FMC Corporation & Ors. Vs Natco Pharma Limited, order dated 05.12.2022, case number FAO(OS) (COMM) 301/2022, neutral citation 2022/DHC/005311, High Court of Delhi at New Delhi, Hon'ble Mr Justice Vibhu Bakhru and Hon'ble Mr Justice Amit Mahajan.
The case revolves around a patent infringement dispute in the agrochemical sector where FMC Corporation, along with its subsidiaries FMC Agro Singapore Pte Ltd and FMC India Pvt Ltd, collectively engaged in producing and selling agrochemicals for crop enhancement and pest control, alleged that Natco Pharma Limited, a vertically integrated pharmaceutical company focused on developing, manufacturing, and marketing finished dosage formulations and active pharmaceutical ingredients, was infringing their process patent IN 298645 titled "Method for Preparing N-Phenylpyrazole-1-Carboxamides" for manufacturing Chlorantraniliprole (CTPR), an anthranilic diamide insecticide; the patent, originally granted to E.I. Du Pont De Nemours and Company on 09.07.2018 under Section 43 of the Patents Act, 1970, was assigned to FMC effective from 01.11.2017 via a confirmatory agreement dated 01.05.2018, with a filing date of 11.05.2007 in India, international application on 06.12.2005, and priority from 07.12.2004, expiring on 06.12.2025.
Factually, FMC discovered Natco's synthesis of CTPR through an Environmental Management Plan document submitted by Natco to the Andhra Pradesh Pollution Control Board and Natco's own patent application PCT/IN2019/050321 claiming priority from Indian Application 201841015241, which disclosed a preparation method for CTPR that FMC claimed was equivalent to their patented process involving combining a pyrazole carboxylic acid (Formula 2), an aniline compound (Formula 3), and sulfonyl chloride to form CTPR, asserting infringement of claims 1, 5-8, and 11 based on the doctrine of equivalents since both processes relied on activating the pyrazole carboxylic acid to react with the aniline to produce CTPR, transforming the same reactants into the same product.
Procedurally, this was part of a broader litigation history where FMC had previously sued Natco in CS(COMM) 611/2019 for infringing patents IN 207307 and IN 213332 related to CTPR, and in CS(COMM) 167/2021 for IN 207307 and IN 215218, with IN 204978 (a Markush claim covering CTPR) expiring on 21.03.2021; in response to Natco's notice dated 27.04.2022 under Section 105 of the Patents Act asserting non-infringement of IN 645, FMC replied on 02.05.2022 seeking more details and promptly filed the infringement suit CS(COMM) 349/2022 on 03.05.2022, while Natco preemptively filed CS(COMM) 295/2022 for a declaration of non-infringement, with notice issued on 06.05.2022; the suit was listed on 23.05.2022 where Natco stated it would launch CTPR post-expiry of IN 307 and IN 332 on 13.08.2022 using a non-infringing process, leading FMC to seek an interim injunction under Order XXXIX Rules 1 and 2 via IA 8130/2022, which the Single Judge rejected on 19.09.2022, prompting this intra-court appeal.
The core dispute centered on whether Natco's process, which used thionyl chloride to first convert the pyrazole carboxylic acid into an acid chloride before reacting it with the aniline in a two-step, two-reactor method yielding lower output but no toxic by-products, infringed FMC's single-step process using sulfonyl chloride as the activating reagent under the doctrine of equivalents, despite no literal infringement, as FMC argued the processes were substantially equivalent in function (stoichiometric activation of carboxylic acid), way (coupling intermediates), and result (CTPR production), while Natco contended the processes were distinct, with sulfonyl chloride forming a mixed anhydride versus thionyl chloride forming an acid chloride, and emphasized element-to-element comparison for process patents where monopoly is limited to the claimed method.
The core reasons for the court's analysis stemmed from the need to interpret the scope of process patent claims under Sections 48 and 64 of the Patents Act, 1970, applying purposive construction as per Ravi Kamal Bali v Kala Tech, 2008 (110) Bom LR 1850, and considering the doctrine of equivalents from US precedents like Graver Tank & Mfg Co v Linde Air Products Co, 339 US 605 (1950), to prevent minor variations from defeating patent rights, but adapting it to Indian law where process patents protect only the method, not the product, and requiring a triple test of function-way-result while assessing essentiality of elements; to resolve technical complexities, the court appointed scientific advisors under Section 115 of the Patents Act—Dr Gopakumar Nair and Prof Bhalchandra Mahadeo Bhanage (replacing Dr Raghavan Soman)—on 29.07.2022 and 08.08.2022, with terms of reference from both parties addressing whether intermediates were prior art (e.g., in IN 215218, IN 284017, WO 518), differences between thionyl and sulfonyl chlorides (inorganic vs organic, physical/chemical properties), presence of methane sulfonic acid impurity in Natco's product, and if the processes were distinct or equivalent, with advisors concluding the intermediates were disclosed in prior art, thionyl chloride differed from sulfonyl chloride, no methane sulfonic acid impurity in Natco's dossier, the processes were distinct (Natco's two-step vs FMC's one-pot), sulfonyl chloride forms mixed anhydride while thionyl forms acid chloride not being a mixed anhydride, and Natco's process requires reacting acid with thionyl first then acid chloride with aniline, unlike FMC's simultaneous combination.
In discussing the judgment, the Division Bench upheld the Single Judge's prima facie finding of no infringement, respecting the advisors' unchallenged opinions as per Martin F D'Souza v Mohd Ishfaq, (2009) 3 SCC 1, noting sulfonyl chloride's essentiality from the patent's description and claims where it was specified as the preferred reagent (e.g., methanesulfonyl chloride), and highlighting process differences: FMC's one-pot method mixes acid, aniline, and sulfonyl chloride simultaneously, while Natco's sequential two-reactor approach uses thionyl chloride for acid chloride formation without sulfonyl chloride, yielding different intermediates and by-products.
The court referred to international precedents like Kirin-Amgen Inc v Hoechst Marion Roussel Ltd, [2004] UKHL 46 (UK) emphasizing claim limits, Improver Corp v Remington Consumer Products Ltd, [1990] FSR 181 (UK) on variants, and US cases like Warner-Jenkinson Co v Hilton Davis Chemical Co, 520 US 17 (1997) on equivalents, but stressed in Indian context from Raj Parkash v Mangat Ram Chowdhry, AIR 1978 Del 1, that pith and marrow doctrine applies only to non-essential variations, finding thionyl chloride's substitution not trivial given chemical distinctions and sequence changes.
Further citations included Avery Dennison Corp v Accutec Blades Inc, 45 F Supp 3d 1148 (CD Cal 2014) on process equivalents, and Indian cases like TVS Motor Co Ltd v Bajaj Auto Ltd, 2009 (40) PTC 689 (Mad) on triple test adaptation for processes, concluding Natco's method was not a subterfuge but a distinct alternative not falling within claim scope even under equivalents.
The decision dismissed the appeal, confirming no interim injunction, allowing Natco to proceed with its process post-expiry of prior patents, with the suit to proceed on merits.
The crucial legal principle settled is that for process patent infringement under the doctrine of equivalents in India, courts must conduct an element-to-element comparison to determine if substitutions are insubstantial, treating specified reagents like sulfonyl chloride as essential if integral to novelty and functionality, and limiting equivalents to prevent extension beyond claimed method, adapting the function-way-result test to emphasize sequence and intermediate differences in chemical processes, thereby balancing patentee rights against public interest in alternative innovations.
Written By: Advocate Ajay Amitabh Suman, IP Adjutor [Patent and Trademark Attorney], High Court of Delhi
Disclaimer: This information report is intended for informational purposes only and does not constitute legal advice.
