There’s a common surprise that hits first-time patent applicants in India. You can have an idea that’s genuinely new, inventive, and completely usable in industry… and still be refused a patent. It’s not because the examiner dislikes you, and it’s not even about the three main patentability tests. It’s because India has a set of statutory “gatekeepers” in Sections 3 and 4 of the Patents Act. These provisions don’t care how clever your idea is, if it fits into one of their categories, it’s excluded from patent protection altogether.
This isn’t a flaw in the system; it’s deliberate. The law aims to protect true technological contributions while keeping certain kinds of subject matter free for everyone to use. Some of the exclusions are obvious, like inventions that defy natural laws. Others are subtle and have been shaped by years of litigation. If you’ve ever wondered why a particular claim was struck down, chances are you’ll find the reason in one of these sections.
Let’s walk through them… slowly, clearly, and with real-world context, so the next time you’re thinking about filing a patent application, you’ll know exactly which traps to avoid and where there might still be a path forward.
The Legal Foundation
Before we attempt to understand the exclusions, it’s worth understanding where they sit in the bigger picture. Section 2(1)(j) of the Patents Act defines an “invention” as something novel, involving an inventive step, and capable of industrial application. That’s the front door. But once you step inside, Sections 3 and 4 start striking out whole classes of things that simply aren’t considered patentable subject matter in India, no matter how well they might pass those other tests.
Section 3(a): Inventions That Are Frivolous or Contrary to Natural Laws
This is where the so-called perpetual motion machines meet their end. If your invention claims to produce unlimited energy from nothing, reverse gravity without any scientific basis, or achieve chemical reactions that contradict established laws of nature, it’s not patentable. The Indian Patent Office doesn’t just reject these on principle, it’s a matter of scientific integrity. Claims need to be backed by demonstrable, reproducible results, not wishful thinking.
Section 3(b): Inventions Contrary to Public Order or Morality
The law also shuts the door on anything whose use would be contrary to public order, morality, or that could seriously harm human, animal, or plant life, or the environment. Weapons of mass destruction, dangerous bio-agents without controls, or technologies designed for illegal surveillance fall squarely here. This clause is not used lightly, but when invoked, it’s absolute.
Section 3(c): Mere Discovery of a Scientific Principle or Natural Substance
Finding something that already exists in nature isn’t enough for patenting it. If you discover a new mineral or identify a naturally occurring DNA sequence, you’ve made a scientific contribution, but not a patentable invention (invention defined under patents law 1970). To cross the threshold, you need to apply that discovery in a way that results in a novel and useful product or process.
Section 3(d): New Forms of Known Substances Without Enhanced Efficacy
Pharmaceutical companies know this one by heart, thanks to Novartis v. Union of India. The Supreme Court held that for medicines, “efficacy” in this section means therapeutic efficacy. Simply improving properties like solubility or stability isn’t enough unless it translates into an actual therapeutic benefit for patients. This is meant to prevent “evergreening”, stretching out patent monopolies with minor, non-therapeutic tweaks.
Section 3(e): Mere Admixture of Substances
Mixing two known substances, each performing their own function as before, isn’t an invention. The Patent Office will ask: does the combination produce a new or improved result beyond the sum of its parts? If you can show true synergy, for example, a blend of two chemicals that together kill bacteria more effectively than either alone, then you might escape this exclusion.
Section 3(f): Mere Arrangement or Duplication of Known Devices
If your “new” system is just a bunch of known devices stuck together, each doing exactly what it always did, this clause will apply. To be patentable, the arrangement has to create a co-operative technical effect, maybe it makes the system faster, more energy-efficient, or more accurate in ways the individual parts couldn’t achieve alone.
Section 3(h): Methods of Agriculture or Horticulture
The law leaves traditional cultivation methods out of the patent system. You can’t patent a new way of pruning plants or rotating crops. But that doesn’t mean agricultural innovation is off the table entirely… new tools, machines, or controlled-environment systems might be patentable if claimed properly.
Section 3(i): Methods of Treatment or Diagnosis
Medical, surgical, therapeutic, and diagnostic methods performed on humans or animals are excluded. This protects the freedom of medical practitioners to use such methods without fear of infringement. But devices and in-vitro testing systems can still be patentable. Recent court discussions have drawn fine lines here: measuring something in a lab may be allowed, but diagnosing a disease in a patient based on that measurement may still fall within the exclusion.
Section 3(j): Plants, Animals, and Essentially Biological Processes
Except for microorganisms, living organisms are off-limits. The Monsanto v. Nuziveedu case cemented that genetically modified traits in seeds aren’t patentable in India. This doesn’t mean all biotech is blocked, microbiological processes and innovations involving microorganisms can still be eligible.
Section 3(k): Mathematical and Business Methods, Computer Programs Per Se
This is the software clause. Mathematical algorithms and business processes on their own aren’t patentable, and neither are computer programs “per se.” But the “per se” language has been interpreted to allow patents where a computer program is tied to a novel hardware implementation or produces a concrete technical effect. Ferid Allani v. Union of India was a turning point, with the Delhi High Court emphasising that genuine technical advancements shouldn’t be dismissed simply because they involve software.
Section 3(l) - 3(o): Aesthetic Creations, Mental Acts, Game Rules, Presentations of Information, IC Topographies
These categories are better protected through other forms of intellectual property. Aesthetic designs may qualify for design registration, rules for games can be published and copyrighted, and presentations of information might be protected by copyright or database rights.
Section 3(p): Traditional Knowledge
If your invention is based on knowledge that’s already part of the public domain in India, especially traditional knowledge documented in texts or the Traditional Knowledge Digital Library, it can’t be patented. Using turmeric for healing or neem for pest control are classic examples. You’ll need to demonstrate a truly novel application or modification to get around this exclusion.
Section 4: Atomic Energy
Any invention related to atomic energy is excluded unless it has clearance from the Department of Atomic Energy. This is a narrow but absolute restriction.
Navigating the Borderline Cases
Many real-world inventions sit uncomfortably close to these exclusions. Artificial intelligence and machine learning models often face Section 3(k) objections unless they’re integrated into a system with measurable technical benefits. Diagnostic technologies risk falling under Section 3(i) unless they’re claimed as devices or processes that don’t directly involve treatment.
Pharmaceutical polymorphs and salts are vulnerable under Section 3(d) without solid therapeutic efficacy data.
These “borderline” scenarios aren’t hopeless. They require careful claim drafting and, often, strategic evidence gathering before filing. A technical effect study, clinical trial data, or performance benchmark can be the difference between rejection and acceptance.
The smartest way to beat these exclusions is to avoid posing them they are in the first place. That means describing the invention in enough technical detail that it’s clearly outside the excluded category, and supplying evidence in the specification where possible. For software, emphasise hardware integration and measurable improvements in performance. For pharmaceuticals, include therapeutic efficacy data up front. For mixtures, show synergy with experimental results.
When a Patent Isn’t the Right Fit
If your idea truly falls into an excluded category, other IP routes may still protect it. Design registration can safeguard visual features of a product. Copyright can protect source code or graphical interfaces. Plant variety protection laws can cover new plant breeds. Trade secrets can secure processes that can’t be patented. Knowing these alternatives ensures you don’t waste time and resources chasing an ungrantable patent.
Learning from the Cases
The exclusions aren’t just theoretical; they’ve been shaped by court decisions. Novartis showed how high the bar is for pharmaceuticals under Section 3(d). Ferid Allani demonstrated that technical effect can open a door under Section 3(k). Dimminaco A.G. v. Controller confirmed that processes producing living organisms can be patentable. Monsanto made clear the boundaries of 3(j) in agricultural biotech. Each case is a lesson in both the limits of the law and the creativity needed to work within it.
Seeing the Guardrails, Not Just the Walls
Sections 3 and 4 often get a bad rap as roadblocks, but they’re really more like signposts on a winding road. They’re not just there to say “stop”, they’re pointing you toward a better route. If you know where these exclusions sit and why they’re there, you can steer your R&D in the right direction, shape your claims with purpose, and line up the kind of evidence that makes the Patent Office nod instead of frown.
So when you ask, “Which inventions are not patentable in India?” don’t think of it as an innovation killer. Think of it as a quiet nudge to invent and file with more intent, to make intellectual property part of your creative journey right from the start, not an afterthought at the finish line.
Author: Abhijit Bhand
Abhijit is an Intellectual Property Consultant and Co-founder of the Kanadlab Institute of Intellectual Property & Research. As a Registered Indian Patent Agent (IN/PA-5945), he works closely with innovators, startups, universities, and businesses to protect and commercialize their inventions. A double international master’s degree holder in IP & Technology Law (JU, Poland), and IP & Development Policy (KDI School, S. Korea), and a Scholar of World Intellectual Property Organisation (Switzerland), Abhijit has engaged with stakeholders in 15+ countries and delivered over 300 invited talks, including at FICCI, ICAR, IITs, and TEDx. He is passionate about making patents a powerful tool for innovation and impact.
