Tapas Chatterjee Vs. Assistant Controller of Patents and Designs

Guidelines for Assessing Inventive Step in Patent Appeals

Facts: This case involved a patent dispute centering around the process for recovery of potassium sulphate and other valuable products from distillery spent wash, ultimately leading towards a Zero Liquid Discharge (ZLD) system. The appellant, Tapas Chatterjee, applied for a patent for this process in 2019, aiming to address the issue of water pollution caused by alcohol distilleries. The invention was intended to recover potassium sulphate, magnesium sulphate, activated carbon, and other value-added products from effluent, with the additional benefit of ZLD, which meant no liquid effluent was discharged back into the environment. The Council of Scientific and Industrial Research (CSIR) filed a pre-grant opposition against this application, citing several provisions of the Patents Act, 1970.

Procedural Detail: After the application was filed, the Assistant Controller of Patents and Designs (AC) conducted the standard examination, including the First Examination Report and subsequent reply from the appellant. The AC then dealt with the pre-grant opposition by CSIR, which was based on multiple grounds under Section 25(1) of the Patents Act. The main objections were that the invention was not novel, lacked inventive step, was not patentable under Section 3(d), and the methodology was not sufficiently described.

The AC rejected the opposition regarding lack of novelty but upheld the challenges relating to inventive step and Section 3(d). Consequently, the patent application was refused. The appellant appealed to a Single Judge of the High Court of Delhi, who affirmed the Controller’s decision. The appellant then brought a Letters Patent Appeal before the Division Bench.

Dispute: The core of the dispute revolved around two primary legal issues: Whether the invention as claimed was non-patentable under Section 3(d) of the Patents Act on grounds of being a mere use of a known process? Whether the invention lacked an inventive step, i.e., it was obvious in light of prior art documents , as per Section 2(1)(ja) and Section 25(1)(e)? The respondents (CSIR) contended that all steps described by the appellant were already disclosed in prior arts individually or in combination, and did not present any technical advance or require inventive faculty?

Detailed Reasoning: The Division Bench delved deeply into the reasons given by the Assistant Controller and the Single Judge. It noted that although the Controller accepted that the subject invention was novel, he still found a lack of inventive step compared to prior arts D1 (US patent) and D2 (Indian Standard). According to the Controller and the Single Judge, the steps of the claimed process were standard chemical engineering procedures, and no aspect of the steps was sufficiently distinct to warrant patent protection. The Controller held that routine operations (like concentration, thermal decomposition, dissolution, recovery) were obvious.

However, the Division Bench identified that the reasoning of both the AC and the Single Judge was inadequate and did not reflect a detailed, independent analysis of the prior arts compared to the subject invention. The Bench emphasized the importance of the legal test for inventive step outlined in F. Hoffmann-La Roche Ltd v. Cipla Ltd., which includes identifying the “person skilled in the art,” identifying the inventive concept, assessing the general knowledge at the priority date, and recognizing the differences between prior art and the claimed invention.

The key legal finding was that the Controller had failed to articulate which specific features of the claimed invention were obvious, and simply concluded so without detailed comparison. The prior arts (D1 and D2) had different approaches, products, and processes compared to the claimed invention’s steps, especially regarding the various fractions and recovery steps described in the application, and the additional by-products (magnesium sulphate, activated carbon) which were not claimed outcomes in D1 or D2.

The Division Bench also clarified the application of Section 3(d): it will only apply if the invention is a mere use of a known process, which was not positively shown in this case, and Section 3(d) would not apply if the process yields a new product or uses a new reactant. Since the process resulted in value-added products not described in the prior arts, the invocation of Section 3(d) was incorrect. Ultimately, the approach of the Controller (mechanical and unsupported by explicit reasons) and the analysis of the Single Judge (which skipped essential steps in the Hoffmann test) were found deficient.

Decision: The Division Bench allowed the appeal. The orders of the Single Judge and the Assistant Controller rejecting the appellant’s patent application were set aside. The matter was remanded to CGPDTM (Controller General of Patents, Designs and Trade Marks) for fresh consideration, specifically to reconsider the inventive step objection under Section 25(1)(e) read with Section 2(1)(ja), based strictly on the principles laid down in Hoffmann and the present judgment. The Bench unequivocally rejected the Section 3(d) objection raised by CSIR, stating there was no material basis for treating the process as a mere use of a known process. The adjudicating authority was directed to render a well-reasoned decision post-hearing, limited to the material already on record, and both parties were allowed to supplement their written submissions.

Case Title: Tapas Chatterjee Vs. Assistant Controller of Patents and Designs & Anr.

Order Date: 6 October 2025

Case Number: LPA 836/2023

Neutral Citation: 2025:DHC:8824-DB

Name of Court: High Court of Delhi at New Delhi

Hon’ble Judges: Justice C. Hari Shankar, Justice Ajay Digpaul

Disclaimer: The information shared here is intended to serve the public interest by offering insights and perspectives. However, readers are advised to exercise their own discretion when interpreting and applying this information. The content herein is subjective and may contain errors in perception, interpretation, and presentation.

Written By: Advocate Ajay Amitabh Suman, IP Adjutor [Patent and Trademark Attorney], High Court of Delhi