Summary
The Delhi High Court upheld the rejection of a patent application for a process claiming zero liquid discharge from distillery waste. The court ruled it lacked inventive step and was merely a combination of known techniques, thus falling under Section 3(d) of the Patents Act.
In the present case, the Delhi High Court upheld the rejection of a patent application for a process to recover potassium sulphate and other products from distillery waste. The court found that the claimed invention was a mere combination of known processes, lacking inventive step under Section 2(1)(ja) and falling within the exclusion under Section 3(d) of the Patents Act, 1970.
Background:
Tapas Chatterjee filed a patent application (No. 201911036748) for a process titled “Recovery of Potassium Sulphate and other valuable products from Spent Wash leading to ZLD (Zero Liquid Discharge) System”. The invention disclosed a process to recover multiple useful substances, such as potassium sulphate, magnesium sulphate, activated carbon, and reusable water, from distillery spent wash, a high-pollution effluent generated during alcohol production.
The Council of Scientific and Industrial Research (CSIR) filed a pre-grant opposition under Section 25(1)(b), (e), (f), and (g) of the Patents Act, 1970. Among other grounds, CSIR contended that the claimed invention was not novel, was obvious in light of existing prior art, lacked inventive step, and fell within the exclusions under Section 3(d) of the Act as a mere use of known processes. The opposition was primarily based on disclosures in two prior art documents.
The Assistant Controller of Patents examined the opposition and upheld the objections under Section 25(1)(e) (lack of inventive step) and Section 25(1)(f) read with Section 3(d). Consequently, the application was rejected.
Aggrieved by this decision, the appellant challenged the rejection before a Single Judge of the Delhi High Court, who dismissed the appeal on March 10, 2023. The Appellant then filed a Letters Patent Appeal (LPA) against the Single Judge’s judgment.
Issues:
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- Whether the claimed invention lacked inventive step under Section 2(1)(ja), attracting rejection under Section 25(1)(e).
- Whether the invention was excluded from patentability under Section 3(d) as a mere use of a known process.
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Appellant’s Arguments:
Tapas Chatterjee, the Appellant, argued that:
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- The invention was novel and inventive, addressing shortcomings in prior art for recovering potash-based fertilizers from spent wash.
- The process involved unique steps such as removing high molecular weight organic compounds from spent wash to obtain a first liquid fraction, concentrating it to a first solid fraction, thermal decomposition to a second solid fraction, dissolving it in a solvent for a second liquid fraction, and recovering potassium sulphate.
- Prior arts D1 (US Patent) and D2 (BIS Guide) cited by the Opponent did not disclose the complete sequence or achieve ZLD/ Zero Liquid Discharge, nor did they recover multiple value-added products economically.
- The invention overcame limitations in existing patents providing a simple, economical method.
- The Assistant Controller’s findings were laconic and failed to substantiate obviousness from the perspective of a “person skilled in the art” (PSITA).
- On Section 3(d), the Appellant argued that the invention was not a mere discovery but a new process resulting in enhanced efficacy, including ZLD and recovery of by-products like activated carbon and magnesium sulphate.
- The Single Judge erroneously applied the Hoffmann-La Roche test for obviousness, ignoring differences in the inventive steps.
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Arguments of the Respondents:
The Assistant Controller (Respondent No. 1) and CSIR (Respondent No. 2) argued that:
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- The invention lacked inventive step under Section 25(1)(e), as it was obvious to a PSITA based on D1 (which disclosed recovery of potassium salts from distillery waste) and D2 (which outlined treatment methods for distillery effluents, including incineration and potash recovery).
- Combining D1 and D2 would lead a skilled person to the subject process without inventive ingenuity, as both addressed similar effluent treatment challenges.
- Under Section 3(d), the process was merely a new use of known substances/processes (e.g., concentration, thermal decomposition) without demonstrating enhanced efficacy or a new product.
- The Assistant Controller’s order was reasoned, rejecting novelty but upholding obviousness, and the Single Judge correctly upheld this by applying established precedents on mosaicing prior art.
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Court’s Analysis:
The Division Bench critically examined the patent regime’s challenges, noting that the absence of guidelines for assessing “obviousness” often lead to subjective decisions by examiners. While analyzing the issue relating to Section 3(d), the court held that under Section 3(d), for a process to be patentable, it must result in a new product or use at least one new reactant. According to the court, all individual steps of the claimed process were disclosed in prior art (D1 and D2). The court said the process merely combined known steps and resulted in a known product – potassium sulphate. The claimed zero liquid discharge aspect did not transform the end product or demonstrate a new reactant.
The Court noted that the term “known process” in Section 3(d) includes combinations of known processes. The court observed that there was no enhancement in efficacy or novelty in the end product.
While analyzing the Inventive Step under Section 2(1)(ja), the court applied the five-step test from F. Hoffmann-La Roche Ltd. v. Cipla Ltd. The court said the processes described in D1 and D2 were substantially similar to the claimed invention. The steps of evaporation, thermal decomposition, and crystallisation were standard chemical operations. Therefore, the court found that the claimed process did not involve any inventive step.
The court further held that even if the combination of steps was novel, it was obvious and did not involve any technical advance or economic significance. Thus, the claim failed under Section 25(1)(e).
The Court criticized the Assistant Controller’s brief findings but upheld them, finding no error in the Single Judge’s application of law. It highlighted systemic issues in patent examination, calling for more objective standards.
Conclusion:
The Delhi High Court, while affirming the rejection of the application, clarified important principles governing the patentability of process inventions under Indian patent law. The court held that a process composed entirely of known steps, producing a known product without any new reactant or demonstrable technical advancement, does not qualify as an invention under Section 3(d) of the Patents Act. Further, the court reiterated that inventive step must be assessed from the perspective of a person skilled in the art, and that the claimed process in this case was obvious in light of the cited prior art. By applying the established test for obviousness and distinguishing between inventive and non-inventive combinations of known techniques, the court reinforced the statutory standards for patent grant. The claimed zero liquid discharge benefit, in the absence of a novel product or new technical contribution, was therefore held to be insufficient to overcome these requirements.
Citation: Tapas Chatterjee v. Assistant Controller of Patents and Designs & Anr., LPA 836/2023, decided on 6 October 2025, Delhi High Court. Available at: https://indiankanoon.org/doc/31719152/
