. https://www.bonddickinson.com/insights/publications-and-briefings/supreme-court-emphasises-article-69-epc-2000-concerned-scope
  13. Patents Act 57 of 1978; Section 45.
  14. Alexis Apostolidis and Sophia Czarnocki 2017 (7th ed) Chapter 21 The International Comparative Legal Guide to Patents 126.
  15. Aktiebolaget Hässle and another v Triomed (Pty) Ltd 2003 (1) SA 155 (SCA) para 7.
  16. Dr Hans H. Hahn and Janusz F. Luterek “South Africa Patent Litigation” 2006 Jurisdictional Comparisons, European Lawyer, published by Thierry Calame and Massimo Sterpi.
  17. Ryan Tucker “Patent claim construction: Numerical limitations” 2016 De Rebus 34.
  18. Alexis Apostolidis and Sophia Czarnocki 2017 (7th ed) Chapter 21 The International Comparative Legal Guide to Patents 126.

Leave a Reply

Your email address will not be published. Required fields are marked *

Copyright © 2017 MIP SA (PTY) LTD.  All rights reserved.

Contact Us