The conservative approach of the Indian Patent Office in refusing the diagnosis patents application under Section 3(i) has come under judicial scanner multiple times. For instance, in the Chinese University of Hong Kong case, the Madras High Court questioned the refusal of a diagnostic patent based on in-vivo/invitro factor analysis. The Court junked the IPO Manual guidelines for limiting the allowability of the diagnostic to in vitro methods alone. The Court found that the self-imposed exception by IPO on the in vivo diagnostic process was not supported by the language of Section 3(i). Stepping aside the argument of exclusion under Section 3(i), the Court granted a patent for the invention “Fetal Genomic Analysis from a Maternal Biological Sample.” However, this grant did not deter IPO from refusing diagnostic-related patents.
Once again, the IPO refused the patent application filed by Natera Inc. for ‘Methods for Lung Cancer Detection’, stating that the subject matter as claimed was for the treatment/diagnosis of lung cancer and was not allowed under Section 3(i) of the Patents Act, 1970. Additionally, the Controller found that the newly added claims 5-8 were covered by Section 59 of the Patents Act, 1970, as the amendment sought was not by way of disclaimer, correction, or explanation. Natera filed an appeal before the Delhi High Court. In Natera Inc. and Anr vs The Assistant Controller of Patents and Designs, the Court appointed an Amicus Curiae to assist the Court in interpreting Section 3(i) of the Act, particularly the scope of exclusions from patentability under Section 3(i) in respect of diagnostic methods. The Delhi High Court, in its October 9, 2025, decision, affirmed the Controller’s order.
Case of the Appellant
The appellant, describing the invention, submitted that the first feature of the claimed invention was that the individual over whom the testing is done is someone who is already suspected of having ‘lung squamous cell carcinoma’, which is a ‘Non-Small Cell Lung Cancer’ (hereinafter “NSCLC”). It was also clear from the fact that within Claim 1 itself, the detection was of single ‘Single Nucleotide Variants’ which are associated only with this ‘lung squamous cell carcinoma’. The appellant argued that there was no diagnosis that took place in the subject test.
Accordingly, the appellant argued that the subject persons who already suffer from NSCLC were subjected to the detection according to the inventive method the claims propose to make, which relates to the nature and identification of the single nucleotide variant. The said identification using a bespoke Polymerase Chain Reaction (hereinafter “bespoke PCR”) was customised to suit only one person by generating specific primers. According to the appellant, the intention behind the subject test was to assess how many individuals who suffer from NSCLC had a particular variant. The results could be used both for the purposes of research and for checking the predisposition of a particular person.
The sensitivity of the test was to the extent that it could detect circulating DNA to the 0.01% variable. The method was also intended to check which mutations had the propensity to contact this particular form of cancer. Natera submitted that the applications could be several in respect of such methods; however, at least two clear applications were for research and for doing a predisposition test. The appellant cited the Madras High Court ruling in the Chinese University of Hong Kong and Anr. vs Assistant Controller of Patents & Designs, [2023 SCC OnLine Mad 6372] to argue that, as per the said judgment, the word ‘diagnostic’ was to be limited to diagnostic processes that disclose pathology for the treatment of human beings. Additionally, the appellant submitted that the fact that such individuals undergoing the subject test were already known to have this specific lung cancer itself shows that this was neither a diagnostic method nor was it being used for the purposes of any treatment.
Respondent’s Reply
The respondent maintained that the impugned order was well-reasoned, with clear elaboration of the refusal to grant a patent under Section 3(i). According to the respondent, the subject invention not only involved performing a multiplex PCR amplification reaction on nucleic acids isolated from a sample but also a determination step for the single-nucleotide variants present in lung squamous cell carcinoma. The respondent maintained that since the subject invention involved a diagnosis whereby the lung squamous cell carcinoma could be treated, the corresponding Claims 1 to 4 could not be permissible under Section 3(i) of the Act.
Opinion of the Amicus on Section 3(i)
The Court heard Mr. Adarsh Ramanujan, ld. Amicus Curiae, who was appointed in EMD Millipore vide order dated October 28, 2022, for the assistance of the Court in the interpretation of Section 3(i) of the Act, particularly the scope of exclusions from patentability under Section 3(i) of the Act in respect of diagnostic methods. The Amicus gave his opinion on what the scope of exclusions from patentability under Section 3(i) of the Act in respect of diagnostic methods is, and whether Natera’s invention was excluded from patentability under Section 3(i) of the Act. The Amicus also explained whether Claims 5 to 8 of the subject patent application would be impermissible in view of Section 59 of the Act.
Issue I: Scope of exclusions from patentability under Section 3(i) of the Act in respect of diagnostic methods
The Amicus pointed out that there was a drafting error in Section 3(i) of the Act, namely the non-inclusion of the words ‘methods for’ before the word ‘treatment’, suggesting that what is excluded from patentability is ‘diagnostic … treatment of human beings’. He referred to the judgment of the Madras High Court in the Chinese University of Hongkong, submitting that the requirement of practising on the human or animal body was no longer a requirement under Section 3(i) of the Act, and even tests made or conducted in the laboratories would fall within the scope of Section 3(i) of the Act. He submitted that the Act does not distinguish between in vitro and in vivo methods under Section 3(i). He relied on the decision of the Enlarged Board of Appeals of the EPO in Case Number G 0001/04, in which the term “diagnostic method” was interpreted to exclude method claims that cumulatively include several steps. He submitted that the said steps include:
- The examination phase involving the collection of data;
- The comparison of these data with standard values;
- The finding of any significant deviation, i.e., symptom, during the comparison, and
- The deductive medical/veterinary decision phase.
He argued that the steps dedicated solely to intermediate steps or screening methods that may have diagnostic relevance are not excluded. Therefore, a simple diagnostic method would not by itself be excluded from patenting, especially if it requires any follow-up with substantial steps to arrive at the treatment. According to him, it was only if the diagnostic process itself resulted in reaching a diagnosis for curative purposes without any further substantial activity that it would be excluded from patentability.
Issue II: Whether Natera’s invention is excluded from patentability under Section 3(i) of the Act?
For subject matter claimed by Natera, the only question while interpreting Section 3(i) of the Act, in the context of diagnosis and diagnostic process, was whether the literal language of the claim had to be seen or the intention had to be seen from the complete specification. The Amicus submitted that it was a question of claim construction as to whether, merely by the use of the process or methods applied for, a medical practitioner could treat human beings or animals. If the answer was yes, then it would be excluded. If the answer was no, it would not be excluded.
Court’s Analysis and Findings
Whether the subject patent is excluded from patentability under Section 3(i) of the Act? To answer this question, the Court examined the nature of the claimed process, its technical character, and the context of its application, and found that the purpose of the invention was to detect mutations associated with cancer using methods such as PCR. Such PCR methods are well known in the field of diagnosis. The summary set out various embodiments of the manner in which amplification methods, such as PCR, were used. The summary set out how sets of amplicons were generated using a multiplex amplification reaction on nucleic acids. The said nucleic acids were isolated from a blood sample from an individual suspected of having lung squamous cell carcinoma.
If the amplicons spanned even a single nucleotide variant known to be associated with lung cancer, then squamous cell carcinoma is diagnosed. Claim 2 states that the subject method would also identify/ diagnose the stage of lung squamous cell carcinoma as 1a, 1b, or 2a. It clearly showed that, at each stage, the test contemplated by the subject invention was either for detecting carcinoma or for supporting a lung cancer diagnosis. The description of the invention also showed that some embodiments were intended to support the diagnosis of squamous cell carcinoma or stage three carcinoma and to indicate the detection of other stages of carcinoma. The Court found the appellant’s submission that the subject invention did not detect disease to be completely meritless, as identification of the exact illness, problem, or cause would merely be one of the elements of diagnosis.
According to the Court, the term ‘diagnosis’ itself would mean the process of obtaining a result as to whether any particular medical condition exists or not, as well as the stage thereof, if any. The Court ruled that it could not be accepted that only methods that finally confirm the presence of a particular illness, disease, or medical condition constitute a diagnostic method. The Court gave interpretation of diagnostic methods as one where the result of performing a method would initially confirm the absence of a particular illness, disease, genetic defect, medical condition etc., or negation of the same in an individual, the said method would also fall within the scope of diagnosis under Section 3(i) irrespective of the said method being performed as an in vivo or invitro test.
The Court found reading of paragraphs 40, 41, 42, and 43 of the complete specification of the subject invention left no manner of doubt in the language which was used that upon conducting a test through an amplification method using bespoke PCR, the presence of cancerous cells was sought to be established/ identified. The Court observed that the subject invention was clearly hit by Section 3(i) of the Act, especially considering that the complete specification even confirmed that, in some embodiments, there was a definitive result being obtained as well. The Court also observed that it was conscious of the fact that insofar as cancer was concerned, the nature of the disease may require further test to be performed on the patient before the treatment begins, however, this by itself could not, in any manner, neutralise or dilute the purpose of the subject invention, i.e., that the process was meant to detect lung cancer. The Court noted that in view of the above discussion and the complete specification read with the final claims, it clearly showed that the subject patent was for a process for diagnosis and detection of lung cancer. The Court ruled that the statute, as it stands, therefore, would not permit the grant of a subject patent.
On Drafting of Claims
One cause of concern pointed out by the Court was that various claims which have been filed from time to time have tried to create a veil so that the claims can escape the objection of Section 3(i). However, as held in Novartis AG v. Union of India, (2013) 6 SCC 1, skilful drafting would not help in such cases.
On Patent Grants in Other Jurisdictions
On this argument, the Court quipped and ruled that the subject invention may have been patented in some foreign jurisdictions; however, the statutory prohibition in India being what it is, the mere grant in foreign jurisdictions would not lead to the grant of the patent in India.
On Inventive Step and Amendment of Claims Under Section 59
According to the Amicus, since dependent claims do not expand the scope of the original claim, they may be considered allowable. The Court noted that, insofar as the opinion of the Patent Office on inventive step or Section 59 of the Act was concerned, the same was not being gone into inasmuch as this Court was of the opinion that the subject patent was hit by Section 3(i) of the Act.
Court’s Decision
The Court rejected the contention of the appellant that there had to be an identification of the exact illness or its particular cause. It ruled that the subject invention fell within the scope of diagnosis under Section 3(i), irrespective of the said method being performed as an in vivo or in vitro test. In view of the above discussion, the appeal of the appellants against the refusal to grant the subject patent application failed and was liable to be dismissed.
Takeaways
The Delhi High Court clarified that even the manner in which the diagnosis was to be performed falls within the exclusion under Section 3(i), and that such diagnostic methods were not patentable. However, Section 3(i) exclusion would not extend to diagnostic tools, products, and devices and such inventions were considered patentable. The Court also clarified that Section 3(i) exclusions do not differentiate between in vitro and in vivo processes. Therefore, any manner of performing a diagnosis would not be patentable. The Court rejected the appellant’s argument that there had to be an identification of the exact illness for the application of Section 3(i) exclusions. The Court in Natera case gave interpretation of diagnostic methods as one where the result of performing a method would initially confirm the absence of a particular illness, disease, genetic defect, medical condition etc., or negation of the same in an individual, the said method would also fall within the scope of diagnosis under Section 3(i) irrespective of the said method being performed as an in vivo or invitro test. It meant that the subject application fell under Section 3(i), and the Court affirmed the rejection of the patent by the Controller.
Author: DPS Parmar
First Published by: Mondaq here