Guidelines for Assessing Inventive Step in Patent Appeals

Executive Summary

This case involved a patent dispute over a process for recovery of potassium sulphate and other valuable products from distillery spent wash, aiming for a Zero Liquid Discharge (ZLD) system. The Assistant Controller of Patents and Designs (AC) refused the application on grounds of inventive step and Section 3(d). The Single Judge affirmed. The Division Bench remanded the matter to the Controller for a fresh, reasoned consideration limited to the record and allowed the appeal, rejecting the Section 3(d) objection.

Facts

The appellant, Tapas Chatterjee, applied for a patent in 2019 for a process to treat distillery spent wash and recover potassium sulphate, magnesium sulphate, activated carbon and other value-added products, while achieving Zero Liquid Discharge (ZLD). The Council of Scientific and Industrial Research (CSIR) filed a pre-grant opposition under provisions of the Patents Act, 1970.

Procedural History

1. Filing and Examination

   Application filed in 2019. Assistant Controller conducted the standard examination, issued a First Examination Report, and considered the appellant’s replies.

2. Pre-grant Opposition

   CSIR filed a pre-grant opposition under Section 25(1) raising multiple grounds including lack of novelty, lack of inventive step, Section 3(d) objections and insufficiency of disclosure.

3. Controller Decision

   The Assistant Controller rejected novelty objections but upheld inventive step and Section 3(d), refusing the patent application.

4. High Court — Single Judge

   The appellant appealed to the Single Judge of the High Court of Delhi; the Single Judge affirmed the Controller’s decision.

5. Division Bench Appeal

   The appellant filed a Letters Patent Appeal (LPA). The Division Bench allowed the appeal, set aside previous orders and remanded the matter to the Controller for fresh consideration.

Core Dispute and Legal Issues

The dispute centered on two principal legal questions:

• Section 3(d) applicability: Whether the claimed process was a mere use of a known process and therefore non-patentable under Section 3(d).
• Inventive step / obviousness: Whether the invention lacked an inventive step in light of prior art (Sections 2(1)(ja) and 25(1)(e)), particularly D1 (US patent) and D2 (Indian standard).

Detailed Reasoning

The Division Bench examined the Assistant Controller’s and the Single Judge’s reasoning in detail. While the Controller conceded novelty, he found lack of inventive step by comparing the claimed steps to prior arts D1 and D2 and treating routine chemical engineering operations as obvious.

Analysis of Prior Art

The Bench found the Controller’s analysis deficient because it did not identify with specificity which features were obvious nor did it perform a detailed point-by-point comparison between the prior arts and the claimed invention. The prior arts had different approaches, products and processes and did not disclose the combination of recovery steps and additional by-products claimed in the application.

Application of the Hoffmann-La Roche Test

The Bench reiterated the legal test for inventive step from F. Hoffmann-La Roche Ltd v. Cipla Ltd.:

1. Identify the person skilled in the art.
2. Identify the inventive concept of the claim in question.
3. Assess the state of general knowledge at the priority date.
4. Compare the differences between the prior art and the claimed invention and ask whether those differences would have been obvious.

The Division Bench concluded that the Controller and the Single Judge had not properly followed these steps, and thus their conclusions on inventive step were inadequately reasoned.

Application of Section 3(d)

The Bench clarified that Section 3(d) applies only if an invention is shown to be a mere use of a known process. It will not apply where the process yields a new product or uses a new reactant. Since the claimed process resulted in value-added products not present in the prior arts, the invocation of Section 3(d) was incorrect.

Decision

The Division Bench allowed the appeal, set aside the orders of the Single Judge and Assistant Controller, and remanded the matter to the Controller General of Patents, Designs and Trade Marks (CGPDTM) for fresh consideration limited to the material on record. The Court explicitly rejected the Section 3(d) objection and directed the Controller to re-evaluate inventive step following the Hoffmann test and to produce a well-reasoned decision after hearing the parties; both parties were permitted to supplement written submissions.

Practical Implications

The judgment emphasizes the necessity for adjudicating authorities and courts to provide clear, specific comparisons when rejecting inventive step. Routine or conclusory statements that standard operations render a process obvious will not suffice. The decision also narrows the application of Section 3(d) for processes that result in distinct or additional products.

Citations and Resources

Primary Citation: Tapas Chatterjee v. Assistant Controller of Patents and Designs & Anr., LPA 836/2023, Neutral Citation: 2025:DHC:8824-DB (Order dated 6 October 2025).

• Patents Act, 1970 (sections referenced including Section 2(1)(ja) and Section 3(d)).
• F. Hoffmann-La Roche Ltd. v. Cipla Ltd. — authority on inventive step test.
• Controller of Patents and Designs office guidance and examination reports.