The Delhi High Court refused FMC Corporation\u2019s request for an interim injunction to restrain Natco Pharma from manufacturing or using the intermediate compound claimed in Claim 12 of Indian Patent No. 298645. The Court found that Natco had raised a credible prima facie challenge to the validity of Claim 12, both on the grounds of anticipation by prior claiming under Section 64(1)(a) and lack of novelty under Section 64(1)(e) of the Patents Act, 1970. In light of the credible invalidity challenge, the imminent expiry of the patent, and Natco\u2019s ongoing commercial manufacture, interim relief was declined.<\/p>\n
FMC Corporation and FMC IP Technology GmbH (\u201cFMC\u201d) are the patentees of Indian Patent No. 298645 (\u201cIN\u2019645\u201d), granted on 9 July 2018 and due to expire on 6 December 2025. IN\u2019645 contains twelve claims: Claims 1\u201311 of N\u2019645 relate to a process for preparing the insecticidal active ingredient Cyantraniliprole, while Claim 12 protects an intermediate compound, 2-amino-5-cyano-N,3-dimethylbenzamide. Natco Pharma Ltd. (\u201cNatco\u201d) developed and commercially launched an agricultural formulation, Cyantraniliprole 10.26% OD.<\/p>\n
The parties have been engaged in continuous patent litigation involving the Cyantraniliprole and Chlorantraniliprole patent families since 2022. Natco initially filed a declaratory suit seeking a declaration of non-infringement of Claims 1\u201311 of IN\u2019645 relating to the manufacture of Chlorantraniliprole. FMC responded with an infringement action, in which the interim injunction was refused. Natco later filed another declaratory suit seeking non-infringement of FMC\u2019s patent IN 277358 (\u201cIN\u2019358\u201d) concerning Cyantraniliprole 10.26% OD. Subsequently, Natco also filed a revocation petition challenging Claim 12 of IN\u2019645.<\/p>\n
In April 2025 Natco received the required regulatory approvals and commenced commercial manufacture of Cyantraniliprole 10.26% OD. Meanwhile, FMC instituted three additional suits in Chandigarh alleging infringement of Claim 12, which were later transferred to the Delhi High Court.<\/p>\n
Natco argued that FMC had constructed a \u201cpatent thicket\u201d of over 40 patents to evergreen Cyantraniliprole and its related compounds. It submitted that Claim 12 of IN\u2019645 was invalid because the intermediate had already been claimed in FMC\u2019s earlier patent IN\u2019104, which carries a priority date of 22 January 2002.<\/p>\n
Natco further submitted that WO\u2019226, the PCT application from which IN\u2019104 originated, disclosed and enabled the same class of intermediates, thereby defeating novelty under Section 64(1)(e). It invoked the Gillette defence, asserting that its manufacturing process merely practised expired prior art (IN\u2019104 and WO\u2019226), leaving no scope for infringement. Natco also stressed that it had \u201ccleared the way\u201d by filing a revocation petition before launching its product, and that the balance of convenience favoured it given its significant investments and the imminent expiry of IN\u2019645.<\/p>\n
FMC argued that Natco\u2019s acknowledgment of using the intermediate compound protected under Claim 12 established prima facie infringement under Section 48. FMC contended that IN\u2019104 could not qualify as prior art because its amended claims were published on 15 August 2008, well after the priority date of IN\u2019645 (7 December, 2004). FMC also argued that WO\u2019226 did not disclose or enable the specific intermediate of Claim 12, and therefore could not anticipate the suit patent.<\/p>\n
FMC submitted that interim relief was appropriate given the imminent expiry of the patent, Natco\u2019s launch during proceedings, and the narrow scope of relief sought (limited to the intermediate).<\/p>\n
The Court reiterated that, for the purposes of assessing prior art under Section 64(1)(a), the relevant date is the \u201cdate of priority\u201d, not the \u201cdate of publication\u201d. It noted that, as IN\u2019104 is a divisional of IN\u2019417, it automatically inherited the earlier priority date of 22 January 2002 and therefore constituted valid prior art against Claim 12 of IN\u2019645.<\/p>\n
On comparing the claims, the Court found that Formula 6 of Claim 1 in IN\u2019104 prima facie covered the same intermediate compound represented as Formula 3 in Claim 12 of IN\u2019645. The Court therefore observed that IN\u2019104 operated as a species claim, while Claim 12 functioned as its genus counterpart, making the suit patent vulnerable to anticipation by prior claiming.<\/p>\n
The Court noted that WO\u2019226 entered India as a national phase application and was granted as IN\u2019417, which was subsequently divided into two divisional patents, IN\u2019417 and IN\u2019104. It further observed that WO\u2019226 was published on 31 July 2003, a date earlier than the priority date of the suit patent. On a prima facie assessment, the Court found that the intermediate compound covered by Claim 12 of IN\u2019645 appeared to be disclosed in WO\u2019226. Consequently, Claim 12 was considered to be vulnerable to a validity challenge for anticipation under Section 64(1)(e).<\/p>\n
The Court accepted Natco\u2019s reliance on the Gillette Defence, noting that if a defendant\u2019s product or process is wholly within expired prior art, infringement does not arise. Since the Court had already held that the intermediate was prior claimed in IN\u2019104, which expired on 16 January 2023, Natco was entitled to practice the compound. The defence was therefore prima facie tenable.<\/p>\n
The Court found that Natco had \u201ccleared the way\u201d by filing a revocation petition and disclosing its product in earlier proceedings before commencing commercial manufacture. The Court noted that Natco had invested heavily in infrastructure and regulatory compliance and had been commercially manufacturing the product since April 2025. With IN\u2019645 due to expire in less than two months, any loss to FMC was compensable in damages, whereas an injunction would significantly prejudice Natco.<\/p>\n
The Court held that Natco had raised a prima facie credible challenge to the validity of Claim 12 under Sections 64(1)(a) and 64(1)(e), supported by the Gillette Defence and by its prior steps to clear the way. With the patent nearing expiry and Natco having already been in commercial production, the Court declined to grant interim relief. Natco was directed to continue disclosing details of the quantities and value of products manufactured and sold.<\/p>\n
The Court clarified that all findings were prima facie and confined to the adjudication of the interim injunction application, without prejudicing the final determination at trial.<\/p>\n