Summary
In a patent infringement case, the Delhi High Court denied Crystal Crop Protection's request for an interim injunction against Safex Chemicals. The dispute in the case centred on a herbicidal formulation containing Clodinafop, Metribuzin, and a dyeing agent. The Court held that the dye was an essential claim element and that Safex’s dye-free products did not infringe, even by equivalence. It also invoked prosecution history estoppel, noting that Crystal’s own claim amendments precluded a broad claim interpretation.
In a patent infringement suit between agrochemical rivals, Crystal Crop Protection Limited (“Crystal”) instituted a suit before the Delhi High Court seeking a permanent injunction against Safex Chemicals India Limited and its affiliates for alleged infringement of Indian Patent No. 417213. The patent, titled “Weedicidal Formulation and Method of Manufacture thereof,” claimed a specific composition of herbicides for controlling weeds, particularly in wheat crops. The Court denied the interim injunction sought by Crystal, holding that no prima facie case of infringement had been established in view of the absence of a dyeing agent in the defendants’ products.
Background and Scope of the Suit Patent
The suit patent, granted on 9 January 2023, was based on an application filed in 2010 and claimed a homogeneous wettable powder formulation comprising Clodinafop Propargyl (9%) and Metribuzin (20%) in a 1:2.2 ratio, along with a surfactant, a safener, and a dyeing agent or pigment. The complete specification described the invention as offering synergistic herbicidal activity with low phytotoxicity, uniform application, and improved visual monitoring through color marking.
Crystal asserted in the case that its product ‘ACM-9’, incorporating the patented composition, had been launched commercially and was protected under the suit patent. It claimed to have discovered in January 2024 that Safex and its associated companies were manufacturing and selling products—‘Racer’, ‘Trophy’, and ‘Jodi No.1’—with identical active ingredients and formulation ratios. As per Crystal, laboratory testing showed that the herbicidal components and safener in the defendants’ products were identical to those claimed in the suit patent.
Crystal’s Position on Patent Infringement
Crystal submitted that the invention’s novelty lay in the synergistic combination of active ingredients in the claimed ratio, which offered improved efficacy and safety. It contended that the dyeing agent mentioned in the claims was merely an adjuvant, added optionally to facilitate visual assessment, and was not central to the inventive concept. On this basis, Crystal argued that the absence of a dye in the infringing products should not negate infringement, especially since the defendants had admitted to using the core herbicidal combination.
Relying on the ‘doctrine of equivalents’ and the ‘pith and marrow’ principle, Crystal argued that minor variations that did not alter the essential nature or function of the patented invention should be disregarded. Crystal also pointed out that the dye was not treated as an essential element in the claim construction and was included in the claims only to offer a complete picture of the preferred embodiments.
Defendants’ Dye Arguments
The defendants admitted to using Clodinafop and Metribuzin in the specified ratio but contended that their formulations excluded any dyeing agent or pigment. They argued that the dye was not merely a cosmetic additive but a functionally significant element that enabled visual detection of sprayed areas and addressed key problems identified in the prior art.
Relying on the patent’s prosecution history, where the dyeing agent had originally been disclosed in dependent claims but was later moved to the independent claims during prosecution, the Defendants argued that the dyeing agent was essential to the claimed invention. The defendants also submitted that Crystal had differentiated its invention from prior art documents during post-grant opposition proceedings by emphasizing the presence of the dye as a distinguishing feature.
Court’s Analysis: Infringement, Equivalence and Estoppel
The Court considered whether the dyeing agent or pigment constituted an essential feature of the invention and whether its omission precluded a finding of infringement, either literal or by equivalence. It observed that under established principles of patent law, all elements residing in an independent claim must be presumed essential unless expressly disclaimed or demonstrated otherwise. It also noted that the Manual of Patent Office Practice and Procedure, 2019, and international jurisprudence required all essential technical features to be included in independent claims.
After reviewing the specification and other documents, the Court stated that the dyeing agent, having been elevated to the independent claims and having been described as solving a specific problem in the prior art, could not be treated as incidental. It observed that Crystal had relied on the dye to overcome objections during prosecution and to distinguish its invention from prior publications. These actions, according to the Court, gave rise to prosecution history estoppel, which prevented Crystal from asserting a broader claim scope at the infringement stage.
The Actavis Test
Applying the test for infringement by equivalence from Actavis v. Eli Lilly, the Court considered three questions: whether the variant achieved substantially the same result in substantially the same way; whether it would be obvious to a skilled person that it did; and whether the patentee intended strict compliance with the literal wording of the claim. The Court concluded that the first requirement had not been satisfied, since the dye served a specific functional purpose that could not be achieved by the defendants’ products in its absence. Consequently, the second and third questions were not examined.
The Court distinguished the decisions relied upon by Crystal, including Sotefin SA v. Indraprastha Cancer Society, UPL Ltd. v. Pradeep Sharma, and SNPC Machines v. Vishal Choudhary, noting that in each case, the omitted elements had not been found to be functionally essential or tied to the inventive concept. In contrast, in the present case, as per the court, the dyeing agent directly contributed to the core solution disclosed in the suit patent.
Patent Validity
A counterclaim challenging the validity of the suit patent was also filed by the defendants, raising questions of novelty and inventive step. However, the Court declined to rule on the validity of the patent at the interim stage, holding that the issue warranted consideration at trial.
Injunction Denial
Based on its analysis, the Court stated that Crystal had failed to make out a prima facie case of patent infringement, and refused to grant an interim injunction. However, the Court directed the defendants to maintain half-yearly accounts of the manufacture and sale of the impugned products.
Citation: Crystal Crop Protection Ltd. v. Safex Chemicals India Ltd. & Ors., CS(COMM) 196/2024 & CC(COMM) 28/2024, I.A. 5255/2024 (Del. High Ct. May 7, 2025). Available at: http://indiankanoon.org/doc/22603777/, Visited on: 19/05/2025.
