The claim category is central
Section 3(i) of the Patents Act excludes processes for medicinal, surgical, curative, prophylactic, diagnostic, therapeutic or other treatment of human beings, as well as specified treatment of animals. A claim to a treatment or diagnostic process should be distinguished from a claim to a product, composition, kit, instrument or equipment. The intended use of a product matters to claim construction, but it does not automatically turn every product claim into a method claim.
Recent diagnostic decision: Natera
In Natera Inc. v. Assistant Controller of Patents and Designs (Delhi High Court, 9 October 2025, C.A.(COMM.IPD-PAT) 16/2023), the Court considered claims directed to detecting lung cancer using cell-free tumour DNA from a blood sample. It concluded that, read with the specification, the claimed process was directed to diagnosing and determining lung cancer and was excluded under Section 3(i). The decision is an important warning that laboratory processing or an ex-vivo sample does not by itself take a claim outside the diagnostic-method analysis when the claimed process is directed to a diagnostic conclusion.
The judgment also distinguished process claims from products used for diagnosis or therapy, such as kits, equipment and physical products, which may be assessed for patentability under the ordinary statutory conditions. The actual claims and the endpoint of the process remain decisive.
Recent product-claim decision: Medilabo
In Medilabo RFP Inc. v. Controller of Patents (Delhi High Court, 24 November 2025, C.A.(COMM.IPD-PAT) 16/2024), the Court examined whether a claimed composition was really a treatment method. It emphasised reading the claims, description and record together, and distinguished a defined composition from a process performed by a medical professional. The application was sent back for a fresh decision and hearing; the Court did not itself grant a patent. The case illustrates why a claim should be classified by its substance, not by a single phrase in its preamble or by the fact that the product has a therapeutic purpose.
Questions to ask when preparing claims
- Does the claim require a practitioner or another person to perform a sequence of diagnostic or treatment steps?
- Does the claimed process itself reach a diagnosis or prescribe or perform treatment, or does it generate an intermediate measurement or technical output?
- Is the claim actually to a composition, device, kit or instrument, with the treatment context appearing only as intended use?
- Do the claims match the disclosure and examples, and are any amendments supported by the application as filed?
These questions do not replace the statutory analysis. In Natera, the Court did not treat foreign patent grants as determinative of Indian eligibility. A diagnostic, pharmaceutical or medical-device application still requires separate analysis of novelty, inventive step, sufficiency, claim scope and every relevant Section 3 exclusion.
Keep the specification aligned
For medical and diagnostic technologies, describe the technical contribution, the role of any clinician, the sample or measurement being analysed, the steps that produce an output and the product features that implement the method. Draft product claims and method claims with their distinct scope in mind, and do not rely on a later amendment to supply disclosure that was absent at filing.
This article is a general overview, checked on 10 October 2026. Section 3(i) is fact-sensitive; claim wording and the complete specification must be reviewed together.