Patent evergreening is a strategy used primarily in the pharmaceutical industry to extend the market exclusivity of a drug beyond the original 20-year patent term. It involves filing new patents on minor modifications of the original compound — such as a new salt form, polymorph, isomer, metabolite or delivery mechanism — without any significant improvement in therapeutic efficacy.
The economic motivation is straightforward: once a patent expires, generic manufacturers can produce the same drug at a fraction of the price. By evergreening — stacking multiple patents around the same active ingredient — a company can effectively block generics from entering the market for years beyond the original patent period.
💡 Why it matters in India: India is the "pharmacy of the world", supplying 60% of global vaccines and affordable generics. Evergreening can price life-saving medicines out of reach for millions of patients — which is why India's law takes a strict position against it.
Section 3(d) of the Patents Act: India's Unique Defence
India's Patents Act 1970, Section 3(d) bars patents for new forms of known substances unless the applicant proves that the new form shows significantly enhanced efficacy compared to the original. In plain language: a new salt, polymorph, ester or other derivative of an existing drug is not patentable in India unless it works meaningfully better.
Merely showing better solubility or bioavailability is not enough — there must be a genuine therapeutic improvement. This provision was deliberately inserted into the Patents (Amendment) Act 2005 to prevent pharmaceutical evergreening while complying with India's TRIPS obligations.
Novartis v Union of India (2013): The Landmark Ruling
The most significant test of Section 3(d) came in the Supreme Court of India's landmark judgment in Novartis AG v Union of India (2013). Novartis sought a patent for Glivec (imatinib mesylate), a breakthrough drug for chronic myeloid leukaemia, claiming that the beta crystalline form of the compound was a new and patentable invention.
The Supreme Court rejected the patent application, holding that the beta crystalline form was a new form of a known substance and that Novartis had not demonstrated enhanced therapeutic efficacy — only improved bioavailability, which the Court held was insufficient under Section 3(d). The ruling confirmed that India would not allow the patent system to be used to block access to affordable medicines.
Other Notable Evergreening Cases in India
- Sorafenib (Bayer) — India's first compulsory licence was granted in 2012 for this cancer drug on grounds of affordability and lack of domestic working of the patent.
- Tenofovir (Gilead) — Patent applications for this HIV medication were challenged by patient groups citing Section 3(d) and prior art, resulting in denial or withdrawal.
- Erlotinib (Roche/Genentech) — Patent for this cancer drug was challenged successfully at the Intellectual Property Appellate Board.
Compulsory Licensing: The Complementary Tool
Even where a pharmaceutical patent is validly granted, India's Patents Act provides for compulsory licensing under Sections 84–92 when: the drug is unaffordable to the public, the reasonable requirements of the public are not being satisfied, or the patented invention is not being worked in India. The generic manufacturer must pay a royalty to the patent holder, determined by the Controller of Patents.
Practical Implications for Businesses Filing Patents in India
If you are a pharmaceutical company or biotech startup seeking patent protection in India, Section 3(d) has direct implications for your filing strategy:
- Efficacy data is essential — If your application involves a new form of a known compound, you must include clinical or pharmacological data demonstrating significantly enhanced therapeutic efficacy over the original compound.
- Prior art searches are critical — Before filing, identify whether your compound or a related one already exists in the prior art. If it does, Section 3(d) will apply.
- Formulation patents face scrutiny — New drug delivery systems, dosage forms and coatings are subject to Section 3(d) if based on a known active ingredient.
- Process patents remain available — A genuinely novel manufacturing process for a known compound can still be patented in India, even where the compound itself is not.
For guidance on pharmaceutical patent strategy in India, speak with our patent team →
Questions About Pharmaceutical Patents in India?
Adv. Nikhil Soni advises pharmaceutical companies, biotech startups and innovators on patent strategy, Section 3(d) compliance and compulsory licensing in India.