Safiya Malik

The High Court of Delhi, Division Bench of Justice C. Hari Shankar and Justice Ajay Digpaul set aside the orders of the Assistant Controller of Patents and Designs and a Single Judge that had refused patent protection to inventor Tapas Chatterjee’s process for recovering potassium sulphate and other by-products from distillery spent wash. The Court held that the earlier authorities had not given adequate and reasoned consideration to whether the claimed process involved an inventive step or was barred as a mere use of known processes under Section 3(d) of the Patents Act, and directed the Controller General of Patents to reconsider the application afresh. The dispute centered on whether Chatterjee’s zero-liquid-discharge recovery process constituted a patentable technical advance or was obvious in light of prior art cited by the Council of Scientific and Industrial Research (CSIR), which had opposed the application.

The appellant, Tapas Chatterjee, filed on 12 September 2019 a process patent titled “Recovery of Potassium Sulphate and other valuable products from Spent Wash leading to ZLD System.” The specification sets out sequential steps: removing high molecular weight organics from spent wash to obtain a first liquid fraction; concentrating to obtain a first solid fraction; thermally decomposing that solid to obtain a second solid fraction; dissolving to form a second liquid fraction; and recovering potassium sulphate. It further describes recovery of reusable water, magnesium sulphate and activated carbon as value-added products, presenting the overall process as zero liquid discharge. Figures and a detailed description explain the flow of operations and the alternative routes for by-products.

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A First Examination Report issued on 25 February 2020, and a reply was submitted on 27 March 2020; the Assistant Controller’s order later adjudicated only the subsequent pre-grant opposition. The Council of Scientific and Industrial Research (CSIR) opposed the application under Section 25(1)(b), (e), (f) and (g), relying principally on prior art D1 (US 2018/0257945) and D2 (BIS Guide IS:8032-1976), with D3 and D4 cited for contextual details.

On 28 December 2021, the Assistant Controller rejected the opposition under Section 25(1)(b), Section 25(1)(f) insofar as it invoked Section 3(a), and Section 25(1)(g), but upheld the objections under Section 25(1)(f) read with Section 3(d) and under Section 25(1)(e). The order reasoned that several claim steps were standard operations and that, in view of D1/D2 (alone or in combination with D3/D4), the claims lacked inventive merit; the application was refused.

The appeal before the Intellectual Property Division was dismissed on 10 March 2023. The Single Judge held that the process combined known steps, used no new reactant, yielded no new product, and therefore fell within Section 3(d) and lacked inventive step under Section 2(1)(ja). A comparative analysis with D1 and D2 was presented in that judgment.

In the present Letters Patent Appeal, reserved on 3 April 2025 and pronounced on 6 October 2025, the Division Bench of Justice C. Hari Shankar and Justice Ajay Digpaul considered the record, including the specification, prior art comparisons, the Assistant Controller’s order, and the Single Judge’s judgment. The Bench examined whether the findings on Section 3(d) and on inventive step under Section 25(1)(e) read with Section 2(1)(ja) were supported by adequate reasons and by a proper application of the settled method for assessing obviousness.

The Court recorded, “neither the order of the AC, nor the impugned judgement, contain sufficient reasons to make out a case for rejecting the subject application either under Section 3(d) or under Section 25(1)(e) read with Section 2(1)(ja) of the Patents Act.” It stated, “we are of the opinion, therefore, that the entire issue would have to be re-examined by the office of the CGPDTM, and a proper and reasoned order passed.”

Addressing the test in F. Hoffmann-La Roche, the Bench recorded the five steps and observed that the Single Judge’s approach departed from the proper sequence. It stated, “The learned Single Judge could not have commenced applying the principles in Hoffmann from Step 4… Identification of the person skilled in the art is, therefore, the fundamental first step while examining a plea of obviousness and lack of inventive step.” It added, “Steps 2 and 3 are no less significant… it would be possible to gauge the distance that would be required to be scaled, to leap from one to the other.”

On inventive step, the Court stated, “The finding, of the learned Single Judge, as also of the AC, that the process that the appellant desires to patent is obvious from the prior art documents D1 and D2 is not, therefore, in our view, supported by sufficient material to sustain it. It has, therefore, to be set aside.”

On Section 3(d), the Court recorded, “In order for a later process to be rejected as non-patentable on the ground of Section 3(d), it must be shown, positively, that the later process is a mere use of the earlier process.” It stated, “Even then, Section 3(d) would not apply if the later process results in a new product or employs at least one new reactant.” It further observed, “there is no material on the basis of which it could be said that the process forming subject matter of the Claims in the subject application are ‘known’, or a ‘mere use’ of the processes envisaged in D1 or D2… at the very least, magnesium sulphate and activated carbon are among the products… which find no mention in D1 or D2.”

The Bench also noted the Assistant Controller’s rejection of novelty objections alongside a finding of obviousness, and recorded the need for a reasoned reconciliation when novelty is upheld but inventive step is denied.

The Court held, “The impugned judgment dated 10 March 2023, passed by the learned Single Judge, as well as the order dated 28 December 2021, passed by the AC, are quashed and set aside.” It directed, “Application No. 201911036748, submitted by the appellant, as well as the pre-grant opposition filed by CSIR, are remanded to the CGPDTM for consideration and determination afresh.”

“The consideration shall, however, be restricted to the objection of CSIR predicated on Section 25(1)(e) read with Section 2(1)(ja) of the Patents Act, based on the prior art documents cited by CSIR. No new material would be permitted to be placed on record.” It further held, “We reject the objection of CSIR that the subject process is not patentable because of Section 3(d) of the Patents Act.”

“The de novo consideration would be carried out strictly in terms of the principles enunciated in Hoffmann as well as in the present judgment.” It recorded, “The appellant, as well as CSIR, would be at liberty to place, on record before the CGPDTM, notes of the submissions…” and “The adjudicating authority… would afford, to both sides, an opportunity of hearing… Neither side would be permitted to seek an adjournment.”

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“The designated adjudicating authority would pass a reasoned and speaking order…” and recorded, “The de novo proceedings would be on the basis of the material already on record… however… the adjudicating authority may, at his discretion, permit such reliance [on authoritative material].”

The Court fixed a timeline and reserved rights, stating, “We direct the adjudicating authority to pass a fresh order… within a period of 6 months from the date of hearing.” and, “Should either side remain aggrieved… all legal rights and remedies… would remain reserved.” It clarified, “we have not expressed any binding opinion or view on… inventiveness or obviousness… No observation… is to be understood as… binding the adjudicating authority.”

Advocates Representing the Parties
For the Petitioners: Mr. Pravin Anand, Ms. Prachi Agarwal, Ms. Arpita Kulshrestha, Ms. Elisha Sinha, Advocates.
For the Respondents: Mr. Vijay Joshi, Mr. Kuldeep Singh, Mr. Shubham Chaturvedi, Advocates; Ms. Vindhya S. Mani, Mr. Ritvik Sharma, Ms. Naina Gupta, Mr. Bhuavan Malhotra, Ms. Surbhi Nautiyal, Ms. Harshita Agarwal, Mr. Devesh Aswal, Ms. Vedika Singhvi, Advocates

 
Case Title: Tapas Chatterjee v. Assistant Controller of Patents and Designs & Anr.
Neutral Citation: 2025: DHC: 8824 - DB
Case Number: LPA 836/2023, CM APPL. 66718/2023, CM APPL. 66719/2023, CM APPL. 66720/2023, CM APPL. 66721/2023 & CM APPL. 66722/2023
Bench: Justice C. Hari Shankar; Justice Ajay Digpaul