Delhi High Court Denies FMC Injunction, Upholds 'Gillette Defence' in Patent Showdown with Natco

In a significant ruling with far-reaching implications for patent litigation in India, the Delhi High Court has dismissed an application by agrochemical giant FMC Corporation for an interim injunction against Natco Pharma Limited. Justice Mini Pushkarna's detailed judgment affirms that a credible challenge to a patent's validity, particularly based on prior claiming and the 'Gillette Defence', can defeat a plea for interim relief, even for a registered patent nearing its expiry.

---

Case Background: A Dispute Over a Chemical Building Block

The legal battle centered on Natco's insecticidal product "Cyantraniliprole 10.26% OD." FMC Corporation alleged that Natco's manufacturing process infringed upon Claim 12 of its Indian Patent No. 298645 (IN'645), which is set to expire on December 6, 2025. This specific claim protects a chemical intermediate—a compound used as a building block in the synthesis of the final active ingredient, Cyantraniliprole.

FMC argued that as the patentee, it was entitled to an injunction to prevent irreparable harm and protect its exclusive rights during the patent's final year. However, Natco mounted a robust counter-offensive, asserting that Claim 12 of the IN'645 patent was invalid and that it was merely practicing what was already in the public domain.

The Core of the Defence: Prior Art and Credible Challenge

Natco's defence rested on several key pillars, primarily arguing that the invention claimed in IN'645 was not new. The company had preemptively filed a revocation petition for Claim 12 even before FMC initiated the infringement suit, demonstrating a bona fide challenge to the patent's validity.

The court found this challenge to be not just procedural but substantively credible. In its analysis, the bench reiterated a cornerstone principle of patent law, citing precedents like F. Hoffmann-La Roche Ltd. v. Cipl Ltd. : "...registration of a patent per se does not entitle a party to an injunction when a credible challenge has been raised to the patent, and that there is no presumption of a validity of a patent.” This statement underscores that at the interim stage, the defendant does not need to definitively prove invalidity but merely demonstrate that the patent is vulnerable and faces a serious question to be tried.

Unpacking the 'Gillette Defence' and Prior Claiming

The crux of Natco's successful argument was the 'Gillette Defence,' which posits that if a defendant is practicing technology or knowledge from an earlier, expired patent, they cannot be held liable for infringing a later one. Natco contended that the specific chemical intermediate covered by Claim 12 of FMC's IN'645 patent was already disclosed and claimed in another, earlier patent held by FMC itself—Indian Patent No. 269104 (IN'104), which has since expired.

The court meticulously undertook a claim-to-claim comparison and reached a critical finding: "On a claim to claim comparison, the court found that the intermediate compound in Claim 12 of the IN'645 Patent was specifically claimed in the IN'104 Patent."

This finding was pivotal. FMC had attempted to argue that IN'104 could not be considered 'prior art' because it was published in 2008, after the 2004 priority date of the IN'645 patent. However, the court rejected this, clarifying a crucial point of law regarding divisional applications. Since IN'104 was a divisional application, it retained the original priority date of its parent application, which was January 22, 2002—well before the priority date of the IN'645 patent. This established IN'104 as valid prior art for the purpose of an invalidity challenge based on prior claiming under Section 64(1)(a) of the Patents Act, 1970.

The court held that for determining anticipation by prior claiming, it is the 'priority date' that matters, not the 'publication date.'

The Genus vs. Species Conundrum

The judgment further delved into the complex relationship between 'genus' and 'species' patents. The court prima facie accepted Natco's characterization of IN'104 as a 'species' patent (claiming specific, narrowly defined compounds) and IN'645 as a later 'genus' patent (claiming a broader class of compounds that encompassed the earlier species).

The court found that all three specific compounds claimed in the prior (and expired) IN'104 patent were also covered under the broader Markush structure of Claim 12 in the IN'645 patent. This overlap was fatal to FMC's case for an injunction. The judgment highlighted the legal principle that a specific disclosure in prior art anticipates and invalidates a later, broader generic claim. To allow otherwise, the court reasoned, would effectively permit "evergreening"—an impermissible extension of a patent monopoly beyond the statutory 20-year term through subsequent, broader patenting of the same core invention.

"Since the key intermediate in Claim 12 of IN'645 was already claimed in FMC's earlier patent IN'104, which has expired, the court held that Natco's Gillette defence was prima facie valid," the court concluded. By manufacturing the intermediate, Natco was simply practicing an invention that had fallen into the public domain upon the expiry of the IN'104 patent.

Implications for Patent Litigants and Legal Strategy

This ruling serves as a powerful reminder for both patentees and potential challengers in the Indian legal landscape:

1. The Power of a Credible Challenge: A well-researched and substantiated challenge to a patent's validity, filed proactively, can be the most effective shield against an interim injunction. Defendants who have "cleared the way" by initiating revocation proceedings stand on much stronger footing.

2. Priority Date is Paramount: The judgment reinforces the critical importance of the priority date over the publication date in disputes involving prior claiming, especially in the context of divisional patent applications.

3. Scrutiny of Patent Portfolios: Companies with overlapping patent portfolios, particularly those involving genus-species relationships, must be wary. This decision shows that courts will scrutinize such portfolios for attempts at evergreening or re-monopolization and will not hesitate to deny equitable relief if a later patent appears to improperly extend the life of an earlier one.

4. The 'Gillette Defence' Remains Formidable: This case is a textbook example of the successful application of the Gillette Defence. It highlights the necessity for accused infringers to conduct thorough prior art searches, including within the patentee's own portfolio, to identify expired patents that may cover the allegedly infringing product or process.

Concluding that FMC had failed to establish a prima facie case and that the balance of convenience favored Natco, which had already secured regulatory approvals and commenced manufacturing, the Delhi High Court dismissed FMC's application, allowing Natco to continue its commercial activities pending the final outcome of the suit.