Every patent dispute, whether an infringement suit before the High Court or a revocation proceeding, ultimately turns on one question: what does the claim actually mean? A patent is a bargain in which the inventor discloses the invention to the public in exchange for a limited monopoly, and the claims are the part of the specification that defines the boundaries of that monopoly. Until those boundaries are fixed, a court cannot say whether a defendant’s product falls inside them, and cannot say whether the claim, read at its true breadth, is novel, inventive and sufficiently disclosed. Claim construction is therefore the foundation of both infringement and validity analysis, and in practice it is often the issue on which a case is won or lost.
India has no single statutory code on how claims are to be interpreted. The principles have been built up through decisions of the Supreme Court and the Delhi High Court, which has handled much of the country’s patent litigation. Those decisions have drawn heavily on English authority, while the most recent rulings insist that Indian claim construction must rest on Indian statutory text and not on borrowed European drafting conventions. This article sets out the statutory framework, the procedural setting in which claims are construed, the core interpretive principles, and the way recent decisions have refined them.
The Statutory Foundation
The Patents Act, 1970 says surprisingly little about how claims are to be read, but it fixes their function. Section 10(4)(c) requires that a complete specification end with a claim or claims defining the scope of the invention for which protection is claimed. Section 10(5) adds that the claims must relate to a single invention or a group of inventions forming a single inventive concept, must be clear and succinct, and must be fairly based on the matter disclosed in the specification. These provisions establish two propositions that run through the case law: the claims define the monopoly, and the claims must be anchored in what the specification actually discloses.
The Act is also notably silent on claim format. As the Division Bench of the Delhi High Court recently observed in Automat Industries Pvt. Ltd. v. Aquestia Limited, Section 7(1) requires only that an application be made in the prescribed form, which for the complete specification means the claims begin with the words “I/We claim” and appear on a separate page. Nothing in the Act requires claims to be divided into a “known” portion and a “characterised in that” portion, or to follow any particular structure. The drafter is free to choose how to define the invention, and the court must interpret whatever structure has been chosen.
Section 59 is the other statutory pillar. It restricts amendments so that an amended specification cannot claim or describe matter not in substance disclosed in the original, and every amended claim must fall wholly within the scope of a claim before amendment. This provision is why the prosecution history matters. Narrowing amendments and statements made to obtain grant leave a record, and, as the discussion of Crystal Crop below shows, courts now look at that record when deciding how far a claim can be stretched in litigation.
Where and How Claims Are Construed
Indian procedure has no separate pre-trial hearing devoted to claim construction of the kind known as a Markman hearing in the United States. As the WIPO International Guide to Patent Case Management for Judges explains in its India chapter, claim construction is handled as part of the trial, and disputes over the meaning of claims are framed as issues at the case management hearing. The High Court of Delhi Rules Governing Patent Suits, 2022 recommend that parties file a claim-construction brief before the case management hearing so that the court and the parties can identify early where the claims are actually in dispute.
In practice, claim construction also happens much earlier than trial. Because patent plaintiffs in India usually seek interim injunctions, courts are asked at the interlocutory stage to form a prima facie view of what the claims mean and whether the defendant’s product falls within them. Several of the most important recent decisions, including the Automat and Crystal Crop rulings discussed below, were rendered at precisely this stage. The consequence is that a misreading of a claim can decide the fate of a product launch long before any evidence is led.
Claims and Specification Read Together: Bishwanath Prasad
The foundational Indian authority is the Supreme Court’s decision in Bishwanath Prasad Radhey Shyam v. Hindustan Metal Industries, (1979) 2 SCC 511. Decided under the predecessor legislation to the present Act, the judgment holds that claims must be given an effective meaning and that the specification and the claims must be examined and construed together. The Court followed English precedent in reaching this conclusion. The WIPO guide notes that an earlier Bombay High Court view in Farbwerke Hoechst v. Munich Laboratories, AIR 1969 Bom 255, which treated the specification as relevant only where the claim was ambiguous, was effectively overruled by Bishwanath Prasad.
The practical effect is that Indian courts do not read claims in isolation. The description and drawings supply the technical context in which the words of the claim are to be understood, and a court construing a claim will look at the specification as a matter of course, not only when the claim is unclear. Bishwanath Prasad remains the case most frequently cited for this proposition, and it was relied on again by the Delhi High Court in 2026.
Purposive Construction: Roche v. Cipla
The leading modern authority on claim construction under the Patents Act, 1970 is the Division Bench decision in F. Hoffmann-La Roche Ltd. v. Cipla Ltd., 225 (2015) DLT 391 (DB), delivered by a bench of Justices Pradeep Nandrajog and Mukta Gupta. Roche held the patent for erlotinib hydrochloride, the lung cancer drug sold as Tarceva, and sued Cipla over its generic product Erlocip. The Division Bench held that Roche’s claim covered the erlotinib hydrochloride compound as such and not merely a single polymorphic form of it. Since Cipla’s product was one polymorphic form of that compound, it infringed.
For present purposes, the importance of the case lies in the method. The WIPO guide records that the Delhi High Court held that claims are to be given a purposive construction, drawing inspiration from the English House of Lords decision in Catnic Components Ltd. v. Hill & Smith Ltd. [1982] RPC 183. The Catnic approach asks how a person skilled in the art, with practical knowledge of the field, would understand the claim language. The question is whether such a person would read a particular word or phrase as an essential requirement of the invention, so that any variant falls outside the monopoly. Lord Diplock’s reasoning in Catnic was that no rational patentee would intend a limitation so narrow that a trivial variation, such as positioning a component a degree or two from the exact vertical, would let an imitator avoid the patent and take all the benefit of the invention.
Roche v. Cipla has since been treated as setting a two-stage framework, which later Division Bench decisions apply: first construe the claims, then compare the construed claims with the defendant’s product. The Division Bench’s decision in Canva Pty Ltd. v. RxPrism Health Systems, FAO(OS)(COMM) 211/2023, anchored its infringement analysis in this two-stage test and invoked Bishwanath Prasad to ensure the construction was not too narrow.
The English Backdrop and the Unresolved Question
Indian claim construction has tracked English law, and English law has itself moved. The Catnic principle was later formulated as the three “Improver” questions in Improver Corp. v. Remington Consumer Products Ltd. [1990] FSR 181, which the House of Lords approved in Kirin-Amgen Inc. v. Hoechst Marion Roussel Ltd. [2005] RPC 9. In Actavis UK Ltd. v. Eli Lilly and Co. [2017] UKSC 48, however, the UK Supreme Court departed from that line. It held that the earlier cases had conflated two separate questions, and it separated them. The court first asks whether the product infringes the claim as construed by a normal interpretation, which is itself purposive because the claim is read in its context and in light of common general knowledge. Only if it does not does the court ask whether the product infringes through an equivalent, applying a distinct test for equivalents.
The WIPO guide observes that, at the time it was written, no Indian judgment had squarely addressed this development, though it expected Indian courts to follow a similar course given their historical reliance on English precedent. More recent decisions show that this is beginning to happen. In Crystal Crop Protection Ltd. v. Safex Chemicals India Ltd., discussed below, the Delhi High Court applied the framework from Actavis when analysing equivalence, according to published commentary on the judgment.
Holistic Construction: The Automat Ruling of 2026
The most significant recent statement of principle is the Division Bench judgment in Automat Industries Pvt. Ltd. v. Aquestia Limited, FAO(OS)(COMM) 123/2025, decided on 5 January 2026. Aquestia sued Automat alleging that its Hydromat valves infringed Indian Patent No. 427050, titled “A Fluid Control Valve”. Claim 1 was drafted in the two-part form common in European practice: the elements preceding the words “characterised in that” described the known combination, while the asymmetric sealing diaphragm and the differential diaphragm surface area appeared after those words.
The Single Judge, relying on the earlier decision in Guala Closures SPA v. AGI Greenpac Ltd. (2024 SCC OnLine Del 3510), treated the portion after “characterised in that” as containing the core inventive features, regarded the remaining features as immaterial to infringement, and granted an interim injunction. The Division Bench stayed that injunction and identified errors of principle. It held that Indian patent law does not give any special consideration to any part of a claim in the course of construction. Because neither Section 7(1) nor Section 10(4)(c) requires claims to contain a characterising portion at all, such a clause cannot be treated as a privileged part of the claim. It distinguished Guala Closures as having been influenced by the patentee’s admission about its inventive features and by regulatory frameworks in the United Kingdom and the European Union that have no counterpart in Indian law.
The Division Bench reaffirmed that claims must be construed holistically and in their entirety, citing Bishwanath Prasad and Roche v. Cipla. It also found that the Single Judge had failed to consider a material limitation in the pre-characterising portion of the claim, namely that the inlet flow path must be longer than the outlet flow path. In the defendant’s valves, the two paths were equal, which the Division Bench regarded as a sufficient distinction at the prima facie stage. The lesson for litigants is that no feature of a granted claim can be set aside as a mere preamble or background element. Every limitation in the claim must be accounted for in the infringement comparison.
Transitional Terms: “Comprising” and Open-Ended Claims
The choice of transitional word in a claim has real consequences. In Frimline Private Limited v. K-Smatco Lifesciences Private Limited, the Delhi High Court examined a pharmaceutical claim drafted with the word “comprising”. Relying on Roche v. Cipla and on standard patent law principles, the Court held that “comprising” signals an open-ended claim: it is enabling in nature and does not confine the claim to the elements specifically named. The Court read the claim together with the specification, citing Bishwanath Prasad, and concluded that a particular compound was covered by the suit patent even though it was absent from a dependent claim. Mapping the constituents of the respondent’s product against Claim 1, the Court found a prima facie case of infringement.
The decision illustrates two points that practitioners should keep in mind. A claim that “comprises” certain elements is not defeated by the addition of further elements in the accused product. And dependent claims do not necessarily cap the scope of the independent claim from which they depend.
Pith and Marrow, Equivalents and the Essential Element Question
Indian courts have long used the phrase “pith and marrow” to describe the substance of an invention, and the doctrine of equivalents has developed alongside it. In SNPC Machines Pvt. Ltd. v. Vishal Choudhary, I.A. 11490/2023 in CS(COMM) 431/2023, decided by the Delhi High Court on 5 March 2024, the Court held that the “all elements rule”, under which every element of the claim must be present in the accused product, cannot be applied to the exclusion of the pith and marrow rule. The Court observed that an infringer should not escape merely by pointing to the absence of some elements of the plaintiff’s product, and applied the function-way-result approach to ask whether a substituted element did substantially the same thing in substantially the same way to achieve substantially the same result. An interim injunction was granted.
The Division Bench reached a similar place in Canva Pty Ltd. v. RxPrism Health Systems, upholding an interim injunction against a software feature. Commentary on the judgment describes the Bench as moving beyond literal differences to ask whether the substantive architectural core of the invention had been taken, applying purposive interpretation and an essential-element approach. The case is also noted for drawing a distinction between product patents and process patents in this analysis.
The Limits of Equivalence: Crystal Crop v. Safex
The expansive reading of claims has limits, and the Delhi High Court marked them in Crystal Crop Protection Ltd. v. Safex Chemicals India Ltd., CS(COMM) 196/2024, 2025:DHC:3382, decided on 7 May 2025 by Justice Amit Bansal. Crystal Crop held Indian Patent No. 417213 for a weedicidal formulation. The claims required a dyeing agent, and the defendant’s product, sold as “Racer”, contained none. Crystal Crop argued that the dye served only an auxiliary purpose and that the doctrine of equivalents applied because the pith and marrow of the invention had been copied.
The Court refused an interim injunction. It held that this was not a case of literal infringement, so the analysis had to proceed on equivalence, and that the dyeing agent was an essential element of the claim tied to a specific technical function, namely identifying treated areas. Applying the Actavis framework, it found that the omission could not be treated as an insubstantial variation. The Court also relied on the prosecution history. The dyeing agent had originally appeared in dependent claims, had been moved into the independent claim during prosecution, and had been defended by the patentee through pre-grant oppositions and other proceedings. Published commentary describes the Court as implicitly invoking prosecution history estoppel, which prevents a patentee from asserting at the infringement stage a broader scope than it accepted to secure grant. The Court distinguished Sotefin SA v. Indraprastha Cancer Society & Research Centre, 2022 SCC OnLine Del 4299, because in that case the omitted element had independently been found non-essential.
Read together, SNPC Machines and Crystal Crop show that Indian courts will not let an infringer escape through trivial substitutions, but will also not let a patentee disown a limitation it chose, and defended, in order to obtain the patent.
Practical Guidance
For patent drafters, the case law means that every word in a claim may later be treated as a deliberate limitation. Essential features should be placed in the independent claim, while features that are genuinely optional belong in dependent claims. The transitional phrase should be chosen with care, since “comprising” and “consisting of” lead to very different scopes. Because the specification will be read with the claims, it should describe the technical function of each feature and state clearly which features are optional. Statements made during prosecution, including responses to examination reports and oppositions, should be written with the knowledge that they may be used later to limit the claims.
For litigants, a claim-by-claim construction should be prepared early, ideally in the form of the claim-construction brief the Delhi High Court Rules now encourage. A plaintiff should prepare for the argument that omitted features were essential and review the prosecution history before suit. A defendant should map the product against every limitation of the claim, including those in the preamble, and examine the file history for narrowing amendments and statements. Parties relying on foreign claim-construction conventions should be ready to explain why they apply under the Indian statute, in light of Automat.
For companies assessing freedom to operate or conducting patent due diligence, the point is that the scope of a patent cannot be judged from the abstract or the title. It depends on construed claims, the specification and the prosecution record, and the same patent can be read broadly in a plaintiff’s hands and narrowly in a defendant’s.
Conclusion
Claim construction in India rests on a few stable principles. Claims define the monopoly under Section 10(4)(c). They are read together with the specification, as Bishwanath Prasad established. They are given a purposive construction through the eyes of a person skilled in the art, following Roche v. Cipla, and they are construed as a whole, as Automat confirmed in 2026. Around those principles, the law of equivalents continues to develop. SNPC Machines and Canva show courts willing to look to the substance of the invention, while Crystal Crop shows them holding patentees to the limitations they chose and defended. The most important open question is how fully Indian courts will adopt the separation of normal interpretation from equivalence introduced by Actavis in the United Kingdom. Until a judgment squarely settles that question, patentees and accused infringers alike should expect construction arguments to be fought out claim by claim, and should prepare their specifications, prosecution records and litigation briefs accordingly.
References
- The Patents Act, 1970 (Sections 7, 10, 48, 59) – https://ipindia.gov.in
- Bishwanath Prasad Radhey Shyam v. Hindustan Metal Industries, (1979) 2 SCC 511 (as discussed in WIPO Patent Judicial Guide, India, para 6.5.1) – https://www.wipo.int/patent-judicial-guide/en/full-guide/india/6.5.1
- F. Hoffmann-La Roche Ltd. v. Cipla Ltd., 225 (2015) DLT 391 (DB), Delhi High Court – https://www.casemine.com/commentary/in/delhi-high-court-in-roche-v-cipla:-affirming-scope-of-basic-chemical-compound-patent-and-interpretation-of-section-3(d)/view
- Automat Industries Pvt. Ltd. v. Aquestia Limited, FAO(OS)(COMM) 123/2025, Delhi High Court Division Bench, 5 January 2026 – https://www.mondaq.com/india/patent/1741200/limits-of-claim-construction-preamble-vs-characterising-clauses-in-indian-patent-disputes
- Frimline Private Limited v. K-Smatco Lifesciences Private Limited, Delhi High Court – https://www.mondaq.com/india/patent/1749868/one-word-big-impact-how-comprising-shapes-patent-protection-in-india
- Canva Pty Ltd. v. RxPrism Health Systems, FAO(OS)(COMM) 211/2023, Delhi High Court Division Bench – https://knallp.com/?p=11878
- SNPC Machines Pvt. Ltd. v. Vishal Choudhary, I.A. 11490/2023 in CS(COMM) 431/2023, Delhi High Court, 5 March 2024 – https://www.bananaip.com/intellepedia/?p=101097
- Crystal Crop Protection Ltd. v. Safex Chemicals India Ltd., CS(COMM) 196/2024, 2025:DHC:3382, Delhi High Court, 7 May 2025 – https://patentlawyermagazine.com/crystal-crop-v-safex-delhi-high-court-on-doctrine-of-equivalents-and-prosecution-history-estoppel-in-patent-disputes/
- High Court of Delhi Rules Governing Patent Suits, 2022 – https://www.wipo.int/wipolex/en/legislation/details/21495
- Catnic Components Ltd. v. Hill & Smith Ltd. [1982] RPC 183; Improver Corp. v. Remington Consumer Products Ltd. [1990] FSR 181; Kirin-Amgen Inc. v. Hoechst Marion Roussel Ltd. [2005] RPC 9; Actavis UK Ltd. v. EliLilly and Co. [2017] UKSC 48 (as discussed in WIPO Patent Judicial Guide, India, para 6.5.1) – https://www.wipo.int/patent-judicial-guide/en/full-guide/india/6.5.1