Introduction

Sufficiency of disclosure is a core requirement in patent law, ensuring that an invention is described in a manner that allows a person skilled in the art to perform it. In return for the limited monopoly granted by a patent, the inventor must disclose the invention clearly, enabling public use once the patent expires. The disclosure must strike a balance: it should be detailed enough to teach the invention, but not so broad or vague as to obscure how it works.

Sufficiency of Disclosure in Indian Patent Law

In India, this requirement is enshrined under Section 10(4) of the Indian Patents Act, 1970 (“Act”)  which mandates that every complete specification shall:

1. fully and particularly describe the invention and its operation or use and the method by which it is to be performed;
2. disclose the best method of performing the invention which is known to the applicant and for which he is entitled to claim protection; and
3. end with a claim or claims defining the scope of the invention for which protection is claimed;
4. be accompanied by an abstract to provide technical information on the invention.”

The enablement requirement under clause (a) and the “best mode” requirement under clause (b) ensure that the invention is disclosed clearly enough for a person skilled in the art to perform it. Thus, a complete specification being filed in the Indian Patent Office should comply with both enablement and best mode requirements as specified in the Act.

Examination Practice and Grounds for Refusal

In India, sufficiency of disclosure is not just a drafting formality but a frequent ground for objection in First Examination Reports (FERs) and patent refusals. Some recent examples illustrate this:

• In 201611017772, the Controller refused the application for failing to disclose how cultural attributes were evaluated, despite the invention claiming to determine cultural fitment for careers. The lack of technical details was found to violate Section 10(4).
• In 7795/DELNP/2007, multiple independent claims made it difficult to determine the scope of the invention. The purpose of the claimed apparatus was not mentioned in the preamble of the claims. Moreover, the absence of structural details in the claims, unsupported by the specification, led to a refusal for lack of clarity and insufficiency.

In addition, insufficiency of disclosure is also a statutory ground for pre-grant opposition [Section 25(1)(g)], post-grant opposition [Section 25(2)(g)], and revocation [Section 64(1)(h)] under the Patents Act. These provisions empower third parties to challenge patents that fail to meet the disclosure threshold.

Legal Precedents Emphasizing Sufficiency

Judicial and quasi-judicial bodies have reiterated the importance of sufficient disclosure:

In Ram Narain Kher v. Ambassador Industries,¹ the Delhi High Court acknowledged that inadequate disclosure could justify revocation.

In the case of Tata Global Beverages Limited vs Hindustan Unilever Limited², the erstwhile Intellectual Property Appellate Board (IPAB) held that the sufficiency requirement is satisfied even when at least one way of working the invention is clearly described, enabling a skilled person to carry out the invention. It also ruled that Section 10(4) does not necessitate disclosing all conceivable ways of operating the invention but only mandates disclosure of the best method known to the applicant.

In the matter of Titan Umreifungstechnik GMBH and Co. KG v. Assistant Controller of Patents and Designs³, Delhi High Court stated “primary requirement is that the application includes a clear and complete description of the invention, its operation, use and method by which it is performed so that a person skilled in the relevant field can reproduce the invention based on the description in the application”. The Court also pointed out that the working example requirement differs for chemical and non-chemical inventions and made it clear that there is no mandatory requirement to provide examples for non-chemical related inventions.

In Diamcad N.V v. Asistant Controller of Patents & Designs,⁴ IPAB refused a claim amendment where the new claims were not fairly supported by the original description, violating sufficiency requirements.

In AstraZeneca AB & Anr. v. Emcure Pharmaceuticals Ltd.,⁵ the court reiterated that lack of enablement and best mode could impact the enforceability of pharma patents. Similarly, in F. Hoffmann-La Roche Ltd. v. Cipla Ltd.,⁶ the court emphasized the importance of disclosing the best method of performing the invention and how a lack of such disclosure could lead to patent invalidation. Bayer Corporation v. Union of India⁷ held that a patent specification must contain enough information and data so that a person skilled in the art can make and use the invention 

In the case of FDC v. Sanjeev Khandelwal, the Madras High Court held that while the best method must be submitted, claims need not be representative of the best method .

Most recently, in The Regents of the University of California v. The Controller of Patents,⁸ the Delhi High Court upheld the refusal of a patent, highlighting that Section 10(4) requires a complete specification to “particularly describe the invention and the manner in which it is to be performed.” The Court agreed with the Controller’s assessment that the claims were not sufficiently supported by the description, leading to a lack of enablement.

Comparative Analysis: India, US, and Europe

In the United States, the enablement and best mode requirements are set out under 35 U.S.C. §112(a). The statute mandates that the specification must contain a written description of the invention and the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to make and use the invention. Courts in the U.S. have clarified that the enablement requirement is not satisfied unless the invention can be practiced without undue experimentation. The best mode requirement is still part of the statutory text, though post-AIA, failure to disclose best mode is no longer a basis for invalidity.

In the European Patent Convention (EPC) framework, Article 83 EPC mandates that the application disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. This is closely tied to Rule 42(1)(e) and Article 84 EPC, which require that claims must be supported by the description. The EPO consistently enforces sufficiency, particularly where broad claims are not accompanied by adequate experimental data or examples.

Compared to India, both jurisdictions adopt similar principles of enablement but differ in procedural handling. For example, while India includes the best mode requirement explicitly and treats it as a revocation ground under Section 64(1)(h), the U.S. has de-emphasized best mode enforcement, and the EPC does not have a corresponding standalone requirement. Thus, Indian practice reflects a blend of common law interpretation and statutory rigor, positioning sufficiency of disclosure as both a grant and post-grant safeguard.

Conclusion

The requirement of disclosing the invention sufficiently in the patent specification, which should enable a person with average skill and knowledge of the art to be able to replicate the invention to get the claimed results, is a statutory requirement which is as important as novelty, inventive step and industrial capability requirements for the grant of a patent. Including working examples, diagrams, flowcharts, or illustrations can significantly enhance the clarity of a patent application.

1. A.I.R. 1976 Delhi 87 ↩︎
2. TRA/1/2007/PT/MUM ↩︎
3. C.A.(COMM.IPD-PAT) 114/2022 ↩︎
4. Order No. 189/2012 ↩︎
5. CS(COMM) 561/2019 ↩︎
6. RFA(OS) 92/2012 ↩︎
7. W.P..1323 OF 2013 ↩︎
8. 2025 SCC OnLine Del 987 ↩︎