FMC Corporation & Ors. Versus Natco Pharma Limited

Credible Challenge to Patent and Patent Infringement

Interim injunction refused in IN’645 despite admitted infringement; patent held highly vulnerable. The Court refused to grant an interim injunction, holding that the patent is highly vulnerable on multiple grounds: prior claiming by FMC’s own earlier patent IN 269104, lack of novelty and inventive step over cited prior art. Relying on the “credible challenge” principle laid down in F. Hoffmann-La Roche v. Cipla, Ericsson v. Lava, and Interdigital v. Xiaomi, the Court observed that only 19 days of patent life remained, Natco had already launched the product after obtaining regulatory approvals, and monetary compensation would suffice for the short remaining period.

Facts: The case revolves around a patent dispute in the agrochemical industry between FMC Corporation (an American company) along with its group companies (collectively called the plaintiffs) and Natco Pharma Limited (an Indian pharmaceutical and agrochemical company, referred to as the defendant). The plaintiffs own Indian Patent No. 298645 (called the suit patent), granted in 2018, which is titled “Method for Preparing N-Phenylpyrazole-1-Carboxamides”. This patent covers a process to make certain insecticides, and importantly, Claim 12 protects a specific chemical compound known as the Compound of Formula 3, which is an intermediate chemical used in that process. This intermediate is 2-amino-5-cyano-N,3-dimethylbenzamide – basically a building block chemical needed to produce the final insecticide called Cyantraniliprole.

The plaintiffs discovered that Natco was manufacturing and selling an insecticide product called Cyantraniliprole 10.26% OD (Oil Dispersion) using this exact patented intermediate. Natco openly admitted in court that it was using this intermediate in its manufacturing process. The plaintiffs therefore filed this suit as a preventive (quia timet) action, meaning they wanted to stop Natco even before huge damage was done, asking the court to stop Natco from using their patented intermediate. The patent is set to expire on 6 December 2025, so very little time was left when the judgment came.

There was already a long history of litigation between these two companies over related insecticides (Chlorantraniliprole and Cyantraniliprole). Earlier cases dealt with the process claims (Claims 1 to 11) of the very same patent, where courts had refused to grant interim injunctions to FMC because Natco’s process was found different enough. This time the fight was only about Claim 12 – the intermediate compound itself.

Procedural Detail: The suit was filed in 2024. The plaintiffs moved an application (I.A. 34151/2024) under Order 39 Rules 1 & 2 CPC for interim injunction. By the time the matter came up for hearing, Natco had already launched its product. On 1 August 2025 the court asked Natco to disclose its stock and sales, which Natco did through an affidavit in August 2025. The hearing took place over several dates and the judgment was delivered on 17 November 2025, just nineteen days before the patent was to expire.

Natco had earlier filed a revocation petition against the patent and had also taken regulatory approvals to sell the product. There were parallel commercial court cases in Chandigarh that were transferred to the Delhi High Court. The matter was therefore heard urgently because the patent life was almost over.

Dispute

The core dispute was very simple: Natco admitted it was using the exact chemical intermediate covered by Claim 12 of the patent to make Cyantraniliprole. FMC therefore said there is clear infringement, and since the patent is valid till 6 December 2025, Natco must be stopped immediately. Natco did not deny using the intermediate but argued that the patent itself is invalid on multiple grounds – lack of novelty, obviousness, prior claiming by FMC’s own earlier patent IN 269104, Section 3(d) (mere new form), Section 3(e) (mere admixture), and that the claim was too broad (Section 10, insufficient disclosure, etc.). Natco said it had filed a revocation petition, so it had “cleared the way” and the court should not grant injunction when the patent is vulnerable and has only days left.

FMC replied that Natco is a habitual infringer, they themselves have many patents around the molecule (evergreening allegation by Natco), and since infringement is admitted, injunction must follow.

Detailed Reasoning of the Court:  The court first noted that in patent interim injunction matters, once infringement is admitted or clear, the burden shifts to the defendant to show a credible challenge to the validity of the patent. If the challenge is credible (meaning the patent looks seriously vulnerable), injunction is normally refused. This principle comes from the Division Bench judgment in F. Hoffmann-La Roche Ltd. v. Zydus Lifesciences Ltd. 2024 SCC OnLine Del 8291 and several other cases like Interdigital v. Xiaomi, Nokia v. Oppo, and Telefonaktiebolaget Ericsson v. Lava International.

The court then examined each ground of invalidity:Prior Claiming / Double Patenting: Natco argued that the same intermediate was already claimed in FMC’s earlier patent IN 269104. The court studied both patents and found substantial overlap in the chemical structure and examples. The court held that there is a serious triable issue of prior claiming under Section 64(1)(f) because the intermediate in IN’645 is essentially mirrors what was disclosed in IN’104. The court relied on M/s. Surendra Lal Mahendra Kumar Jain HUF v. Sri Maruthi Industries and Avery Dennison Corporation v. Konti Continental to hold that when two patents by the same patentee claim substantially the same invention, the later patent is vulnerable.

Lack of Novelty (Section 64(1)(e)): Natco placed several prior art documents (D1 to D12) that disclosed similar benzamide compounds. The court found that D4 (WO 2003/015519) and D6 (WO 2004/067528) disclosed very close structures and the difference was only minor alkyl substitutions. The court said the challenge looks strong because the claim is broad and covers almost all alkyl substitutions.

Obviousness (Section 64(1)(f)): The court applied the Pozzoli test as approved in F. Hoffmann-La Roche v. Cipla (2016) 65 PTC 1 (Del) and found that a skilled person reading the prior arts together would find the specific intermediate obvious. The court noted the motive to arrive at the compound was clearly provided in the prior arts themselves.

Section 3(d) – Mere new form: The court held that the intermediate is a new form (alkyl derivative) of known compounds disclosed in prior art and FMC failed to file any comparative data showing enhanced efficacy. Following Novartis v. Union of India (2013) 6 SCC 1 and Hoffmann-La Roche v. Natco Pharma, the court said Section 3(d) applies with full force to intermediates also, and absence of data makes the claim vulnerable.

Section 3(e) – Mere admixture: The claim was to a single compound with provisos, but the court found the provisos were not sufficient to take it out of mere admixture, so this ground was not accepted.

Insufficient disclosure / inoperability (Section 64(1)(h) & Section 10): Natco argued the patent does not teach how to make compounds where R3 is other than methyl. The court found merit in the argument and said this is a serious issue.

Excessive claim breadth / Aggrieved person: Not pressed strongly.

After examining all prior arts and applying the law, the court concluded that the patent is highly vulnerable on multiple grounds – prior claiming, novelty, obviousness and Section 3(d). The court distinguished the Chinese revocation (which was on different grounds) and said Indian law on Section 3(d) is stricter.

The court heavily relied on the following key cases and explained them simply:F. Hoffmann-La Roche v. Cipla 2015 – If defendant raises credible challenge, no injunction even if infringement is clear.Telefonaktiebolaget Ericsson v. Lava – Detailed checklist for “vulnerable” patent.Interdigital v. Xiaomi 2024 – Short patent life is a strong factor against injunction.Nokia v. Oppo – Revocation petition + strong prior art = credible challenge.Avery Dennison v. Konti Continental – Overlapping claims by same patentee = vulnerable.Bristol Myers Squibb v. J.B. Chemicals – Balance of convenience tilts against injunction when patent life is ending.

The court noted that only 19 days of patent life were left, Natco had already launched after taking approvals, and huge stock would go waste if injunction was granted now. Irreparable injury was not made out because money damages can compensate for 19 days.

Decision:  The application I.A. 34151/2024 was dismissed. No interim injunction was granted. 

Case Title:FMC Corporation & Ors. Versus Natco Pharma Limited

Judgment Date: 17 November 2025 

Case Number: CS(COMM) 607/2024

Neutral Citation: 2025:DHC:10092 

Court: High Court of Delhi 

Hon'ble Judge: Ms. Justice Mini Pushkarna

Disclaimer: The information shared here is intended to serve the public interest by offering insights and perspectives. However, readers are advised to exercise their own discretion when interpreting and applying this information. The content herein is subjective and may contain errors in perception, interpretation, and presentation.

Written By: Advocate Ajay Amitabh Suman, IP Adjutor [Patent and Trademark Attorney], High Court of Delhi