Section 3(d) of the Patents Act: How India Stops Pharma Evergreening

Section 3(d) of the Patents Act, 1970 is a one-sentence provision that decides whether a pharmaceutical company can patent a tweaked version of an existing drug. It is short, technical, and one of the most-watched IP provisions in any emerging-economy patent statute. In 2013 the Indian Supreme Court read it strictly in Novartis AG v. Union of India and refused a patent for the beta-crystalline form of imatinib mesylate — the cancer drug Glivec. The ruling kept generic imatinib available at roughly a tenth of the branded price and set the tone for how India treats incremental pharma claims.

This guide covers what Section 3(d) actually says, what counts as a "new form" of a known substance, what "enhanced efficacy" means after Novartis, and why the provision matters for any company filing pharma or biotech claims in India.

The text of Section 3(d)

Section 3(d) declares the following not an invention within the meaning of the Patents Act:

"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."

An Explanation attached to the provision treats salts, esters, ethers, polymorphs, metabolites, isomers, mixtures of isomers and other derivatives of a known substance as the same substance unless they differ significantly in properties with regard to efficacy. This is the bar Indian pharma applicants meet at examination.

A new crystal form is not a new drug. The Patent Office wants better medicine, not better claim drafting.

What Novartis tried to patent — and why it failed

Novartis filed a patent in India on the beta-crystalline form of imatinib mesylate. The free-base imatinib was already known and disclosed in earlier filings. Novartis argued the beta-crystalline form was more stable, more easily processed and 30% more bioavailable in animal models. The Indian Patent Office rejected the claim. The Intellectual Property Appellate Board (IPAB) upheld the rejection. Novartis carried the matter to the Supreme Court.

The Supreme Court agreed with the rejection. The Court read Section 3(d) as requiring "therapeutic efficacy" — not just any property change. Better solubility, better stability and better flow are physicochemical improvements, useful for manufacturing but not the kind of efficacy the statute protects. Bioavailability data could be relevant, but Novartis did not produce in-human therapeutic-efficacy data showing the beta-crystalline form treated cancer better than the free-base form. The patent was refused. Novartis AG v. Union of India, (2013) 6 SCC 1.

How Indian examiners apply 3(d) today

Examiners now routinely raise Section 3(d) objections in pharma prosecution. The applicant's reply must do two things: identify the known substance the claimed compound is derived from, and put on record evidence of enhanced therapeutic efficacy. Common evidence types:

• Comparative clinical-pharmacology data — head-to-head efficacy versus the prior-art reference compound in the same indication
• Pharmacokinetic data with a therapeutic correlate — bioavailability alone is not enough; the applicant must connect the PK improvement to a better treatment outcome
• In-human efficacy data from at least Phase I or II studies where available, even if not granted-condition-specific
• Disease-model data where in-human data does not yet exist, with a reasoned scientific bridge

Beyond pharma: 3(d) for chemistry and biotech

Section 3(d) is written in general terms — "any substance" — and applies beyond pharmaceuticals. Crop-protection chemistry, food-grade additives and biotech preparations have all encountered 3(d) objections. The Patent Office reads "efficacy" in context: agrochemical efficacy for a herbicide, nutritional efficacy for a food additive, therapeutic efficacy for a medical biologic. The principle stays the same — incremental property changes do not pass; demonstrable enhanced performance does.

The competition-law dimension

Section 3(d) interacts directly with India's policy goal of keeping generic medicines accessible. After the Novartis ruling, several other pharma 3(d) refusals were upheld in similar fact patterns. Indian generics continue to enter the market on schedule once compound patents expire, instead of facing a wall of incremental polymorph and salt patents. This is the policy core of 3(d): a high bar at the patent gate, in service of public-health pricing.

What this means for applicants

Three practical takeaways for pharma and biotech filers in India:

• Choose your strongest molecule, not your most defensible polymorph. File the compound patent on the active moiety with real efficacy claims, not on a downstream form whose only advantage is processability.
• Front-load the efficacy file. The 3(d) reply window is short. Comparative data and prior-art mapping should sit in the file at filing, not be constructed under deadline.
• Plan Indian filings differently from US/EU strategy. An incremental polymorph that may pass in the USPTO will draw a 3(d) objection in Delhi. Adjust the claim scope accordingly.

For Indian innovators, the practical implication is opposite and useful: a robust efficacy package strengthens the patent against pre-grant opposition and post-grant revocation, both of which use 3(d) frequently. IPForte's patentability search includes a Section 3(d) screen on every pharma and chemistry claim; office-action handling on 3(d) is one of the most common matters we run.

The takeaway

Section 3(d) is short, the case law is settled, and the answer is not legal drafting — it is data. The Indian Patent Office grants pharma patents every year, including on new forms of known substances, when the efficacy evidence is real. The Novartis line stops the patents where the evidence is not. For founders, generics and originator companies alike, that line is the most important sentence in Indian patent law to understand.