The invention is new - and still not patentable

What section 3 actually does

Section 3 does not ask whether anyone has done it before. It asks what kind of thing it is. If the answer is a mathematical or business method, a computer programme per se, an algorithm, a method of treatment of humans or animals, a mere discovery of something occurring in nature, a mere admixture, a mere rearrangement of known devices, a method of agriculture or horticulture, a presentation of information, an aesthetic creation, or several other listed categories, it is simply outside the system.

Section 4 historically barred inventions relating to atomic energy outright; that position was changed by the SHANTI Act, 2025, which amended section 4 so that nuclear-energy inventions are no longer excluded as a class - though government-reserved activities remain restricted. There is no argument about novelty that fixes a section 3 problem, because novelty was never the question.

Where it bites hardest

Three clauses account for most refusals in practice. Section 3(d) catches new forms of known substances that do not show enhanced efficacy, and is a second gate for pharmaceutical and chemical inventions on top of novelty and inventive step. Section 3(k) catches software and business methods, though the case law is more nuanced than the reputation suggests. Section 3(i) catches methods of medical treatment, including diagnostic and therapeutic methods - though products used in treatment remain patentable.

The practical response is almost always about claim category and framing, not about arguing that the exclusion should not apply. A method of treatment may become a claim to a device or a composition. A software method may become a claim to a system delivering a specific technical effect.