Synergy for herbicidal compositions must be established through comparative data demonstrating effect beyond mere substance aggregation.

The Appellant filed Indian Patent Application No. 2228/DEL/2011 for a "Herbicidal Composition for Field Crops," specifically a synergistic combination of Halosulfuron-methyl (10-15%) and Metribuzin (50-60%) for use in sugarcane.

Respondent Nos. 2 and 3 filed pre-grant oppositions under Section 25(1) of the Patents Act, 1970.

On March 28, 2023, the Controller (Respondent No. 1) issued an Impugned Order rejecting the application on grounds of lack of inventive step and non-patentability under Section 3(e).

During the appeal, Respondent No. 2 moved an application (I.A. 20715/2025) under Order XLI Rule 27 of the CPC to introduce eleven additional prior art documents from the US EPA and academic sources to further challenge patentability.

Whether additional documents not presented before the Controller can be admitted at the appellate stage under Order XLI Rule 27 of the CPC.

Whether the claimed herbicidal composition involves an "inventive step" under Section 2(1)(ja) in view of cited prior arts D1, D2, D5, and the newly admitted documents.

Whether the composition is a "mere admixture" barred under Section 3(e) of the Act.

The court applied Rule 6 of the Delhi High Court Intellectual Property Division (IPD) Rules, 2022, and Order XLI Rule 27 of the CPC regarding the admission of additional evidence, which allows such documents if required for the court to pronounce a satisfactory judgment.

Regarding patentability, the court applied Section 2(1)(ja) of the Patents Act, 1970, defining "inventive step" as a technical advance over existing knowledge that is non-obvious to a person skilled in the art (PSITA).

It further applied Section 3(e), which excludes from patentability any substance obtained by a mere admixture resulting only in the aggregation of properties, relying on the principle from *Best Agrolife Limited v. Deputy Controller of Patents* that synergy must be demonstrated through comparative data showing an effect beyond the sum of individual components.

The Court first allowed the additional documents, noting their high relevance to the technical determination of prior art and their necessity for a proper judgment.

Analyzing the merits, the Court found that prior art document D2 (WO 2009/015064 A2) explicitly disclosed a tank-mix of Halosulfuron-methyl and Metribuzin in a 1:3 ratio, which overlapped with the Appellant's claimed ranges.

Furthermore, the prior art GWN-9889 disclosed a composition with 11.2% Halosulfuron and 58.3% Metribuzin, nearly identical to the Appellant’s preferred 12/55% ratio.

The Court rejected the claim of "synergy" because the Appellant's own data in Table 1 showed that efficacy increased proportionally with the dosage of active ingredients (ai/ha) rather than as a result of the specific combination ratio itself.

Since the use of these two chemicals together was already known in the art for the same purpose (herbicidal control in crops), the Court held that a PSITA could have reached the invention through routine experimentation.

It held that the additional documents were admissible as they were essential for a comprehensive adjudication.

On the merits, the Court held that the Subject Application failed the test of inventive step under Section 2(1)(ja) due to existing disclosures in prior arts D2 and GWN-9889.

It further held that the composition was a "mere admixture" under Section 3(e) as the Appellant failed to provide clear comparative data at the time of filing to establish true synergistic effect.

No order as to costs was made.