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Navigating Patent Eligibility in Prenatal Testing: Unpacking the Legal Intricacies

By - King Stubb & Kasiva on November 28, 2023


In a ground-breaking decision of the case The Chinese University of Hong Kong and Sequenom, Inc. v. The Assistant Controller of Patents and Designs, CMA (PT) No.14 of 2023 & CMP No.16669 of 2023 on October 12, 2023, the Madras High Court addressed the complex issue of patent eligibility in prenatal testing. The case, CMA (PT) No.14 of 2023, centers around the interpretation of Section 3(i) of the Indian Patents Act, 1970 which excludes certain processes, especially those linked to the diagnostic treatment of human beings, from patent eligibility. This judgment is pivotal in shaping the legal landscape concerning emerging technologies in medical diagnostics.

Case Timeline:

  • Origins of the Case: The case originated from a patent application, IN 4812, which detailed methods for determining the fractional concentration of fetal DNA in prenatal testing.
  • Objections and Amendments: Following objections, the original claims 1-33 were deleted, leaving only amended claims 1-12 for consideration.
  • October 12, 2023: The Madras High Court rendered its verdict on CMA (PT) No.14 of 2023.

Issue Raised: The primary contention revolves around the interpretation of Section 3(i) of the Indian Patents Act, 1970. The core question is whether the patented method, despite not offering a definitive medical diagnosis, qualifies as a diagnostic process, thereby falling within the excluded category.

In-Depth Analysis:

Appellant’s Nuanced Argument:

The Appellants presented a nuanced argument, urging the court to evaluate the patent eligibility based on the amended claims. Their central assertion is that the invention, involving the analysis of nucleic acid molecules to identify the foetal fraction, serves as an indicator necessitating further testing but does not provide a conclusive diagnosis of a medical condition. They emphasized that the method does not diagnose a medical condition; rather, it merely identifies the foetal fraction. According to the Appellants, this places their invention outside the purview of Section 3(i). Furthermore, they contested the idea of evaluating patent eligibility by examining one specific use case or embodiment of the invention, advocating for an assessment based on the amended claims.

Respondent’s Broad Interpretation:

In contrast, the Assistant Controller relied on paragraph [0007] of the complete specification to argue that the claimed method is diagnostic. The Respondent contends that even though the invention may necessitate further testing, it falls under the category of diagnostic processes as outlined in Section 3(i). The emphasis is placed on the broader language used in the specification, indicating that the method can determine the risk of genetic diseases, predispositions, or traits, thereby justifying its classification as diagnostic.

Crucial Judgment Criteria:

The judgment, rendered on October 12, 2023, delved into the heart of the matter, providing a meticulous analysis of the arguments presented. The judge considered the language used in the amended claims, pointing out that the biological sample is drawn from the pregnant female subject, and the nucleic acid molecules are tested with the aim of identifying the foetal fraction. The judge acknowledged the significance of the foetal fraction as an indicator for further testing but pointed out that until the stage of identifying chromosomal aberrations (typically requiring not less than 4% foetal DNA), pathology remains undisclosed, rendering treatment impractical. The judge concluded that the invention provides an indicator relevant for further testing and does not qualify as a diagnostic process as contemplated by Section 3(i).

Setting a Precedent:

The analysis of this case sets a precedent for future cases involving patent eligibility in the realm of medical diagnostics. It establishes a nuanced understanding of the term ‘diagnostic’ in Section 3(i) and emphasizes that the scope should not be unduly curtailed by limiting it to in vivo or definitive diagnosis. The Court recognizes the evolving landscape of medical diagnostics, urging a reconsideration of the term ‘diagnostic’ to accommodate emerging technologies.

Call for Legislative Reconsideration:

The judge, in a notable observation, recognized the inconsistency in the Patent Office granting patents to in vitro processes and suggested that there is a case for legislative reconsideration. The judge highlighted the need to incentivize inventors in these cutting-edge areas without compromising on the public policy exclusion from patent eligibility of methods of diagnosis and treatment adopted by medical doctors. This observation opens the door for potential legislative amendments to accommodate advancements in diagnostic technologies while maintaining the necessary safeguards.


In summary, the Madras High Court’s ruling in the present case offers an in-depth analysis of the eligibility criteria for patents in prenatal testing. Originating from a patent application, the case delves into the intricacies of Section 3(i) of the Indian Patents Act,1970 establishing a precedent for future legal proceedings. The thorough examination of the revised claims, arguments from both sides, and the judge’s interpretation collectively contribute to a nuanced comprehension of the changing landscape of patenting medical diagnostics in India. While specific to this case, the judgment carries broader implications for patent eligibility, especially in emerging technologies. It underscores the importance of striking a balance that encourages innovation while respecting the public policy considerations within the legal framework. As India advances in medical diagnostics, this ruling serves as a guiding principle, addressing the complexities of patent eligibility.

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