Doctrine of Equivalents in Indian Patent Law
INTRODUCTION
Patents are a specialized form of intellectual property rights granted for scientific inventions and new creations that reflect novelty. While these rights strictly prohibit unauthorized parties from producing or selling a protected invention, attempts are often made to bypass legal consequences by making minor, insignificant modifications. The Doctrine of Equivalents serves as a vital interpretative tool to counter such tactics. It addresses infringement by focusing on the “pith and marrow” of an invention rather than its exact replication. This doctrine has been adopted worldwide and has been increasingly applied in the Indian Patent litigation. This article examines the doctrine’s definition, the functional tests used to determine equivalence, and its evolving legal framework and application within the Indian context.
Patent is a niche form of intellectual property where exclusive rights are granted for an invention. While other forms of intellectual property like trademarks, copyrights, design are awarded for creative/artistic works, patents are usually awarded for scientific inventions and new creations. The grant of a patent right restricts non owners from producing or selling the invention. Patent rights also incentivize innovation and meaningful contribution. For the grant of a patent, the invention must possess novelty, must have an inventive step, and must have applicability. The Doctrine of Equivalents furthers the protection against infringement of patents. Patent infringement is of two types – direct and indirect. Direct infringement refers to a circumstance when a third party wilfully or intentionally steals the technology from the inventor without prior permission. This means when someone directly makes, uses or sells the patented invention. Indirect infringement refers to infringement that does not give a clear indication that the patent is bought and sold in the market. Moreover, there are infringers who make minor tweaks and insignificant modifications to the original inventions. This doctrine prevents such infringers from escaping liability. Therefore, the doctrine of equivalents tackles the issue of non-literal or indirect infringement. Thus, it ensures that the fundamental nature of the invention is protected and true innovators are rewarded while infringers are deterred.
This Doctrine originated in the nineteenth century in the United States in the case of Winans v. Denmead1. In this case, the Plaintiff had patented a conical car for the purposes of transport of coal and the Defendant manufactured cars for the same purpose but with an octagonal shape. Here, the Supreme Court of United States held that this act is infringement by equivalence as the same principle was employed in the same manner to achieve the same result. Thus, the patent was held to be infringed despite the difference in shape.
With the passage of time, this doctrine has been adopted worldwide and its acceptance has helped in the safeguarding of patents in various sectors such as engineering, information technology, pharmaceuticals. In India, the first case explicitly deliberating on this doctrine was in 2008 and the application of this doctrine has since increased in patent litigation. This article explores the doctrine’s definition, application, legal framework, judicial evolution, criticisms, and future prospects in the Indian context.
The doctrine serves as a tool of interpretation in patent litigation concerning infringement. Through the application of this doctrine, a broader and liberal interpretation is given which goes beyond the strict binary of “infringement”. In simple words, a process or product infringes another patent if is substantially or functionally equivalent to an invention despite absence of exact replication. This doctrine deals with the crucial issue of “designing around” i.e., the making of deliberate minor and irrelevant changes to a patented invention in order to reap its benefits. The rationale of this is to protect the true innovator’s rights against minor and unnecessary variations made to avoid direct infringement.
Moreover, the doctrine delineates between essential and non-essential features. The former term refers to the core of invention and it cannot be substituted while the latter term refers to elements that can be varied. The non-essential features are often varied of a legitimate invention to infringe the product or process while falling outside the traditional scope of infringement. Through application of this doctrine, each essential element must have a corresponding equivalent in the accused product. This becomes particularly important in the case of mechanical and chemical patents where details are the quintessential.
This doctrine is two-fold, consisting of essential elements test and triple identity test. The Elements test refers to the checking of each element of the patent. The equivalence will be analysed on an element-to-element basis rather than assessing the innovation as a whole. For a patent to be infringed, it is necessary that all the core elements are present even if inessential elements [such as shape of the car in Winans case] are modified. Through the elements test, the details of the patent are delved into and the doctrine is applied to each claim element. The triple identity test brings in a three-pronged approach. It checks if the accused product i. performs substantially the same function ii. In substantially the same way and, iii.to get substantially the same result. Thus, through application of this test, the functionality, manner, and end result is assessed. On co-existence of these three points regarding function, manner, and, result then the accused product is considered to be an infringer.
On one hand it can be said that the doctrine brings in an approach which is too liberal and expansive. Whereas, on the other hand, it can be argued that the doctrine brings in equitable protection while demanding an evidence based and case specific analysis by breaking down of the invention down to its elements and function. The doctrine faces a significant limitation of prosecution history estoppel. According to this estoppel, patent claims are to be interpreted while considering the existing records of the patent office during application process. Through the application of this, subject matter that was surrendered during application of a patent cannot be reclaimed later through the doctrine. This estoppel creates a presumption that equivalents within the surrendered territory are excluded. The Doctrine of Pith and Marrow is often incorporated with the Doctrine of Equivalents in patent law. According to the former doctrine, the “pith and marrow” i.e., the core or heart of the invention is assessed and not just literal words of the patent. This approach brings in a purposive claim construction and identifies that if a variant has no material effect on functionality, infringement may be found. The burden lies on the patentee to prove equivalence, often through expert evidence. Thus, both of these doctrines address the issue of non-literal infringement and prevent colourable imitation or minor changes made to escape the literal claim scope.
Legal Framework
The Patents Act, 1970 in India is the central legislation and statutory backbone of patent law in India. The Act does not codify or make mention of the doctrine. The infringement of patents is enshrined under Chapter 13, sections 104 to 114 of the Act. According to the Act, infringement means unauthorized production, usage, sale or import of patented invention during its term. The remedies for infringement include injunctions, damages, and accounts of profits. The limitation period for filing patent infringement lawsuits is three years from the date of said infringement. This doctrine like other common law principles or international doctrines
has developed through judicial interpretations. There are no legislative guidelines or clarifications for equivalence tests. While the Act defines the traditional bounds of infringement, the doctrine goes beyond it and provides a liberal interpretation. Therefore, the scope and application are this doctrine remains judge made while emphasis is laid on equitable relief and claim definiteness.
Judicial Developments
The first case in Indian jurisdiction to explicitly mention the doctrine was Ravi Kamal Bali v. Kala Tech2 in 2008 in front of Bombay High Court. In this case, the Plaintiff alleged infringement of their patented tamper proof locks and seals by the Defendant. It was alleged that the Defendants products had the same functional features with cosmetic and superficial changes. Thus, the High Court of Bombay addressed the question of whether the defendants’ products infringed the plaintiff’s patents for tamper-proof seals. The court found that the defendants’ products operated on the same principle as the plaintiff’s patented invention, thus constituting infringement. However, the court dismissed the plaintiff’s motion for an injunction due to delay and misrepresentation in seeking interim relief without notice to the defendants.
In the case of Bajaj Auto Ltd. v. TVS Motor Co. Ltd3., the Madras High Court was concerned with the alleged infringement of Bajaj’s DTS-I patent. The Defendant had taken the Plaintiff’s technology and made a minor change i.e., addition of an extra valve. The test of purposive construction of patent claims was adopted while applying the doctrine of pith and marrow to assess whether infringement by equivalence was committed. The Court held that the essence or core inventive step was emulated with minor changes. Thus, the Plaintiff was granted an interim injunction. Despite the Apex Court vacating this injunction at a later stage, this judgment remains persuasive.
Another landmark case dealing with the doctrine in chemical industry is FMC Corporation & Ors. vs Natco Pharma Limited4. The Plaintiff approached the Delhi High Court under sections 48 read with 108 claiming that the Defendant’s process of manufacturing CTPR infringed their patent. The Plaintiff used sulfonyl chloride whereas, the Defendant used thionyl chloride and the Plaintiff argued that this is a mere substitution. However, in the Plaintiff’s process, the chemical was used as a coupling agent whereas, the Defendant’s process, the chemical was used as a chlorinating agent. Therefore, the Defendant made a change in the process and additionally, the function of the chemical was different. The court ruled that the doctrine will not apply when an essential element of the patented process is changed rather than substituted with an equivalent. Thus, the court held this not to be infringement by application of doctrine of equivalents.
In the case of Sotefin SA v. Indraprastha Cancer Society And Research Center & Ors5 The Delhi High Court dealt with the alleged infringement of Patent named “Smart Dollies” pertaining to self-propelled carriage on wheels. The Defendant’s product had two missing parts i.e., immobilization of rear wheels and hinging. However, rest of the elements were present. The Court went beyond the literal comparison of claims and adopted a purposive construction. It was held that the missing elements were not essential and the Defendant’s product performed the same function, in the same manner, to achieve the same result. The core inventive step remained the same and infringement is not restricted to rigid letter of the law. Thus, the Court granted an interim injunction.
In the case of SNPC Machines v. Vishal Choudhary6, the Plaintiff filed a patent infringement suit against the Defendant pertaining to brick-making machines. The Plaintiff and Defendant’s product featured a brick making machine, whereas, the latter’s machine lacked cabin, steering mechanism and was not self-propelled. The Plaintiff argued that these differences were not essential and pleaded the Court to apply the doctrine of equivalents. The Delhi High Court agreed with the arguments of the Plaintiff and held that the brick-making machine was functionally same, operated in the same manner, to produce the same result. Thus, the Court granted an interim injunction while focusing on functional equivalence and core inventive features rather than literal replication or copying.
Conclusion
In conclusion, the doctrine remains significant for patent enforcement and litigation in India. Indian jurisprudence in terms of the application of this doctrine still has a long way to go in comparison to American or British jurisdictions. This Doctrine has remained vital and has constantly evolved through judicial developments to address non-literal infringement.
Moreover, by integrating other tests and principles such as purposive construction and pith and marrow, the Courts have protected various innovators and their inventions. The analysis of case laws showcases a relief oriented and liberal perspective undertaken by Courts. It continues to be relevant in fields like chemistry where minor changes in chemicals can be disguised as copying. The Courts have been mindful while applying this doctrine prudently and cautiously. The changes or variations made must be insignificant, the core inventive step and essence of the invention must be retained. The protective framework of doctrine of equivalents has not just prevented infringement of patents, but has also fostered confidence in innovators that their innovations will be protected. This brings in legal certainty for public and deters escape from the ambit of infringement. The doctrine has expanded on rewarding true invention while promoting progress which is synonymous with the spirit of patent law. With India’s ever evolving innovation ecosystem, the doctrine of equivalents will remain an essential tool for balancing patent protection with technological advancement.
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