Delhi High Court Analyses a Patent of Process Litigation Case on the Basis of the “Doctrine of Equivalence”

In the case of FMC Corporation & Ors. Vs. Natco Pharma, the Delhi High Court has dismissed FMC’s claim of permanent injunction against Natco to impede them from manufacturing the drug ‘Chlorantraniliprole’(CTPR). 

The suit patent registered by FMC Corporation claims a novel method for preparing anthranilic diamide-based pesticides in a total of 12 claims. In the abovementioned suit, the plaintiff FMC found that Natco was manufacturing CTPR with an allegedly similar process claimed in FMC’s patent.

The defendant before the injunction suit had two main counterclaims; first, inferring that the doctrine of equivalence must test “all elements” of the patent in its assessment for an infringement of a patent of process, meaning that each claim and element must be compared one by one; second and precisely the defendant argued that the scope of the independent claim of the patent under scrutiny is expressly limited to one specific combination of carboxylic acid with sulfonyl chloride as the reagent for the chemical compound resulting from the process, concluding that this was a combination they did not replicate within their own process.

The court concluded that the suit patent process and the Natco process are distinct and different; sulphonyl chloride and its combination with carboxylic acid as a reagent is an essential element of the patent, strictly determining its scope of protection. Hence, the application for a permanent injunction of Natco’s process was dismissed.

Such interpretation of the court sends a vital message for drafting and enforcing patents of process: it is essential to claim a process that is as broad as possible to avoid a too specific and narrow scope of protection within the patent application.