The commercial value of a patent lies not so much in the claims made by the patent, but in the extent to which those claims are interpreted by the courts. Claims in a patent application, the exact legal language used to determine the scopes of the protection of a patent, are written in words, yet technology is not limited by words. A competitor who undertakes a small change in a device, a replacement of one chemical material by another, or a replacement of a mechanical element by another that would perform the same functionality would say that they do not fall within the literal meaning of the claims of a patent, although they have copied its fundamental inventive idea wholesale.

The doctrine is that the scope of protection under a patent is not only the actual words of the claims but also any substitutions that fulfil substantially the same purpose, substantially the same way, to produce substantially the same result - the internationally recognised Function Way Result test. In its absence, patents would be easily avoided through slight design changes making it commercially useless. But the doctrine has to be strictly circumscribed: otherwise its over-extension would upset the role of patent claims in creating public notice of where the boundary of exclusivity is.

The Patents Act 1970 of India does not mention anything about the doctrine of equivalents and methodology of claim construction. The law has evolved in each case, relying on the English common law principles and international precedents, to give rise to a jurisprudence that is analytically rich but internally contradictory. This blog follows that transformation from beginning with the principles that underlie the doctrine in the world, through the landmark cases in India and the questions which remain open and are left unsettled in the system of enforcement.

The Doctrine of Equivalents - The Global Framework

The United States Supreme Court made the statement of the doctrine of equivalents where two devices perform substantially the same work in substantially the same manner, and substantially the same result is achieved, the devices are identical, although they may be called by different names, form or shape. This Function-Way-Result test or Triple Identity Test has been furthered to, that the test should be administered to each element separately instead of to the entire invention.

The English law came up with an equivalent practice by the concept of purposive construction which stated that the construction of patent claims was not to be taken literally but purposely - what a person skilled in the art would believe the patentee intended to convey. The UK Supreme Court greatly clarified the stance and provided a two-step approach: (1) the normal purposive construction of the claims, and (2) a distinct question of equivalents - does the variant produce substantially the same result under substantially the same manner as the invention? Most importantly, Actavis believed that purposive construction and the doctrine of equivalents are not synonymous terms, but one is the other name of the same action.

Indian Statutory Framework-A conspicuous Silence

The act of patent infringement by equivalent is not defined in the Patents Act, 1970. Section 48 of the Act gives a patentee the right to exclude third parties in India in making, using, selling or importing the patented invention in India, but the scope of the "patented invention" in infringement is not specified in the Act either in Section 48 or in any other part of the Act, namely whether it is limited to the literal meaning of the claims or whether it covers equivalents.

Without statutory direction, Indian courts have in the past resorted to the common law doctrine of pith and marrow - an English pre-1970 notion, which enquires whether an alleged infringer has taken the substance of the invention, regardless of whether there were minor omissions or additions. The Supreme Court of India narrowly held that even a small difference cannot be considered as a defense against piracy and that the specification and claims should be interpreted in the light of a person of skill in the art in order to appreciate the gist and marrow of the invention. This doctrine is also very similar to, and not to be confused with, the modern doctrine of equivalents, and a legality error of confusion between the two has been a repeated issue of confusion in Indian patent jurisprudence.

The High Court of Delhi Rules Governing Patent Suits, 2022 added a procedural mandate of parties submitting claim construction briefs prior to the case management hearing, which is an important procedural measure, but does not answer the substantive question of which methodology to apply to claim construction a literal methodology, purposive methodology, or equivalents-based methodology and the relationship between the three in Indian law.

The Evolution of Precedents

A. F. Hoffmann-La Roche Ltd. v. Cipla Ltd.

The most impactful Indian case of claim construction has been as a result of high profile pharmaceutical patent litigation over the drug Erlotinib Hydrochloride (Tarceva). In 2009, the Single Judge of the Delhi High Court borrowed the English principle of purposive construction of Catnic, and inquired what an expert in the art would have construed the claims to include, rather than a literal interpretation. In a case that caused great controversy, the Single Judge significantly denied an interim injunction, on the ground of the public interest, that the right to life-saving cancer drug, which was available at an affordable price, was more important than the interim injunction to the patentee.

On appeal in 2012, the Division Bench upheld purposive construction as the correct method of construction, and that a claim to a chemical structure covers all polymorphs of the structure. Roche's patent was infringed by Cipla Erlotinib product despite the fact that the polymorph which was actually infringed was not expressly claimed. Nevertheless, the Division Bench failed to provide a clear distinction between purposive construction and the doctrine of equivalents, which raises the question of whether India does separate them as two dissimilar tools, as the UK Supreme Court later did in Actavis or regards them as identical exercise.

B. Novartis AG vs. Natco Pharma Ltd. (Delhi HC, 2021). CS(COMM) 62/2019

The Delhi High Court, in Novartis v. Natco, gave a set of guidelines on construction of claims that, in what was apparently a substantial doctrinal change, aligned itself closely with the literal rule, making it unjust to the public and an evasion of the law to interpret the words in the claims other than their ordinary meaning. Extrinsic evidence (including prosecution history and testimony of an inventor) was to be applied with extreme caution. This was seen as favouring a more rigid, more literal interpretation of patent claims and open to question as to how far Indian courts would go to offer protection against near-equivalents.

C. Sotefin SA v. Indraprastha Cancer Society and Research Centre (Delhi HC, 2022).

The first case in which a court directly addressed the doctrine of equivalents as an independent concept decided by Justice Sanjeev Narula in February 2022. This involved a Swiss patent on automated parking carriage systems (Silomat Dollies). A report commissioned by IIT Delhi revealed that 17 out of the 19 elements in Claim 1 were found in the allegedly infringing Smart Dollies - two elements (hinging and immobilisation of rear wheels) were not found.

Justice Narula found that non-essential elements of the invention could be removed or substituted without infringement, and applied the Function-Way-Result test, concluding that the Smart Dollies did the same work in the same way. It was the earliest Indian judgment to name the doctrine of equivalents and state the Function Way Result test to have been the standard applied - a historic advancement.

D. FMC Corporation v. Natco Pharma Ltd. (Delhi HC, 2022).

This case featured an alleged infringement of the process patent of FMC in producing the agrochemical Chlorantraniliprole. The Court applied the doctrine of equivalents to a process patent, but it is also important to note that in the case of process patents, the Function-Way-Result test is applicable element-by-element, not to the overall process. This was an important refinement and the first Indian ruling to deal with the doctrine, in the case of chemical process patents.

Open ended questions and their practical consequences

Despite the advancements represented by Sotefin and FMC, the doctrine of equivalents in India continues to be uncertain in three major areas, and the uncertainty has real consequences for technology and pharmaceutical industries.

The first relates to the interaction between the doctrine of equivalents and purposive construction. The two were considered as basically the same exercise in Roche v. Cipla, as a separate step in Sotefin and FMC, and seem to have been equated with literal interpretation later. The UK Supreme Court decision, which finally concluded that the two are distinct exercises, has not been considered by Indian courts and it remains to be seen if the UK approach is suitable for India. There is presently an uncertainty about whether the interpretation of patent claims in India is done in a purposive manner and then an equivalents analysis, or one method prevails over the other. In the case of technology companies with businesses in electronics and software, where patents are often formulated functionally, this uncertainty places equivalents analysis at the forefront of infringement analysis, without clear doctrinal guidance.

The second uncertainty surrounds the essentiality test - i.e. which elements are considered so essential that their change or deletion would negate an infringement. The term has been used by Indian courts but no test has been articulated. The assessment in India appears to be done on a case by case basis without any methodology, with inconsistent results.

The third, and most important, gap is the absence of any doctrine of prosecution history estoppel - the doctrine that limits the ability of a patentee to regain the ground it gave up during prosecution through the doctrine of equivalents. This has not been addressed in India. In its absence, the doctrine of equivalents has no internal constraint and there is a danger of its unprincipled expansion at the expense of competitors who have designed around the claims. For India's manufacturers, the uncertainty over the risk of design around raises transaction costs and litigation risk. For foreign patent owners, increasingly enforcing their patents in India as it emerges as a manufacturing and R&D hub, the lack of clarity also discourages investment in Indian patents. The situation is compounded by the fact that the WIPO International Patent Judicial Guide states Indian courts are required to follow the precedents of the English High Court on claim construction but these precedents have evolved since 2017, and Indian courts have not yet considered them.

The principle of equivalents holds a pivotal role in the patent enforcement system in India: it dictates to what extent patent claims may be practically enforced to safeguard innovation, and whether a small design change is enough to avoid being sued on infringement. The courts in India have been propelling forward in the right direction - starting with the purposive construction in Roche v. Cipla, the first outright application of the Function-Way-Result test in Sotefin, and the refinement of the process-patent in FMC - but the collective jurisprudence has been characterized by internal inconsistencies and leaves patent owners and market rivals without a clear guide.

The real-life merit of patent protection is centered on the doctrine of equivalence. Where a patent is easily attacked by small modifications, there is little commercial interest in innovation; a doctrine which has no principle of demarcation sets up uncertain liability to those who act in good faith. The patent system in India is becoming a more significant part of local and global innovation systems but it needs some clarification on both sides. The disconnect between the state of judicial affairs in India and its demands of the technology economy is a disconnect that is in dire need of legislative and judicial consideration.

Author :- Anushka Mitra, in case of any query, contact us at Global Patent Filing or write back us via email at support@globalpatentfiling.com.