Section 3(d) of the Indian Patents Act: Pharmaceutical Patents and the Evergreening Bar
Section 3(d) of the Indian Patents Act 1970 limits patents on new forms of a known substance, the courts having read the relevant enhancement in the pharmaceutical context as therapeutic efficacy. Aimed at preventing evergreening, it raises the bar for incremental pharmaceutical inventions. Assessment is fact-heavy and jurisdiction-specific, so confirm current law with the Indian Patent Office or local counsel.
Section 3(d) is one of the most consequential provisions in Indian patent law for any pharmaceutical or life-sciences business, and it is the single rule that most often surprises applicants who arrive from systems that grant patents more readily on incremental chemical inventions. It sits within Section 3 of the Patents Act 1970, the section that lists what is "not an invention" and therefore not patentable in India. Section 3(d) targets a specific commercial pattern, the practice of seeking fresh patent protection for new forms, derivatives or minor variants of substances that are already known. This page explains, at a general level, what the provision does, the role it played in the well-known Novartis Glivec decision, and how it shapes filing strategy in practice. It is general information, not legal advice, and because Section 3(d) assessments turn heavily on the facts of each case, the sensible course before relying on any patent position in India is to consult a vetted local firm.
What Section 3(d) actually says and does
In broad terms, Section 3(d) treats as not patentable 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. The same logic extends to the mere discovery of a new property or new use for a known substance, and to the mere use of a known process, machine or apparatus, unless that known process results in a new product or employs at least one new reactant. The provision then carries an Explanation that, for the purposes of the section, treats salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives of a known substance as the same substance, unless they differ significantly in properties with regard to efficacy.
It is worth being precise about the wording rather than collapsing it into a single test. The main provision turns on whether there is an enhancement of the known efficacy of the substance. The Explanation operates separately, deeming the listed derivatives the same substance unless they differ significantly in properties with regard to efficacy. The courts have read efficacy in the pharmaceutical context as therapeutic efficacy (discussed below), but the precise interaction between the main clause and the Explanation is itself a fact-specific question that has been worked out through litigation rather than settled by a tidy formula. The paraphrase above is for orientation only; the operative text is Section 3(d) and its Explanation, which should be read in full as currently in force through the Indian Patent Office's official channels and applied with local counsel.
The practical effect is a heightened threshold for a defined category of pharmaceutical and chemical inventions. If your invention is a new salt, polymorph, isomer or other derivative of a compound that is already known, Section 3(d) does not automatically refuse it, but it does engage this efficacy-related enquiry. Absent a sufficient showing, the new form risks being treated as the same substance and falling outside patentability. This is distinct from the general requirements of novelty, inventive step and industrial application that every patent must satisfy; Section 3(d) is an additional, subject-matter-specific filter that applies even where a derivative might otherwise look novel and inventive on paper.
It is worth being precise about scope. Section 3(d) does not bar pharmaceutical patents as a class, and it does not prevent patents on genuinely new compounds or new molecular entities. It bites on incremental variations of substances already in the public domain. A first-in-class new chemical entity is not what the provision is aimed at; the provision is aimed at the layering of follow-on protection onto substances whose underlying patent or knowledge already exists.
The evergreening rationale
The policy behind Section 3(d) is the prevention of what is commonly called evergreening, the strategy of extending the effective period of exclusivity around a medicine by obtaining sequential patents on minor modifications as the original protection nears expiry. The concern animating the provision is that a series of incremental patents, each on a new salt, polymorph or formulation, can keep generic competition out of the market well beyond the life of the patent on the original active substance, with downstream effects on the price and availability of medicines.
India reintroduced pharmaceutical product patents through a 2005 amendment to its patent law, as part of aligning with its obligations under the TRIPS agreement, and Section 3(d) was amended around the same time; you should confirm the current statutory wording and its history with the Indian Patent Office or local counsel rather than relying on this summary. The broad legislative choice was to permit pharmaceutical product patents while building in a guard against the specific risk that incremental patenting could undermine access to affordable medicines. Whether one regards the provision as a sensible access safeguard or as an unusually demanding hurdle, the underlying intent is reasonably settled: Section 3(d) is an access-and-competition policy expressed through patentability criteria, and it should be read in that light rather than as a mere technical formality.
The Novartis Glivec context
Section 3(d) became internationally known through litigation concerning the cancer medicine imatinib, marketed by Novartis as Glivec (also spelled Gleevec in some markets). What follows is the reading the Supreme Court of India gave in that specific case; treat it as the anchoring authority on the meaning of the efficacy requirement rather than as a codified, universal rule, because its application remains fact-specific and has continued to develop. The application at issue concerned the beta crystalline form of imatinib mesylate, a particular polymorphic form, rather than a bare salt as such. That claimed form was refused by reference to Section 3(d), the matter was litigated through the Indian system, and it ultimately reached the Supreme Court of India, which delivered a much-cited decision upholding the refusal.
The significance of the decision, for present purposes, lies in how the court read the efficacy requirement rather than in the specific outcome on one molecule. The court indicated that, in the pharmaceutical context, the relevant enhancement is generally understood as therapeutic efficacy, and that improvements in properties such as stability, solubility or other physico-chemical characteristics will not on their own suffice unless they are tied to a demonstrated improvement in therapeutic effect. The court did not frame this as a blanket exclusion of all physico-chemical properties in every case; the point was that such improvements do not satisfy the test by themselves, divorced from therapeutic effect. The judgment is generally read as confirming that Section 3(d) sets a real, substantive bar rather than a presumption that can be met by reformulation alone.
I would flag that the precise contours of how therapeutic efficacy is applied continue to be worked out across subsequent matters and can turn on the technology and the evidence put forward. The headline reading above is widely accepted, but the application to any given invention is fact-specific, and the body of decisions interpreting Section 3(d) keeps developing. Treat the Glivec decision as the anchoring authority on the meaning of the efficacy requirement, and treat its application to your facts as a question for qualified local counsel.
Practical effect on pharmaceutical and life-sciences filing strategy
For anyone planning to file in India, Section 3(d) is not a peripheral consideration; it should sit at the centre of the patentability analysis for any invention that could be characterised as a new form of a known substance. The most important consequence is evidential. Where your invention is a salt, polymorph, isomer, metabolite, formulation or other derivative, you should expect to need data going to enhanced therapeutic efficacy relative to the known substance, and that data ideally needs to be available and articulated at the time of filing rather than assembled after an objection lands. Comparative data that speaks only to improved stability, manufacturability or solubility, without a bridge to therapeutic effect, is unlikely to carry the argument on its own.
A second consequence is the framing of the specification. The way a claimed invention is described, and the comparison it draws against the closest known substance, can materially affect how Section 3(d) is assessed. A specification that candidly identifies the known substance and presents efficacy data against it stands on firmer ground than one that obscures the relationship. Because India also imposes distinctive disclosure duties on applicants more generally, the drafting choices here interact with broader prosecution obligations, which reinforces the case for local input early.
The table below sketches, at a high level, how different invention types tend to interact with the provision. It is a simplification for orientation only, not a substitute for an assessment of your facts.
| Type of invention | Typical Section 3(d) exposure |
|---|---|
| New chemical entity (first disclosure of the compound) | Generally outside the core target of Section 3(d), assessed on ordinary criteria |
| New salt, polymorph or isomer of a known compound | High exposure; usually engages the efficacy enquiry and an enhanced therapeutic efficacy showing |
| New formulation or combination of known substances | Often within scope; an efficacy showing is typically expected |
| New use or new property of a known substance | Mere discovery of new use or property generally not patentable as such |
A third consequence is portfolio strategy. Businesses that rely heavily on lifecycle management through follow-on filings in other markets should not assume the same playbook will transfer to India. A patent family that succeeds elsewhere on a polymorph or salt may meet a different reception in India, and the realistic strength of any Indian member of that family should be evaluated on its own footing. Cost should be thought of in terms of the drivers, the number and complexity of filings, the evidence and expert input a Section 3(d) argument may require, and the prosecution it invites, rather than any fixed figure; confirm current official fees on the Indian Patent Office's website. For the surrounding mechanics of how applications are filed and examined in India, see our overview of patents in India and the practical walkthrough of how to file a patent in India. Where you are reaching India through an international application, the route in is covered in our note on the PCT.
Why this is jurisdiction-specific and fact-heavy
Section 3(d) is a feature of Indian law and should not be assumed to mirror the position in any other jurisdiction. Many patent systems will grant protection on new forms of known substances on ordinary novelty and inventive-step criteria, without an additional efficacy gate of this kind. The existence of the provision, the way the efficacy requirement has been read in the pharmaceutical context, and the body of decisions applying it are particular to India. Applicants who reason by analogy from their home system are precisely the applicants most likely to be caught out.
Equally, the provision is not mechanical. Whether a given new form clears Section 3(d) depends on what the known substance is, what is already in the public domain, the nature of the modification, and above all the quality and relevance of the efficacy evidence. Two superficially similar polymorph applications can fare differently depending on the data behind them. This is why a general guide can describe the shape of the rule but cannot tell you how it will apply to your molecule. The current statutory wording, the prevailing judicial interpretation, and the office's examination practice are also subject to development over time, so any specific position should be confirmed against the current law rather than against a summary like this one.
A few related points are worth holding in view alongside Section 3(d), without overstating them here. India's broader subject-matter exclusions, its applicant disclosure duties, and its pre- and post-grant opposition mechanisms can all interact with a pharmaceutical filing, and a Section 3(d) issue rarely arises in isolation. The interplay between these features is part of why Indian pharmaceutical prosecution rewards local expertise.
A note on getting this right
Section 3(d) rewards preparation and punishes assumption. If you are filing on anything that could be read as a new form of a known substance, the questions to settle early are what the closest known substance is, what therapeutic-efficacy comparison you can credibly make, and how the specification should present that comparison. Those questions are best answered before filing, when you still have room to gather data and shape the application, rather than after an examination objection has framed the debate.
This article is general information and not legal or regulated advice. IPEnvoy is not a law firm and does not conduct reserved or regulated legal work; it provides general information and connects businesses with vetted local IP firms. The wording of Section 3(d) and its Explanation, their interpretation by the Indian courts, and the examination practice of the Indian Patent Office under the Patents Act 1970 are subject to change and turn on the facts of each case. Before relying on any patent position in India, confirm the current law and apply it to your specific facts with qualified local counsel, and verify current requirements and fees through the Indian Patent Office's official channels.