Summary: The judgment provides the standard of scrutiny applicable to patent applications and pre-grant opposition proceedings under Section 25(1) of the Patents Act 1970.
On October 6, 2025, in a Patent Appeal, the Division Bench (“DB”) of the Delhi High Court in Tapas Chatterjee v. Assistant Controller of Patents and Designs & Anr.[1] decided on the sustainability of an order the Assistant Controller of Patents and Designs (“AC”) had passed in a pre-grant opposition proceeding under Section 25(1) of the Patents Act 1970 (“Act”). Quashing the impugned order and judgment of the Single Judge that decided the appeal under Section 117A of the Act, the Bench remanded the matter to the Patent Office for a limited reconsideration of the patent application.
Background
The matter concerned a process patent titled “Recovery of Potassium Sulphate and other valuable products from Spent Wash leading to ZLD System”, where the process was presented as an environmentally sustainable, economical, and simpler way of “recovering potassium sulphate, magnesium sulphate, activated carbon and additional value-added products” from ‘spent wash’ that could achieve “zero liquid discharge.”[2] The Council of Scientific and Industrial Research (“CSIR”) then filed a pre-grant opposition on the grounds of absence of novelty and inventive step that impaired patentability under Clauses (b), (e), (f), (g) of Section 25(1) of the Act, arguing that the invention did not reveal technical advance or economic significance. Besides, it merely used a known process, neither generating a new product nor using at least one new reactant. The Applicant contended that the teachings in the prior arts D1[3] and D2[4] were distinct and could not be combined as submitted by CSIR. In its order dated March 10, 2023, the AC found merit in the objections under Sections 25(1)(e) and (f) read in conjunction with Section 3(d) of the Act. While the AC observed that the proposed invention was novel, as prior arts D1 and D2 did not disclose the same features, it was obvious and lacked inventive step. The AC also held that the claimed process did not delineate any new reactant or yield a new product. Consequently, it was not patentable per Sections 25(1)(e) and (f) read with Section 3(d). Aggrieved by this order, the Appellant filed an appeal under Section 117A to the Intellectual Property Division of the court.
The Single judge upheld the order of the AC. At the outset, the single judge held that the Applicant had been unable to show that the claimed process uses a new reactant or produces a new product, and the test of patentability under Section 3(d) was therefore not satisfied. The Court also conducted a comparative exercise for investigating the presence of inventive step and concluded that the invention utilised processes mentioned/disclosed in the cited prior art with differences only in terminology or addition of steps which are already well known. Therefore, the invention lacked inventive step under Section 2(1)(ja) of the Act.
Order of the Division Bench (DB)
The Court held that the impugned order passed by the AC reflected a mechanical application of statutory provisions without evaluating their applicability to the peculiar facts of this matter. The DB noted that despite a positive finding on novelty, the AC did not find an inventive step. This was provided as a mere assertion, without explaining the specific features present in the proposed invention but absent in the prior art, to justify novelty, and how these features did not require a person skilled in the art to make use of an inventive step.
On the Single Judge’s decision, the DB stipulated that similarity in objectives or end products alone cannot establish lack of inventive step. Subsequently, the DB listed several features in the specification that differed from disclosures in D1 and D2. The DB further held that the Single Judge had also misinterpreted and incorrectly applied F. Hoffmann v. La Roche Ltd v Cipla Ltd., 2016 (65) PTC 1 (Del),[5] which had laid down a five-step test for ascertaining obviousness and inventive step. The Single Judge had, however, bypassed the initial Steps 1–3, such as identifying the person skilled in the art or the inventive concept of the prior art, and started from Step 4 instead. Consequently, the DB held that the Single Judge had erred in the analysis of inventive step.
On the contention under Section 3(d), the DB assessed the findings of the AC[6] and the Single Judge.[7] The DB rejected these on two grounds. First, the AC and the Single Judge had not provided sufficient evidence to prove that the process claimed was a “known process”. Second, the DB noted that the invention would produce magnesium sulphate and activated carbon, which aren’t outcomes of D1 or D2. Therefore, the objection under Section 3(d) was considered incorrect.
The impugned order of the AC and decision of the Single Judge were set aside, the matter was remanded to the Patent Office, and consideration was restricted to objections under Section 25(1)(e) read with Section 2(1)(ja) of the Act. The objection under Section 3(d), as iterated earlier, was rejected.
The decision of the DB is important as it reinforced the principle of reasoned and speaking orders in pre-grant opposition proceedings. The Court emphasised how application of mind, especially on the part of examiners, is critical for the scrutiny of patent applications.
[1] 2025 DHC 8824-DB.
[2] “Claim 1. A process (100) for recovering potassium sulphate and other value added product from distillery spent wash, said process comprising: a. removing (102) high molecular weight organic compounds from the spent wash to obtain a first liquid fraction; b. concentrating (104) the first liquid fraction to obtain a first solid fraction; c. subjecting the first solid fraction to thermal decomposition (106) to obtain a second solid fraction; d. dissolving (108) the second solid fraction in a solvent to obtain a second liquid fraction; and e. recovering (110) potassium sulphate from the second liquid fraction.”
[3] US 20180257945A1 published 13 September 2018.
[4] Indian Standard IS: 8032-1976 (reaffirmed 2003); “GUIDE FOR TREATMENT OF DISTILLERY EFFLUENTS”, published by Bureau of Indian Standards in August 1976.
[5] The test of obviousness provided in this decision is as follows:
“Step No.1 To identify an ordinary person skilled in the art.
Step No.2 To identify the inventive concept embodied in the patent.
Step No.3 To impute to a normal skilled but unimaginative ordinary person skilled in the art what was common general knowledge in the art at the priority date.
Step No.4 To identify the differences, if any, between the matter cited and the alleged invention and ascertain whether the differences are ordinary application of law or involve various different steps requiring multiple, theoretical and practical applications.
Step No.5 To decide whether those differences, viewed in the knowledge of alleged invention, constituted steps which would have been obvious to the ordinary person skilled in the art and rule out a hindside approach.”
[6] “(iv)The office is in the same opinion with the opponent view on Sec. 25 (1) (f) i.e. “the subject matter of the impugned Application is not patentable under Section 3(d) of the Act”. The applicant argues that, as the claims of impugned application are Novel, does not fall within the ambit of section 3(d). But, as the process of the impugned application does not involve any new reactant nor results in a new product, and hence, the claims of impugned application are not allowable u/s 3(d) of The Patent Act 1970.”
[7] “14. A perusal of the cited prior art documents, D1 and D2, would demonstrate that the processes used in the subject invention are nothing more than a mere use of a combination of known processes. All the processes that are a part of the claims of the subject patent application are disclosed in the cited prior art documents, D1 and D2. Further, the appellant is not using any new reactant in the said processes, nor is the final process resulting in the creation of a new product. The end product in all the prior art documents as well as the subject patent application is the same, Potassium Sulphate.”
