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Section 3 of the Act stipulates, “What are not inventions” as per the Act. The main aim of the amendments of the Patents (Amendment) Act of 2005 is to prohibit ever-greening of drug patents and bring within the ambit of patentability, the patents on variants of those chemical compounds that show significant enhancement in therapeutic efficacy.

Section 3(d) of the Act recites as follows:

“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”.

Thus, Section 3(d) of the Act stipulates that in an invention claiming an already known substance, having established medicinal activity, such substance shall be deemed to be treated as a same substance, and thus, shall fall foul of patentability, unless the invention is able to demonstrate significantly improved therapeutic efficacy with respect to that known compound.


Often misunderstood, Section 3(d) of the Act, does not in fact act as an impediment in the patentability of pharmaceutical inventions. The Supreme Court of India in a landmark judgement[1] in 2013, has emphasized on the positive construction of Section 3(d) in the patentability of pharmaceuticals as a second-tier of qualifying standards for pharmaceutical products in order to leave the door open for true and genuine inventions, but at the same time, to check any attempt at repetitive patenting or extension of the patent term on spurious grounds.

The provision of Section 3(d) of the Act is adjudicated meticulously and with utmost care by the IPO. To enable Applicants to substantiate the therapeutic efficacy of their invention, in various matters, Controllers have permitted the Applicants to produce additional data and experimental results during the proceedings, even in cases where said data and results were not directly referenced in the specification of the application.









































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