2025 Supreme(Online)(Del) 48438

Amit Bansal, J
Crystal Crop Protection Limited – Appellant
Versus
Safex Chemicals India Limited – Respondent
I.A. 5255/2024 IN CS(COMM) 196/2024|CC(COMM) 28/2024

In patent infringement, independent claims and prosecution history define the inventive scope. If a patentee incorporates a feature in its independent claims to address a specific technical problem, that feature is deemed essential, and omission of such an element prevents a finding of infringement under the doctrine of equivalents.

Headnote:(A) Patents Act, 1970 - Order XXXIX Rules 1 and 2 of the Code of Civil Procedure, 1908 - Suit for permanent injunction against patent infringement - Determining 'essential features' of an invention - Court must examine complete specification, claims, and prosecution history - Principle of 'Doctrine of Equivalents' applies where there is no 'literal infringement' - Court refers to three-fold test for equivalence: i) does the variant achieve the same result in substantially the same way; ii) would it be obvious to a person skilled in the art; iii) did the patentee intend strict compliance as an essential requirement. (Paras 12, 13, 16, 19)

(B) Patent Infringement - Doctrine of Equivalents - Effect of inclusion of elements in independent claims - Once a feature is claimed as part of the solution to a problem, it is considered an essential element - Plaintiff is estopped from contending that an element of the independent claim is non-essential or optional through argument-based estoppel from prosecution history. (Paras 33, 34, 44, 46)

Facts of the case:
The plaintiff, holder of a patent for a weedicidal formulation, filed for an interim injunction against the defendants alleging that their competing products infringed upon its patented composition. The defendants contested the suit, arguing that their product lacked a specific 'dyeing agent or pigment' which the plaintiff had expressly included in its independent claims as a component of the invention. The court examined whether this absence of a component in the defendant's product constituted an infringement via the doctrine of equivalents.

Findings of Court:
The court held that the dyeing agent or pigment performed a specific functional purpose identified in the patent specification, namely, visual assessment of the herbicide's effectiveness. By incorporating this into the independent claims and emphasizing its necessity during the prosecution and opposition, the plaintiff identified it as an essential feature for solving a specific technical problem. Given that the defendants' product lacked this essential element, the court found no prima facie case for infringement by equivalence.

Issues: Whether the dyeing agent or pigment constitutes an essential element of the suit patent, and whether the absence of this feature in the defendants' product precludes a finding of infringement under the doctrine of equivalents.

Ratio Decidendi: Where independent claims explicitly include a feature, and the patent specification highlights that feature as integral to solving a technical problem, that feature is essential. The plaintiff cannot deviate from the literal claims of the patent to expand its scope under the doctrine of equivalents when the omission of an essential element fundamentally changes the utility and inventive concept of the patented product.

Result: Application for interim injunction dismissed.