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Delhi High Court Sets Precedent on Product-by-Process Patents, Rejecting Limiting Effect of Process Terms in Infringement Cases

New Delhi: In a significant ruling set to shape patent jurisprudence in India, the High Court of Delhi, comprising Justices Yashwant Varma and Dharmesh Sharma , has clarified the scope and interpretation of product-by-process claims, particularly in the context of infringement analysis. The court overturned a Single Judge's order that had held such claims were limited to the specific manufacturing process described, stating that if the underlying product is novel and inventive, it is the product itself that is protected, irrespective of the process used by an alleged infringer.

The judgment, delivered on February 7, 2024 (with arguments concluded on November 2, 2023), arose from appeals filed by Vifor (International) Limited and another against an order dated July 24, 2023, passed by a Single Judge. The Single Judge had refused interim injunction applications in several commercial suits filed by Vifor alleging infringement of its Indian Patent No. 221536 (IN'536), which covers Ferric Carboxymaltose (FCM), a widely used intravenous iron preparation. The core issue revolved around whether IN'536, claimed in a "product-by-process" format, provided protection to the product (FCM) itself or was limited to the specific process described in the claim.

The Dispute Over FCM and Patent Scope

Vifor , the patent holder, contended that IN'536 claimed a novel and inventive product, FCM, which was unknown in the prior art at the time of filing the patent application in 2003. They argued that the complexity of FCM's structure necessitated describing the product by referring to its manufacturing process in Claim 1 (using the phrase "obtainable from"), a common and accepted practice in patent drafting globally, particularly for complex chemical or biological products. They asserted that this description did not limit the claim's scope to the process alone, but merely served to define the novel product. Vifor highlighted that FCM had been granted an International Non-proprietary Name (INN) by the WHO, indicative of its novelty, and pointed to the EPO's validation of the corresponding European patent on the basis that the invention lay in the product's unique characteristics, not just the process. They also cited numerous prior interim injunctions and final decrees granted in their favor by Indian courts regarding the same patent.

The respondent companies – MSN Laboratories, Dr. Reddy 's Laboratories, and Corona Remedies – countered that IN'536 was purely a product-by-process claim, and as such, its protection was strictly limited to the specific process described. They argued that infringement could only occur if they used the identical process claimed in IN'536, which they denied, pointing to different oxidizing agents or starting materials used in their manufacturing methods. They relied heavily on the majority opinion in the US Federal Circuit case Abbott Laboratories v. Sandoz , which held that process terms in product-by-process claims are limiting for infringement analysis, distinct from their treatment for validity. They also argued that iron carbohydrate complexes were known in the prior art and that Vifor 's own prosecution history and statements in other litigation showed they understood IN'536 as limited by process.

Single Judge's Findings and Appeal

The Single Judge, in the impugned order, accepted the respondents' submissions. The court held that IN'536 was primarily a product-by-process claim and that the process terms defined in Claim 1 acted as limitations. Relying, in part, on a perceived inconsistency in how product claims must be described (by structure/composition vs. process), the Single Judge concluded that the patent's monopoly was "limited to the product obtained by the specific process in the claims." This interpretation meant that variations in the manufacturing process used by the respondents would preclude a finding of infringement, irrespective of whether the end product was identical to Vifor 's FCM.

Vifor challenged this interpretation on appeal, arguing the Single Judge misconstrued their submissions, misunderstood the nature and purpose of product-by-process claims, and erroneously applied foreign precedents while disregarding settled principles of claim construction and Indian patent law.

Delhi High Court's Analysis and Key Principles

The Division Bench undertook an extensive review of Indian and international jurisprudence on product-by-process claims, citing decisions from the EPO, UK courts ( Kirin Amgen , Hospira UK Limited ), US courts ( Scripps , Atlantic Thermoplastics , Abbott Laboratories ), and the Japanese Supreme Court, as well as guidelines from the IPO, EPO, and USPTO.

The court first corrected the Single Judge's premise that Vifor argued product-by-process claims were unknown in India, noting Vifor 's explicit pleading that such claims are an accepted practice to describe complex products.

Crucially, the court rejected the notion that a product claim must always be described by composition and structure, acknowledging the "rule of necessity" that allows complex, structurally indefinable products to be described by their manufacturing process. The court emphasized that such claims are fundamentally directed at a novel and inventive product , not merely a novel process. The process terms serve to define the product where structural definition is difficult or impossible.

The court then squarely addressed the core conflict: whether process terms in a product-by-process claim are limiting during infringement analysis. It observed that Section 48 of the Indian Patent Act distinguishes between product patents (preventing making, using, selling the product) and process patents (preventing using the process and products directly obtained by that process). The court found no basis in the Indian Act, particularly in Sections 64 and 107 which allow invalidity grounds (like lack of novelty) as a defence to infringement, to apply different standards of novelty or claim construction between patent grant and infringement.

Rejecting the majority view in Abbott Laboratories that process terms limit infringement scope, the court sided with the dissenting opinions in that case and the position in other jurisdictions, notably the Japanese Supreme Court. The court held: * A product-by-process claim is a hybrid aimed at a novel product whose attributes are explained via its manufacturing process. * Patentability hinges on the novelty of the product itself , not just the novelty of the process. A new process for an old product does not make the product patentable. * Claims must be construed consistently for both validity and infringement. To hold otherwise would create an "incongruous and anomalous situation" and propagating a "double standard approach." * If the product itself is novel and inventive (falling under Section 48(a)), describing it with process terms due to the "rule of necessity" does not downgrade it to merely a process claim limited by Section 48(b). * The phrase "obtainable by" in a claim, as used in IN'536, is descriptive of a process that could produce the product, not necessarily limiting the claim to products only made by that specific process. This distinguishes it from "obtained by," which implies a direct result of the process.

The court criticized the Single Judge's conclusion that the invention resided solely in the process or starting materials, stating this overlooked Vifor 's contention (undisputed at the interim stage) that FCM itself was a novel compound. It also dismissed the respondents' arguments based on prosecution history estoppel and Vifor 's filing of divisional applications in the US and EPO as unpersuasive in the context of the legal principles established.

Conclusion and Implications

The Delhi High Court allowed the appeals, setting aside the Single Judge's order. While the court did not grant an interim injunction itself (as the patent expired in October 2023), it directed the pending suits to proceed based on the legal position it has enunciated. The court clarified that its ruling clarifies the principles governing product-by-process claims and does not preclude the respondents from raising other objections or defences regarding the patent's validity during the trial.

This judgment is a landmark clarification, affirming that product-by-process claims can provide broad protection to novel products in India, aligning Indian law more closely with the approach taken by the EPO and others, and rejecting the restrictive interpretation favored by the Abbott Laboratories majority. It provides much-needed clarity for patentees, particularly in chemical and pharmaceutical sectors, regarding the scope of protection afforded by such claims against potential infringers using alternative manufacturing routes to produce the same novel product.

The court's emphasis on consistent claim construction for both validity and infringement underscores a fundamental principle of patent law and prevents patentees from being trapped by the descriptive language necessitated by the complexity of their inventions.