Inventiveness Lies in the Simplicity of Process: Delhi High Court Sets Aside Rejection of Process Patent Under Sections 3(d) and 2(1)(ja)

"A mere reference to known objectives or reagents does not render an entire process 'known' under Section 3(d). The process must be shown to be the same in substance — which it is not." - On 6 October 2025, the Division Bench of the Delhi High Court comprising Justice C. Hari Shankar and Justice Ajay Digpaul delivered a significant judgment setting aside the rejection of a process patent application for recovery of potassium sulphate and other valuable products from distillery spent wash. The Court held that the invocation of both Section 3(d) and Section 2(1)(ja) of the Patents Act, 1970 by the Assistant Controller and upheld by a Single Judge, was legally untenable due to fundamental errors in reasoning, insufficient comparative analysis, and mechanical application of patent law principles.

“The analysis of inventive step must begin with identifying the skilled person and inventive concept — skipping these steps leads to flawed conclusions.”

Tapas Chatterjee, the appellant, had filed a process patent application (No. 201911036748) on 12 September 2019 for a method titled “Recovery of Potassium Sulphate and other valuable products from Spent Wash leading to ZLD (Zero Liquid Discharge) System.” The objective was to treat molasses-based alcohol distillery effluent (spent wash) through a stepwise chemical process to recover valuable by-products such as potassium sulphate, magnesium sulphate, activated carbon, water, and high molecular weight organic compounds usable as fuel or cattle feed.

A pre-grant opposition was filed by CSIR (Council of Scientific and Industrial Research), asserting the claims lacked novelty and inventive step, and that they were barred by Section 3(d) as a mere aggregation of known processes. The Assistant Controller (AC) rejected the patent on 28 December 2021, not for lack of novelty, but on the dual grounds of:

• Lack of inventive step under Section 25(1)(e) read with Section 2(1)(ja)

• Non-patentability under Section 25(1)(f) read with Section 3(d)

This rejection was upheld by a Single Judge of the Delhi High Court on 10 March 2023. Aggrieved, the appellant preferred the present Letters Patent Appeal.

Whether the process patent was rightly rejected under Section 3(d) as a “mere use of known process”?

The Court categorically held that Section 3(d) was wrongly invoked. While the AC and Single Judge found the process to be “known” and lacking novelty because the final product—potassium sulphate—was not new, the Division Bench disagreed:

“The learned Single Judge, as well as the AC, have failed to notice that the process that the appellant desires to patent was not merely for recovering potassium sulphate, but also for recovering other valuable products… There is, in D1 as well as D2, no reference to either magnesium sulphate or high molecular weight organic compounds usable as cattle feed or fuel.”

The Court clarified that under Section 3(d), the threshold inquiry must first establish whether the process is indeed “known” and then determine whether it yields a new product or employs a new reactant:

“In the present case, we are of the considered opinion that the subject process… is not rendered non-patentable by virtue of Section 3(d); firstly, because there are marked differences in the process… and, secondly, because it results in products which are not claimed outcomes of the processes envisaged in D1 and D2.”

Whether the invention lacked inventive step under Section 2(1)(ja) in view of prior art D1 and D2?

The Court found grave procedural and substantive errors in both the AC's and Single Judge’s analysis under Section 2(1)(ja). Criticizing the AC’s order as “laconic” and “mechanical,” the Court noted:

“There is not a whisper of explanation in the order of the AC as to how a person skilled in art would, by going through the prior art documents D1 to D4, individually or in combination, be in a position to arrive at the subject invention.”

Further, it found the Single Judge’s analysis to be flawed for beginning the Hoffmann-La Roche five-step inventive step test at Step 4 (differences), while entirely skipping Step 1 (identification of a person skilled in the art) and Step 2 (identification of the inventive concept). The Court reiterated:

“Skipping these foundational steps renders the entire analysis procedurally unsound.”

In its own analysis, the Court extensively compared the claimed invention to prior art D1 (US Patent Application 2018/0257945) and D2 (BIS Guide IS:8032-1976). It held that even superficially similar process components (like pyrolysis and thermal decomposition) differed significantly in sequence, reagents, products, and environmental outcomes.

“It cannot be said by any stretch of imagination that the processes set out in the claims in the subject application are obvious… Inventiveness may exist even in the manner in which a particular objective is achieved… Inventiveness resides, at times, in simplicity.”

• Section 3(d): The Bench unequivocally rejected the objection under Section 3(d), observing that neither D1 nor D2 described the specific process in its entirety, nor the recovery of additional products like magnesium sulphate or activated carbon. Thus, the process was not “known” and produced multiple valuable outputs—excluding the application of Section 3(d).

• Inventive Step (Section 2(1)(ja)): The Court faulted the reasoning of the AC and Single Judge for failing to conduct a structured comparative analysis or explain how the teachings of D1 and D2 could be combined to arrive at the claimed invention. It emphasized that without adherence to the Hoffmann test, the findings were unsustainable.

“A person skilled in the art, possessed of prior general knowledge, must be able to arrive at the invention from the prior art—yet no such reasoning was provided.”

• Remand with Restrictions: While rejecting the Section 3(d) bar outright, the Court remanded the matter to CGPDTM for a fresh decision limited to Section 25(1)(e) (inventive step), instructing that the decision must be rendered de novo, within 6 months, based strictly on existing materials, and in line with the Hoffmann framework.

The Delhi High Court’s judgment is a crucial precedent for process patent jurisprudence in India, particularly in clarifying the scope of Section 3(d) in process inventions and enforcing rigorous standards for determining inventive step. It highlights the judiciary’s insistence on reasoned, structured, and legally sound decision-making by patent authorities and lower courts.

“The order of the AC, in our view, was liable to be set aside even for the manner in which it came to be passed,” the Court observed, sending a strong message on procedural due process in intellectual property adjudication.

Date of Decision: 06 October 2025