Economic, Commercial and Intellectual Property Laws · Law relating to Patents

Inventions Not Patentable under Sections 3 and 4 of the Patents Act

Updated 11 October 2026 · Fact-checked

Section 3 of the Patents Act, 1970 lists things that are not inventions, such as mere discoveries, abstract theories, mere admixtures, methods of agriculture, medical treatment processes, business methods and computer programmes per se. Section 4 bars patents for inventions relating to atomic energy. To answer, match the facts to the clause, then conclude.

Understand Inventions Not Patentable (Sections 3 and 4)

A patent is granted only for an "invention". The Act does not just define what an invention is. It also lists, in section 3, subject matter that is not an invention. If your facts fall in that list, no patent can be granted, however new or useful the thing is.

Think of section 3 as a filter with three kinds of exclusions. First, ideas and discoveries: abstract theories, scientific principles, things found in nature, and mere new uses of known things. Second, things that add nothing real: mere admixtures, and mere arrangement or duplication of known devices. Third, policy exclusions: public order, morality, harm to life, health or the environment, methods of treatment, plants and animals, and traditional knowledge.

The word mere matters in many clauses. Section 3(c) excludes the *mere* discovery of a scientific principle. Section 3(e) excludes a substance obtained by *mere* admixture that only aggregates the properties of its components. Section 3(f) excludes *mere* arrangement, re-arrangement or duplication of known devices, each functioning independently in a known way. If there is a real technical effect or synergy, the exclusion may not apply.

Section 3(d) is the most tested clause. A new form of a known substance (salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives) is treated as the same substance unless it differs significantly in properties with regard to efficacy. So the new form must show enhanced efficacy over the known substance. A mere new property or new use of a known substance is also excluded. Use of a known process is excluded unless it results in a new product or employs at least one new reactant.

Section 4 is separate and absolute: no patent shall be granted for an invention relating to atomic energy falling within section 20(1) of the Atomic Energy Act, 1962. Related provisions show how the State protects such matters. Section 65 lets the Central Government direct revocation of a patent already granted for such an invention. Section 157A lets it withhold information and revoke patents in the interest of the security of India.

Key rules to remember

Section 3(a) and 3(b): Frivolous or obviously contrary to natural laws = not an invention; primary or intended use contrary to public order or morality, or seriously prejudicial to human, animal or plant life or health or the environment = not an invention; Test the intended use or commercial exploitation, not just the product.
Section 3(c): Mere discovery of a scientific principle, abstract theory, or discovery of any living or non-living substance occurring in nature = not an invention; Discovering something already in nature is not inventing it.
Section 3(d): New form of known substance + no enhanced known efficacy = not an invention; Derivatives are the same substance unless they differ significantly in properties with regard to efficacy. Mere new use or new property is also excluded. A known process is excluded unless it gives a new product or uses at least one new reactant.
Section 3(e) and 3(f): Mere admixture (aggregation of properties) = not an invention; mere arrangement, re-arrangement or duplication of known devices working independently in a known way = not an invention; Look for whether the parts work together to give a new combined effect.
Section 3(h), (i), (j): Method of agriculture or horticulture; treatment processes for humans or animals; plants and animals in whole or part (other than micro-organisms), including seeds, varieties, species and essentially biological processes = not inventions; Micro-organisms are not excluded by clause (j).
Section 3(k) to (p): Mathematical or business method, computer programme per se, algorithms; literary, dramatic, musical, artistic works; mere scheme, rule or method of mental act or playing a game; presentation of information; topography of integrated circuits; traditional knowledge or aggregation or duplication of known properties of traditionally known components = not inventions; Remember the words per se in clause (k).
Section 4: Invention relating to atomic energy under section 20(1), Atomic Energy Act, 1962 = no patent; Section 65 allows revocation after grant; section 157A protects the security of India.

How to solve Inventions Not Patentable (Sections 3 and 4) questions

Use this method for any problem asking whether something can be patented.

1Identify the subject matter of the claimed invention in one line.
2Check section 4 first: does it relate to atomic energy under section 20(1) of the Atomic Energy Act, 1962? If yes, no patent.
3Scan section 3 clause by clause and pick the clause that fits the facts (for example 3(d) for a new form of a known drug).
4Quote the key words of the clause, including qualifiers such as mere, per se, or unless.
5Apply the facts to those words. For 3(d), ask whether efficacy is enhanced; for 3(e), whether properties merely add up.
6Check if any exception saves the claim, such as a new product or new reactant in 3(d), or a technical effect beyond a programme per se.
7Write a clear conclusion: patentable or not, citing the section and clause.
8If relevant, add that other conditions such as novelty and inventive step must still be met.

Quickest way: Clause-matching shortcut

When to use it: When you have under ten minutes for a short-note or scenario question.

Label the facts with one keyword: discovery, admixture, new form, method of treatment, software, atomic energy.
Match the keyword to its clause: discovery 3(c), new form 3(d), admixture 3(e), arrangement 3(f), treatment 3(i), software 3(k).
Write the clause in your own words with its qualifier.
Apply it to the facts in two lines.
Close with the conclusion and the section number.

Common mistakes in Inventions Not Patentable (Sections 3 and 4)

Saying a new form of a known drug is patentable because it is new.
Students look only at novelty and ignore the efficacy test in section 3(d).
Fix: State that derivatives are the same substance unless they differ significantly in properties with regard to efficacy. Then test the facts.
Saying all computer programmes are unpatentable.
Students drop the words per se in section 3(k).
Fix: Write "computer programme per se". The exclusion does not automatically cover everything involving software.
Treating section 4 as part of section 3.
Both are about non-patentable subject matter, so they get merged.
Fix: Cite them separately. Section 4 is a standalone bar for atomic energy inventions under section 20(1) of the Atomic Energy Act, 1962.
Excluding micro-organisms under section 3(j).
Students remember that plants and animals are excluded and over-extend it.
Fix: Remember the words other than micro-organisms. Micro-organisms are not excluded by that clause.
Citing section 3(g) or section 5 as current law.
Old notes and books list them.
Fix: Clause (g) of section 3 was omitted and section 5 was omitted by the 2005 Amendment. Do not cite them as operative.
Applying the admixture exclusion to every combination.
Students skip the word mere and the aggregation test.
Fix: The exclusion applies only where the result is merely an aggregation of the components' properties. A combination giving a new combined effect is not caught by 3(e) on that basis.

Worked examples

Example 1

Pharma Co. in Hyderabad develops a new crystalline polymorph of a known anti-diabetic drug. Tests show no significant difference in therapeutic efficacy from the known drug. It applies for a patent. Advise whether the invention is patentable.

Show the solution

Provision: section 3(d) says the mere discovery of a new form of a known substance, which does not result in enhanced known efficacy of that substance, is not an invention.
The Explanation to section 3(d) treats polymorphs and other derivatives of a known substance as the same substance, unless they differ significantly in properties with regard to efficacy.
Facts: the polymorph is a new form of a known drug, and there is no significant difference in efficacy.
Therefore the polymorph is treated as the same substance and the claim is a mere new form.

Answer: The claim is not patentable because it is not an invention under section 3(d). It would have been different only if the polymorph showed significantly enhanced efficacy.

Example 2

Bharat Energy Ltd. files a patent application for a process relating to atomic energy that falls within section 20(1) of the Atomic Energy Act, 1962. A patent is granted by mistake. Can it be revoked?

Show the solution

Provision: section 4 provides that no patent shall be granted for an invention relating to atomic energy falling within section 20(1) of the Atomic Energy Act, 1962.
Facts: the invention falls in that category, so the grant was contrary to section 4.
Section 65 applies where the Central Government is satisfied that a patent is for such an invention. It may direct the Controller to revoke the patent.
The Controller must give notice to the patentee and persons with an interest entered in the register, and give them an opportunity of being heard, before revoking.
Under section 65(2), the Controller may instead allow the patentee to amend the complete specification as he considers necessary.

Answer: Yes. Section 4 barred the grant. Under section 65, the Central Government can direct the Controller to revoke the patent after notice and hearing, or the Controller may allow an amendment of the specification instead.

Exam tips

Learn section 3(d) with its Explanation. It is the most likely clause for a long answer.
Memorise clause letters with keywords, but cite section 3 plus the clause in your answer.
Write the qualifiers: mere, per se, unless, other than micro-organisms. Marks are often tied to them.
Link section 4 with sections 65 and 157A in a note on atomic energy and national security.
End each answer with a one-line conclusion citing the section.

Practice questions from Law relating to Patents

Inventions Not Patentable (Sections 3 and 4) in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

CS ProfessionalPatentable Subject Matter and Conditions

Inventions Not Patentable (Sections 3 and 4): frequently asked questions

What is section 3 of the Patents Act, 1970?

Section 3 lists what are not inventions under the Act. If a claim falls in any clause, no patent can be granted for it. The clauses cover discoveries, abstract theories, mere admixtures, treatment methods, plants and animals, business methods, software per se and more.

What does section 3(d) say in simple words?

A new form of a known substance is not an invention unless it shows enhanced known efficacy. Salts, esters, polymorphs, isomers and similar derivatives count as the same substance unless they differ significantly in properties with regard to efficacy. A mere new use is also excluded.

What does section 4 of the Patents Act say?

Section 4 says no patent shall be granted for an invention relating to atomic energy falling within section 20(1) of the Atomic Energy Act, 1962. It is a complete bar on grant for such inventions.

Are computer programmes patentable in India?

Section 3(k) excludes a mathematical or business method, a computer programme per se, and algorithms. The words per se are important, so write them exactly in your answer.

Is the invention that is excluded under section 3 also barred by section 4?

No. They are separate provisions. Section 3 defines what is not an invention, while section 4 bars patents for atomic energy inventions under section 20(1) of the Atomic Energy Act, 1962.