Decoding Diagnostic Method Patents: The MHC:4617 Case and India’s Patent Eligibility Conundrum


In the ever-evolving landscape of patent law in India, a recent judgment by the Madras High Court has stirred significant interest and debate. The case, The Chinese University of Hong Kong v. The Assistant Controller of Patents & Designs (MHC:4617)[1], centers on the interpretation and application of Section 3(i) of the Patents Act, 1970, specifically in the context of a diagnostic method for fetal genomic analysis. This article delves into the intricacies of this landmark case, examining the arguments put forth by both the appellants and the respondents, along with the perspective of an amicus curiae. At its core, this case raises thought-provoking questions about the patent eligibility of diagnostic methods, particularly in the realm of medical diagnostics, within the Indian legal framework.


The appellants, the Chinese University of Hong Kong Knowledge Transfer Office, and SEQUENOM, INC., filed a patent application (IN 4812) for a non-invasive prenatal screening test (NIPT) to determine fetal genomic information from a maternal biological sample. The dispute arose when the Assistant Controller of Patents rejected the patent application under Section 3(i) of the Patents Act, 1970, deeming it a diagnostic method, a non-patentable subject matter under S. 3 of the Patents Act.

Arguments and Contention:

Appellants’ Position:

The appellants argued that their NIPT method is not a diagnostic method as it does not diagnose any disease in a patient. They contended that Section 3(i) should be interpreted in a way that confines the term “diagnostic” to in vivo diagnosis and does not encompass in vitro diagnosis methods. The appellants referred to the Manual of Patent Office Practice and Procedure, 2010, which distinguishes between in vivo and in vitro diagnosis. They also pointed out that the European Patent Convention excludes only in vivo diagnostic methods.

Amicus Curiae’s Argument:

The amicus curiae, Mr. Adarsh Ramanujan, argued that a drafting error exists in Section 3(i), suggesting it should be read as “any process for the medicinal, surgical, curative, prophylactic diagnostic, therapeutic, or other methods for treatment of human beings.” He traced the history of exclusions from patent eligibility in Indian patent law. He argued that the exclusion of methods of treatment of human beings is based on non-patentability rather than public policy.

Respondent’s Position:

The Assistant Controller of Patents, supported by the learned SPC, contended that the complete specification claimed the method’s diagnostic nature which is prime facie non-patentable under the Patents Act. They argued that Section 3(i) does not limit the term “diagnostic” to in vivo diagnosis and that the presence of the word “process” implies that all method steps involved in a diagnosis qualify as diagnostic methods.

Let’s dissect this case to draw an analysis of the findings at the end.

Construction of Section 3(i)

The construction of Section 3(i) of the Patents Act is central to this case. Section 3(i) of the Patents Act, 1970 reads as follows:

> “3. What are not inventions – The following are not inventions within the meaning of this Act,-

(i) any process for the medicinal, surgical, curative, prophylactic diagnostic, therapeutic, or other treatment of human beings or any process for a similar treatment of animals to render them free of disease or to increase their economic value or that of their products.”

This section comprises two distinct limbs:

(a) any process for the medicinal, surgical, curative, prophylactic diagnostic, therapeutic, or other treatment of human beings; and

(b) any process for a similar treatment of animals to render them free of disease or to increase their economic value or that of their products.

The two limbs are separated by the disjunctive ‘or,’ and the second limb specifically addresses animal treatment, setting out three purposes of such treatment.

Distinct and Self-Contained Limbs:

In the interpretation of Section 3(i), it becomes evident that each limb is distinct and self-contained, dealing with different subjects. The first limb pertains to human beings, while the second pertains to animals. The use of the disjunctive “or” further separates these two limbs. The second limb explicitly addresses the treatment of animals for specific purposes and does not apply to human beings, particularly because human treatment is not intended to increase economic value.

This separation reinforces the idea that the second limb only pertains to the treatment of animals, and the pronoun “them” in the second limb is meant to reference only animals and not human beings. Additionally, treatment is provided to humans for various purposes, including curing diseases, preventing diseases, and managing conditions, indicating that the word “treatment” should be construed broadly in the context of the first limb.

Diagnostic – An Oddity in Section 3(i):

An interesting aspect of Section 3(i) is the inclusion of the term ‘diagnostic.’ In medical science, diagnosis is the process of identifying diseases, disorders, or conditions. This identification, per se, cannot be considered a form of treatment. As a result, the expression “any process for the diagnostic treatment of human beings” does not make complete sense, unlike the other forms of treatment listed in the section.

The term ‘diagnostic’ stands out because it does not describe a form of treatment like the other expressions in the section (medicinal, surgical, curative, prophylactic, therapeutic). While each of these terms describes a method of treatment, ‘diagnostic’ is distinct because it involves identifying the presence or absence of a disease, disorder, or condition, rather than treating it.

Interpreting ‘Diagnostic’:

The word ‘diagnostic’ in Section 3(i) should be considered in association with the other words in the section and read in the context of its meaning. Diagnosis is an essential prerequisite for rational treatment. Sometimes the link between diagnosis and treatment is close, while at other times, there can be a considerable time gap between diagnosis and treatment. Regardless, diagnosis and treatment are considered distinct processes.

The juxtaposition of the word ‘diagnostic’ with terms like ‘medicinal’ and ‘surgical,’ which undoubtedly describe forms of treatment, suggests that ‘diagnostic’ should be interpreted in the context of identifying pathology for the treatment of human beings.

In Vivo vs. In Vitro Diagnosis:

The text of Section 3(i) was amended in 2002 to include ‘diagnostic’ and ‘therapeutic.’ The language of Section 3(i) does not indicate that ‘diagnostic’ should be limited to in vivo diagnosis. No evidence in the text or statutory context supports this interpretation.

TRIPS Agreement and International Context:

Article 27 of the TRIPS Agreement, which deals with patentable subject matter, addresses patent eligibility. Article 27(3)(a) permits members to exclude from patentability “diagnostic, therapeutic, and surgical methods for the treatment of humans or animals.” It is clear from this provision that diagnostic methods should be for the treatment of humans or animals, but no further limitations are evident.

While the communication from the Permanent Mission of India contained a proposal to limit patent ineligibility to diagnostic methods practiced on the human or animal body, this proposal did not find expression in the final draft of the TRIPS Agreement.

Patent Office Manuals:

In the context of Patent Office Manuals, it is found that Section 3(i) was narrowly interpreted, particularly in the 2005 Draft and Final Manual, excluding patent eligibility solely for in vivo diagnostic methods. The 2008 and 2010 Manuals contained similar language. However, the 2019 Manual offered a different definition of diagnostic methods. It defined diagnostic methods as the identification of medical illnesses by investigating their history, and symptoms, and applying tests, not limiting it to in vivo diagnosis.

The 2019 Manual also provided examples of subject matter excluded under Section 3(i), such as diagnosis on the human or animal body. This approach was consistent with the 2013 Guidelines. The judgment emphasizes that current patent manuals and guidelines do not limit patent ineligibility to in vivo diagnostic methods. It also underscores that these manuals are not determinative of Section 3(i) scope but offer insights into how the Patent Office interpreted the provision.

EBoa Opinion:

Regarding the EBoA (Enlarged Board of Appeal) opinion, it considered Article 52(4) of the European Patents Convention (EPC), which excludes methods for treatment and diagnostic methods on the human or animal body from patentability. The EBoA opinion concluded that the text of Article 52(4) suggests a narrow interpretation, as it includes the phrase “diagnostic methods practiced on the human or animal body.” Unlike Article 52(4) of the EPC, Section 3(i) does not contain this phrase, further supporting the conclusion that “diagnostic” in Section 3(i) extends to both in vitro and in vivo diagnosis.

The EBoA also discussed the four method steps involved in diagnosis: (1) collecting data, (2) comparing data with standard values, (3) finding deviations, and (4) attributing deviations to a clinical picture. It considered two interpretations: a narrow one, requiring all four steps, and a broad one, excluding all steps related to diagnosis or useful for diagnosis. The EBoA adopted the narrow interpretation to exclude methods with all four steps from patent protection.

The judgment highlights that in the case of in vivo diagnosis, various medical professionals usually perform these methods, involving all four steps. However, in in vitro diagnosis, non-medical professionals can perform the first three steps, while the clinical diagnosis is made by a medical doctor. Therefore, the judgment suggests that the EBoA’s narrow interpretation could be circumvented more easily in the context of in vitro diagnosis.

Other Observations:

The judgment also mentions that the European Patent Office (EPO) formulated principles and measures to prevent clever patent claims drafting and circumvention of patent ineligibility, as well as the “inevitable results of the test” as a filter to weed out patent-ineligible claims camouflaged by clever claims drafting.

Furthermore, the judgment discusses the language of Section 3(i), particularly the use of “diagnostic” in conjunction with treatment forms and “other treatment of human beings.” It emphasizes the need for the construction of a “diagnostic” that aligns with the text and context, neither unduly curtailing nor expanding it. The proposed standard is to examine claims in the context of the complete specification to determine if they specify a process for making a diagnosis for treatment, with the assumption that a skilled person, including a medical doctor, examines the claims and complete specification.

The judgment addresses the question of whether certain tests should be excluded from the definition of “diagnostic” in Section 3(i). It suggests that the embodiments of a claimed invention are relevant only for ascertaining whether the claimed invention inherently points to a diagnosis for treatment. It also distinguishes between screening and diagnosis, stating that a test qualifies as diagnostic if it can identify a disease, disorder, or condition for treatment, regardless of whether the person tested is symptomatic or asymptomatic.

The judgment provides a thorough analysis of the patent application and concludes that the claimed invention is not “diagnostic” under Section 3(i) since it does not diagnose a medical condition but rather identifies the foetal fraction. It highlights that further testing is needed to diagnose a condition, and the claimed invention merely provides an indicator for such testing. Consequently, the judgment suggests that the application should proceed to grant based on the amended claims.

Finally, the judgment calls for a reconsideration of the scope of “diagnostic” in Section 3(i) to incentivize inventors in cutting-edge diagnostic areas without compromising public policy exclusions. It suggests the possibility of restricting the scope to in vivo processes while providing for compulsory licensing to achieve a balance.


The judgment in the case of MHC:4617 raises pertinent questions about the interpretation of Section 3(i) of the Patents Act, 1970 in the context of diagnostic methods for fetal genomic analysis, but there are notable shortcomings and areas where the court’s handling of the matter could have been improved. First, the court’s interpretation of “diagnostic” as being contextually aligned to identify diseases or conditions for the treatment of human beings is indeed reasonable, but it falls short in providing a comprehensive historical analysis of this provision and its legislative intent, which would have added depth to the judgment.

Second, while the court acknowledges the TRIPS Agreement, it could have delved deeper into the international context, explicitly examining how other jurisdictions interpret and apply similar provisions. This would have provided a broader comparative perspective and enriched the analysis.

Third, the distinction between in vivo and in vitro diagnosis is a crucial aspect of patent eligibility, and the court, while touching on it, could have offered a more extensive exploration of how these distinctions impact the patenting of diagnostic methods. Additionally, the court briefly mentions the influence of Patent Office Manuals, but it could have provided a more robust assessment of their role in shaping patent eligibility criteria.

Fourth, the judgment references the European Patent Office’s Enlarged Board of Appeal (EBoA) opinion but does not thoroughly explore the differences between the European approach (which adopts a narrow interpretation of diagnostic methods) and the Indian stance. A more comprehensive comparison of these two perspectives could have been insightful.

Fifth, the court’s call for a reconsideration of the scope of “diagnostic” in Section 3(i) and the suggestion of compulsory licensing as a means to balance innovation and public policy are intriguing but lack a detailed discussion of the potential challenges and consequences of such policy changes.

Finally, the judgment, while generally well-reasoned, could benefit from added clarity and precision, particularly in explaining the specific grounds on which it concludes that the patent application should proceed to be granted. A more explicit elucidation of this aspect would enhance the judgment’s overall quality.

While the court’s judgment offers a comprehensive analysis of the patent eligibility of diagnostic methods, there are several notable shortcomings, such as the lack of a thorough historical analysis, a deeper exploration of international influences, and a more extensive comparison of the Indian and European perspectives. Moreover, the judgment could be more specific and explicit in certain areas. Addressing these limitations would lead to a more thorough and robust assessment of this pivotal case in Indian patent law and would serve as a precedent for years to come.

[1] The Chinese University of Hong Kong v. The Assistant Controller of Patents & Designs, The Patent Office. 2023:MHC:4617

About Amisha Mittal 12 Articles
Amisha Mittal is a final-year law student pursuing a BA. LLB. (Hons) at Jindal Global Law School, Haryana. Her interest areas align with Intellectual Property Law, Competition law and other technology related laws. She shares a passion for research and writing and with a strong interest in academia, she aspires to contribute to the legal scholarship in these areas.

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