Summary
Indigenous Energy Storage Technologies Pvt. Ltd. ("IEST") holds Indian Patent No. 373806, covering a process for producing hard carbon from cattle manure for use in sodium-ion batteries and supercapacitors. Following a post-grant opposition, the Deputy Controller revoked the patent for lack of inventive step under Section 25(2)(e) and insufficient disclosure under Section 25(2)(g) of the Patents Act, 1970. The Delhi High Court found that the Controller had not followed the mandatory five-step test for evaluating inventive step established in F. Hoffmann-La Roche Ltd. v. Cipla Ltd., had applied hindsight reasoning, and had incorrectly recorded that IEST had been given an opportunity to furnish experimental data when the records showed otherwise. The court set aside the revocation order and remanded the matter for fresh consideration, with a direction to decide within four months. The ruling is a significant reminder that post-grant opposition adjudication must be structurally rigorous and procedural shortcuts in inventive step analysis will not survive appellate scrutiny.
Background
Indigenous Energy Storage Technologies Pvt. Ltd. (“IEST”) is an Indian company focused on transforming bio-waste, particularly cattle manure, into economically viable and environmentally sustainable battery components. Its Indian Patent No. 373806 (“IN’806”), titled Cattle Manure Derived Hard Carbon as Electrode Material for Sodium Ion Batteries and Super Capacitors, covers a multi-step process: drying the manure, grinding it, treating the ground material with hydrofluoric acid (HF) at a specified molar concentration and temperature, washing with de-ionised water, vacuum-drying, and finally calcinating at high temperatures under a controlled nitrogen or argon environment. The patent was filed on 4 November 2020, granted on 4 August 2021, and covers both the process and the resulting electrode material for sodium-ion batteries and supercapacitors.
A post-grant opposition was filed by Faradion Limited, a UK based company on 3 August 2021 under Sections 25(2)(b), (e) and (g) of the Patents Act, 1970, relying on three prior art references: D1 (WO 2020/208341, a PCT application on animal-derived hard carbon), D2 (Atkins’ Physical Chemistry, 8th edition, used for its water phase diagram), and D3 (US 2002/0192553, covering electrode formulations for sodium-ion batteries). The Deputy Controller of Patents (“the Controller”) rejected the novelty objection under Section 25(2)(b) but upheld both remaining grounds, revoking IN’806 on 18 October 2024. IEST appealed to the Delhi High Court under Section 117A of the Act.
Issues Before the Court
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- Whether the Controller’s revocation under Section 25(2)(e) for lack of inventive step was vitiated by failure to follow the five-step test mandated by F. Hoffmann-La Roche Ltd. & Anr. v. Cipla Ltd., 2015 SCC OnLine Del 13619
- Whether the Controller correctly applied the standard for Section 25(2)(g) for insufficient disclosure, or impermissibly conflated it with a requirement to produce comparative yield data
- Whether the Controller’s factual finding that IEST had been given and had failed to use an opportunity to furnish experimental data was borne out by the record
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IEST’s Arguments
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- The Controller did not identify the person skilled in the art (Step 1 of the F. Hoffmann test), did not identify the inventive concept embodied in IN’806 (Step 2), and did not assess whether the differences between the claimed invention and the prior art would have been obvious to a notional skilled person without hindsight (Step 5), rendering the revocation legally unsustainable.
- The claimed process differs fundamentally from D1: D1 mandatorily requires a charring/carbonisation step before acid treatment, uses HCl at elevated temperatures (80°C–120°C) rather than HF at 25°C–60°C, and subjects the starting material to sink-and-float pre-treatment steps entirely absent from IN’806. D1 therefore teaches away from the claimed invention.
- D2 (a water phase diagram from a chemistry textbook) is a non-analogous prior art with no connection to hard carbon synthesis; D3 relates to generic electrode formulations and does not disclose the specific HF-treated, non-charred hard carbon of IN’806. Mosaicking D1, D2, and D3 is impermissible because the post-grant opposer did not demonstrate why a skilled person would have been motivated to combine three documents from entirely different technical fields.
- The sufficiency ground under Section 25(2)(g) is met if at least one workable embodiment is fully disclosed. IEST’s specification provides multiple examples enabling a skilled person to practise the invention.
- The Controller’s repeated assertion that IEST was given and failed to use an opportunity to furnish experimental data was factually incorrect and contradicted by the record.
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Deputy Controller’s Arguments
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- The revocation order was a detailed, speaking order based on meticulous evaluation of the prior art; IN’806 neither represents technical advancement over existing knowledge nor carries economic significance.
- The drying step is implicit in D1, the HF concentration and mixing time ranges are mere numerical variations without demonstrated technical advantage, the drying parameters are derivable from D1 combined with D2, and the electrode composition in Claim 4 is rendered obvious by D1 read with D3.
- IEST failed to provide experimental yield data despite being asked to do so, making it impossible to assess industrial scalability or the superiority of the claimed process over D1.
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Court’s Analysis
The Five-Step Test Is Not Optional
The court’s primary and decisive finding concerned procedural method. The court noted that the five-step framework for assessing inventive step as articulated in F. Hoffmann-La Roche Ltd. v. Cipla Ltd. and affirmed by a subsequent Division Bench in Tapas Chatterjee v. Assistant Controller of Patents and Designs, 2025 SCC OnLine Del 6369 must be followed sequentially. Step 1, identifying the person skilled in the art, is not a formality: it anchors the entire obviousness inquiry, because the question is always what that person, equipped with common general knowledge at the priority date, would have found obvious. The Controller skipped this step entirely, and the court held that this omission alone vitiated the revocation order.
The fifth step, which was ruling out a hindsight approach, was also not followed. The court found that the Controller had, in effect, used IN’806 as a reverse roadmap, dissecting the claimed process into individual steps and then locating each step somewhere in the prior art, without asking whether a skilled person, reading the prior art without knowledge of the invention, would have had any reason to combine those elements in the way IN’806 does. The court cited Agriboard International LLC v. Deputy Controller of Patents and Designs, 2022 SCC OnLine Del 940 for the proposition that simply cataloguing elements of the prior art and concluding obviousness, without structured analysis, is contrary to Section 2(1)(ja) of the Patents Act.
Controller Failed to Engage with Substantive Differences
Beyond the structural failure, the court identified specific technical distinctions that the Controller had not properly considered. The absence of a charring step in IN’806 is not a trivial omission: D1 treats charring as essential to lock carbon into an insoluble matrix and improve purity. A skilled person reading D1 would have had no motivation to remove that step. The substitution of HF for HCl is also substantively significant as HF dissolves and removes SiO₂ and metallic impurities, a function HCl in D1 does not perform. These differences were raised in IEST’s reply to the opposition but were not genuinely engaged with in the revocation order.
Sufficiency Ground Misapplied
On Section 25(2)(g), the court found that the Controller had conflated sufficiency of disclosure with a requirement to demonstrate superior yield over prior art through comparative experimental data. The correct test is whether the specification enables a person of average skill in the relevant art to work the invention, not whether the patentee has proven quantitative superiority over every cited document. IEST’s specification included multiple worked examples sufficient to enable practice of the claimed process, and the opponent had conceded that the best mode had been disclosed.
Record did not support the Controller’s factual finding
The court called for the original records to verify the Controller’s repeated assertion that IEST had been given and had failed to use an opportunity to furnish experimental yield data. The records did not substantiate that assertion. Given this finding, the court allowed IEST’s application to place additional experimental evidence on record, relying on Union of India v. Ibrahim Uddin and Another, (2012) 8 SCC 148, which permits additional evidence where it is crucial for just adjudication.
Findings
In view of the observations and the arguments presented by both the parties, the Delhi High Court held that:
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- The Controller’s revocation of IN’806 under Section 25(2)(e) was vitiated because the mandatory five-step inventive step test from F. Hoffmann-La Roche v. Cipla was not followed, in particular, the person skilled in the art was not identified and a hindsight approach was applied.
- The Controller failed to engage substantively with the differences identified by IEST between the claimed process and D1, including the absence of a charring step and the use of HF rather than HCl.
- The revocation under Section 25(2)(g) was unsustainable because the Controller misapplied the sufficiency standard and the factual finding that IEST had failed to provide experimental data despite opportunity was not borne out by the record.
- The additional evidence filed by IEST before the High Court, including expert opinion and yield data, was admitted in the interest of just adjudication.
- The revocation order was set aside and the matter remanded to the Controller for fresh consideration of the post-grant opposition, taking into account all additional documents, IEST’s reply submissions, and all issues raised in the appeal.
- The Controller was directed to decide afresh after hearing both parties within four months; the High Court expressly declined to express any opinion on the merits.
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Case Citation: Indigenous Energy Storage Technologies Pvt. Ltd. v. Deputy Controller of Patent and Designs & Anr., C.A.(COMM.IPD-PAT) 3/2025, Delhi High Court, decided on 12 March 2026. Available at https://indiankanoon.org/doc/168733956/
Authored by Gaurav Mishra, Patent Attorney, BananaIP Counsels