Case Comment: Ravi Kamal Bali v. Kala Tech. and Ors[1].


A patent allows an individual to protect and safeguard his/her innovation from its competitors. The patent laws state that every inventor has to provide concise aspects of their works which helps in balancing the interest of an individual with the interest of the public. [2]The patents are often interpreted literally based on their claims. If however, such limitation is removed then it would make patent rights redundant. The Doctrine of Equivalents helps in countering such limitations while promoting innovation.

The case comment is an analysis of the case Ravi Kamal Bali v. Kala Tech. and Ors[3]. Wherein India, applied the Doctrine of Equivalents for the first time. The case study helps in understanding the implications of the abovementioned Doctrine on the Indian Patent System.

Facts of the case:

The case of Ravi Kamal Bali v. Kal Tech and Ors, throws light on the Doctrine of Equivalents in India. In the present case, the plaintiff Mr. Ravi Kamal Bali had filed a suit seeking damages and an injunction from the Hon’ble Court to prohibit the defendants from making, using, selling and distributing the tamper locks[4].

The Hon’ble court issued a patent and its certificate of registration on 29.02.1994 to the plaintiff in lieu of the tamper locks/seal and on 12.03.1994 apatent of addition was issued for an improvement made on the tamper proof lock/seal under the name of “TechLock” .The plaintiff alleges that the defendant no.1 was manufacturing and selling a similar product under “SEAL TECH” with the aid of defendant no.3 who was employee of the plaintiff till 2002.

The plaintiff pleaded the Doctrine of Equivalents i.e it is not necessitated that the goods have to be identical in all aspects in order for it to be considered as an infringement on the patented product. In alleging so, the plaintiffs put forward the similarities between the two products .The Defendants contended that the goods sold by them under the name “Seal tech” is distinct by stating that it is rectangular in shape and not ‘V’ in shape and doesn’t require compress pressure among others.

Issue of the case:

The issue before the Hon’ble Court was: Whether the product of the defendant “Seal Tech” infringes upon the patented product of the plaintiff ?

Rules Applied:

The rules that have been dealt in the present case comment are as follows:

  • Section 54, Indian Patent Act, 1970
  • Section 10 , Indian Patent Act, 1970
  • Doctrine of Equivalents


The Hon’ble Court ruled in favour of the plaintiffs and opined that the built, functionality and shape of the product has to be considered. Moreover, the court stated that the usage or non-usage of force in the process and the shape of the product are a marginal difference and thus cannot be considered differences. The court took notice of Section 54 of the Patents Act, 1970 and held that “only the patentee of the main invention is entitled to improve or modify the main invention and claim patent for such or else it would permit anybody to benefit from it by exploiting the main invention”. [5]Thus, in order to prevent fraud the court applied the Doctrine of Equivalents opined that the defendant’s product is an infringement on the patent of the plaintiff.

In Warner Jenkinson Co. v. Hilton Davis Chem. Co, the court while deliberating on the Doctrine of Equivalents stated that in applying the doctrine the invention as a whole should not be taken in consideration. [6]It stated the invention has to be broken down into its different features and then utilize that specific feature to assess the accusation and the accused invention. Whereas, the Ravi Kamal case did not adhere to the above mentioned criteria but also did not abide by the All Elements Rule[7]. [8]

There are certain implications of the Doctrine of Equivalent on the Indian Patent System. Firstly, the Doctrine varies from the objectives of Patent Law System. The object of Patent Law is to promote invention, scientific research, new technology and progress[9]. This Doctrine would make it difficult for inventors to modify or create a product around a patented product as the scope of the doctrine has not been defined in the judgement.

Secondly, it violates Section 10 of the Patents Act, 1920[10]. In Bayer Corporation and Ors. v. Cipla, Union of India and Ors., the Court opined that the claim for a patent has to full and particularly describe the invention, its operation and use and method by which it is performed[11]. The application of this Doctrine would make stating the specification of the product in the application process impractical. It will create ambiguity when it will not be interpreted literally. The claims which state ‘what it is’ and ‘what is not protected’ will become unclear. This will contradict the judgment given by the Apex court in Bishwanath Prasad Radhey Shyam v Hindustan Metal Industries, which stated that “the proper way to construe a specification is not to read the claim first and then see what the full description of the invention is but first to read the description of the invention, in order that the mind may be prepared for what it is, what is to be claimed, as the patentee cannot claims more than he desires to patent”.[12]


The essence of the Doctrine of Equivalents is to preserve and protect the patented product. However, its application in the Indian System is yet to be ascertained. The author agree with the rationales of the judgement in Ravi Kamal Bali. V. Kala Tech and Ors to the extent that marginal differences are not sufficient to distinguish a product from another and helps in curbing chances of fraud in such cases.

The author believes that the Doctrine of Equivalents is at a nascent stage in India and thus can be problematic. For instance, the Doctrine of Equivalents can intervene with the function of public notice of claiming requirements. Therefore, if an individual having looked at the patent invents and create a product which goes beyond the literal interpretation of the claims, then he infringes the patent according to the above mentioned Doctrine.However, the author believes that the judgment did not spell out the guideline, criteria’s or the tests which should be considered while applying the Doctrine of Equivalent in India.  Thus, in order to apply the above mentioned Doctrine in India it is necessary to cull out the scope and extent of the Doctrine in order to truly achieve the object of the Doctrine.

[1] [2008] (38) PTC435 (Bom)

[2] S.10(4) Indian Patent Act 1970

[3] Ibid.

[4]Supra note1

[5]Supra note 1

[6] [1997] 520 U.S. 17, 21

[7] The “All Elements”, test says that the doctrine of equivalents must be applied to all the individual elements of the claims and not the claimed invention as a whole

[8]ToshitShandilya and ShwetaDuggal“ Ravi Kamal Bali v. Kala Tech: Doctrine of Equivalents a boon to investors?” NLIU     JIPR <; accessed on 19 June 2020

[9]M/s. Bishwananth Prasad RadheyShyam v. Hindustan Metal  [1982] AIR 1982 SC 1444

[10]Patents Act 1970, s 10 (5):  define the limits of the invention by giving clear and succinct claims and which is based on the matter disclosed in the specification

[11][2009](41) PTC 634 (Del)

[12]Supra note 6

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