An invention has to satisfy the conditions of Novelty, Inventive step, and Industrial Applicability in order to be patentable in India, just like any other jurisdiction. However, along with the said pre-requisites, the Indian Patent Law provides an additional bar to the patentability of inventions by defining non-patentable subject matter under Section 3 of the Indian Patents Act. Therefore, in India, the inventions should not only be novel, inventive, and industrially applicable but also should not attract any of the provisions of non-patentability laid down in Section 3 of the Patents Act in order to be patentable. The subject article particularly discusses the imposition of Section 3(d) of the Patents Act on chemical and pharmaceutical inventions.

Section 3(d) of the Patents Act

Section 3(d) is unique to the Indian jurisdiction and is contemplated as additional scrutiny for patent applications. The intention of keeping the said section is to prevent the ever-greening of the chemical compounds and to provide a fair chance to all the players to monopolize the market for a specific duration.

Section 3(d) of the Patents Act bars, “the mere discovery of a new form of a known substance which does not result in the enhancement of the known efficacy of that substance or the mere discovery of any new property or new use for a known substance or of the mere use of a known process, machine or apparatus unless such known process results in a new product or employs at least one new reactant. Explanation. -For the purposes of this clause, salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations, and other derivatives of known substance shall be considered to be the same substance, unless they differ significantly in properties with regard to efficacy,” from patentability. As noted, the said section is divided in to four categories i.e., “mere discovery of a new form of a known substance,” “mere discovery of any new property for a known substance, “mere discovery of new use of a known substance,” and “mere use of a known process, machine, or apparatus.” Any invention lying in the ambit of any of the above categories is considered non-patentable.

Due to the restrictive approach of Section 3(d) of the Patents Act, the pharmaceutical companies of the national and foreign jurisdictions usually presume the said section as a deterrent to the patentability of their products or process, if they belong to the category of a new form of a known substance or a process of preparing a known substance. Thus, they are reluctant to file such patent applications in India. On the contrary, after reviewing several such patent applications, it is found that such presumptions cannot be generalized to every chemical or pharmaceutical invention. It is noted from the analysis that most of the time, the Controller in charge of such patent applications applies the said section unwarrantedly. In order to ensure the valid application of the said section, the Applicant is required to perform the following checks and strategies:

  1. Is the subject matter considered novel by the Controller or is it novel by way of an amendment/argument? If yes, then the subject matter cannot, in any way, fall under the known process/substance as categorized under Section 3(d). Therefore, submitting a detailed and persuasive reply regarding novelty and inventive step objection along with the supportive arguments related to technical effects/advantages shown by the recited features of claims shall suffice the requirement to address the said objection.
  2. In case, the subject matter falls under any of the categories of the Section 3(d), then the arguments pertaining to enhanced efficacy of the subject matter over the known subject matter shall be required to address the objection. However, many controversies exist around the interpretation of the term “efficacy.”

The subject article shall now throw some light on the interpretations of the term “Efficacy” under Section 3(d) for inventions related to a product. Further, the relevance of Section 3(d) in the context of inventions related to a method/process has also been discussed.

Interpretation the  of term “efficacy” in the context of inventions directed toward a product

From a literal interpretation of the Section 3(d) of the Patents Act, for inventions relating to a product, it is understood that new form of a known substance, the new property of a known substance, and new use of a known substance are not patentable unless an enhancement of efficacy is shown. The said section further provides an explanation regarding the different forms of a known substance such as isomers, salts, ethers, etc. It also states under the explanation that such forms of known substance are patentable if they “differ significantly in properties with regard to efficacy.” However, the terms such as “efficacy”, “properties” and “derivatives” are not defined clearly anywhere in the statute. The question, therefore, lies before the Applicant that which property(ies) should differ between a substance and a new form of that substance and how efficacy has to be demonstrated.

While comparative data demonstrating an enhancement in properties such as bioavailability, flow ability, disintegration property, etc. of the new form of the known drug is sufficient for patentability in the other jurisdictions, such data may not suffice to overcome the imposition of Section 3(d) in India.

It is because any minor modifications in the already existing product are exempted from being patentable unless it shows enhanced or improved efficacy. The term “efficacy” is discussed in the order passed by the Honourable Supreme Court of India in Novartis AG v. Union of India and Ors. [(2013) 6 SCC 1]. It was clarified that, the test of efficacy would depend upon the function, utility or the purpose of the product under consideration. Therefore, in case of inventions directed towards a new form of a known drug or medicine, the function or utility of any drug is to cure a disease, therefore in the context of drugs and medicines, the properties or data, which show that the new form of the drug/medicine has increased efficiency or ability to cure a particular disease as compared to the already existing drug/medicine is considered to be relevant data for proving “enhanced efficacy.” In fact, in the Novartis case (supra), the Court held that mere demonstration of enhanced bioavailability property of the new form of the drug is not sufficient to satisfy the “efficacy” parameter of the Section 3(d) of the Patents Act. Therefore, not all advantageous or beneficial properties are relevant, but only such properties that directly relate to efficacy can be taken into account. The Court in the Novartis case, further stated that whether or not an increase in bioavailability leads to an enhancement of efficacy in any given case must be specifically claimed and established by research data. Therefore, it was concluded that for any invention relating to, for instance, such as salts or different polymorphic form of a drug, enhancement of “therapeutic efficacy” should be validated by the experimental data.

Section 3(d) for the Patents Act for inventions directed towards a method

Section 3(d) of the Indian Patents Act bars the patenting of a “mere use of a known method” unless such known method results in a new product or employs at least one new reactant. In other words, in order to overcome the imposition of the said section, the method should not be a mere use of a known method or should involve a new reactant or should result in a new product. Alternatively, if the claimed method has a significant improvement over the existing prior arts, then the claimed method can escape from the imposition of Section 3(d) of the Indian Patents Act, 1970.

In recent judgement of the Delhi High Court in Chugai Seiyaku Kabushiki Kaisha versus Controller of Patents and Design C.A.(COMM.IPD-PAT) 4/2021 dated April 6, 2022, the Delhi High Court held that the method of producing a solid form (tablet) of pre-existing drug via direct compression method is not patentable.

This case was directed to the Appeal filed by the Chugai Seiyaku Kabushiki Kaisha, the Appellant, challenging the order passed by the Controller of Patents, the Respondent, in the matter of the Appellant's patent application No.201617023236, wherein the Application has been rejected by the Respondent on grounds of lack of inventive step and Section 3(d) of the Patents Act.

The subject invention specifically provides a method for preparation of a tablet comprising Tofogliflozin from the powder mixture by direct compression. The Appellant asserted that its invention provides method of producing a tablet comprising Tofoglifozin with improved disintegration and dissolution properties as compared to the conventional production methods such as wet grinding and is hence entitled to grant of a patent.

Further, the Appellant emphasized that the Respondent in its order passed with respect to the Patent Application has wrongfully imposed Section 3(d) of the Patents Act as the invention is directed towards a process for manufacturing of a monohydrate crystal form of Tofogliflozin in tablet form. The Appellant submitted that the Respondent's statement that the new use of a known drug is absurd as the case is not a new use of a known drug but method of producing more stable drug in the form of a tablet from the original drug Tofogliflozin. The Appellant accentuated to the Court that the pharmaceutical composition was not sought to be patented but merely the process was sought to be patented.

The Respondent contended that the Appellant has various patents with respect to the compound in question. These patents are cited as the prior art documents. The prior art documents clearly disclose the compound in question as well as the tablet form of the compound. Therefore, the Respondent asserted that the Patentee is attempting to evergreen the patent and mere method for preparation of a tablet form of Tofogliflozin by direct compression method would not be patentable for the reason that it is not a new method or a new product and as the same would not constitute enhancement in therapeutic efficacy of the known drug. 

The Court has upheld the Respondent's finding that the Appelant's application is directed towards a tablet form of the compound Tofogliflozin, wherein the tofogliflozin is present in a form of monohydrate crystal, and the said compound Tofogliflozin is a pre-existing drug in the prior arts, therefore the application is not a new product or new process. The prior arts clearly show that the compound Tofogliflozin is clearly covered and tablet forms are also covered. Specifically, the various forms in which the said medicine can be administered are mentioned and covered. The Court found that the superior disintegration and elution properties demonstrated by the Appellant of the tofogliflozin tablet obtained by the direct compression method, would not entitle the Appellant to a patent as it would involve the same components of the compound in question as in the prior arts, apart from use of the disintegrating agents and lubricants. Various elements of the same active ingredient are present in the monohydrate crystal is disclosed in the prior art documents.


The Court has also aligned its decision with the Respondent's findings that the Appellant intends to patent the tablet form of Tofogliflozin, through a method patent (product by process), and hence in the absence of enhanced efficacy the application is clearly hit with Section 3(d) of the Patents Act. The Court took the judicial precedent set in Novartis case (supra) that mere method of preparation of a table form of Tofogliflozin by direct compression method would not be patentable as the same would not constitute enhancement in therapeutic efficacy. Further, the Court negated the Appellant's arguments about the comparative data that has been set out in the examples. The Court pointed out that the patent application does not establish what would be the effect of early or shorter duration of disintegration, what would be the extent of the said shorter duration of disintegration as also what would be the effect of the same on the treatment of a patient. Therefore, the Court concluded that the present patent application is nothing but an attempt to increase the term of the earlier patent for Tofogliflozin, which would not be permissible without a significant enhancement in therapeutic efficacy.


Based on the Novartis case and the recent Chugai Seiyaku case, it is concluded that the term “enhanced efficacy” in the context of pharmaceutical patent applications is applicable to “therapeutic efficacy” only. Any data that does not show the superior efficiency of new pharmaceutical drug or a new process of preparing the said drug over existing ones, in treating a patient, would not be considered as relevant data to overcome the hurdle of Section 3(d) of the Patents Act. Therefore, Section 3(d) of the Patents Act is not a hindrance for incremental innovations in the domain of pharmaceutical patent applications, provided such applications demonstrate the required data to surpass Section 3(d) of the Patents Act.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.