Patent infringement litigation in India, as in every major patent jurisdiction, is rarely a simple contest between an unimpeachable patent and an undeniable act of infringement. The defendant in a patent infringement suit has available to it a range of defences statutory, equitable and procedural that can defeat or substantially limit the plaintiff’s claim even where the technical act of infringement is not in dispute. These defences reflect the law’s recognition that patent rights, however valuable and however legitimate, are not absolute that they are bounded by conditions of validity, by principles of fair commercial conduct, by public interest considerations and by rules of procedure that prevent their misuse as instruments of harassment or unjust enrichment. Section 107 of the Patents Act, 1970 is the principal statutory provision governing defences to infringement, but the full landscape of available defences extends significantly beyond it, drawing on other provisions of the Patents Act, on the equitable doctrines developed by Indian courts and on the broader principles of civil procedure that govern the conduct of infringement proceedings. A complete understanding of defences to patent infringement in India requires engagement with this entire landscape not merely with the text of Section 107 but with the case law, the procedural framework and the strategic considerations that determine which defences are available, how they are pleaded and what consequences follow from their success.
The importance of a thorough understanding of infringement defences is not confined to defendants. Patent holders who understand the defences available to their opponents are better positioned to assess the strength of their infringement claims before commencing litigation, to anticipate the arguments they will face and to structure their litigation strategy accordingly. For practitioners on both sides of patent disputes, the defences to infringement are as important a body of knowledge as the law of infringement itself they define the outer boundary of the patent holder’s monopoly and the inner boundary of the defendant’s freedom to operate.
Section 107 – The Statutory Gateway
Section 107 of the Patents Act, 1970 provides the primary statutory framework for defences to patent infringement. Section 107(1) provides that in any suit for infringement of a patent, every ground on which it might be revoked under Section 64 shall be available as a ground of defence. This provision establishes a fundamental principle of Indian patent law: that the validity of a patent is always open to challenge in infringement proceedings and that a defendant who can establish any ground on which the patent could be revoked has a complete defence to the infringement claim.
The significance of Section 107(1) cannot be overstated. It means that a defendant in an infringement suit is not required to bring a separate revocation petition it can raise validity challenges directly in the infringement proceedings as a defence and as a counter-claim under Section 64. The grounds available under Section 64 are comprehensive, encompassing lack of novelty, lack of inventive step, non-patentable subject matter under Section 3, insufficiency of description, failure to disclose information under Section 8, fraud and a range of other deficiencies that may afflict a granted patent. Each of these grounds is available to the defendant in an infringement suit by virtue of Section 107(1) and the defendant who successfully establishes any one of them will both defeat the infringement claim and secure the revocation of the patent or at minimum, the revocation of the specific claims in issue.
Section 107(2) provides that the defendant in an infringement suit may, in addition to any other ground of defence open to him, also plead that the patentee has committed acts of fraud in obtaining the patent, has obtained the patent in contravention of a secrecy direction or has used the patent to impose conditions in a contract that are contrary to Section 140 of the Act the provision that renders certain restrictive licensing conditions void. Section 107(2) thus adds further specific defences to those derived from Section 64, reflecting the legislature’s intention to provide defendants with a comprehensive toolkit for challenging both the validity and the conduct of the patent holder.
Invalidity as a Defence – The Section 64 Grounds
The most significant and most frequently pleaded defences under Section 107(1) are those based on the invalidity of the patent the grounds that, if established, would support revocation under Section 64. Among these, lack of novelty and lack of inventive step are by far the most commonly invoked, reflecting the fact that prior art searches by defendants frequently uncover documents that were not identified or adequately considered during examination.
Lack of novelty as a defence requires the defendant to identify prior art a document, a prior use or a prior disclosure that anticipates the claims in suit. The anticipation must be complete: every element of the claim must be disclosed by the single prior art document or prior use, since combination of multiple documents is the domain of obviousness rather than novelty. The prior art must also pre-date the priority date of the relevant claim not the filing date or grant date, but the priority date from which the patent’s right to exclude is measured. In practice, the identification and presentation of prior art evidence in infringement proceedings is a highly technical exercise that requires both technical expertise in the relevant field and legal precision in mapping the prior art disclosure against the claim elements.
Lack of inventive step or obviousness as a defence is, in many cases, the more powerful and more commonly established invalidity ground. It does not require that a single document discloses every element of the claim it requires only that the claimed invention would have been obvious to a person skilled in the art at the priority date in light of the prior art taken as a whole, including the common general knowledge of the skilled person. The Delhi High Court’s engagement with the obviousness standard in a series of pharmaceutical and technology patent cases has produced a developing body of jurisprudence on what constitutes the relevant skilled person, what constitutes common general knowledge and how the combination of prior art documents and common general knowledge is assessed in determining obviousness.
Non-patentable subject matter under Section 3 is the third major category of invalidity defence and it is of particular importance in pharmaceutical patent litigation where Section 3(d) is invoked. A defendant who can establish that the patented compound is a new form of a known substance within the meaning of Section 3(d) and that it does not demonstrate significantly enhanced efficacy, has a complete invalidity defence that will defeat the infringement claim entirely. The centrality of Section 3(d) to Indian pharmaceutical patent litigation demonstrated by the Novartis judgment and by a large body of Patent Office and IPAB decisions means that this defence is available and potentially powerful in a wide range of pharmaceutical infringement cases.
Insufficiency of description is an invalidity defence that has grown in importance as Indian patent litigation has matured. A patent whose specification does not enable a person skilled in the art to reproduce the invention across the full scope of the claims is invalid for insufficiency and the defendant who establishes insufficiency defeats the infringement claim. In biotechnology and pharmaceutical cases particularly, where patentees frequently seek broad functional claims supported by a narrow set of working examples, the insufficiency defence has proved a potent weapon for defendants challenging over-broad claims.
The Bolar Exemption – Section 107A(a)
As discussed in the context of parallel imports and government use, Section 107A(a) of the Patents Act provides a specific statutory defence to infringement for acts undertaken solely for the purpose of developing and submitting information required for regulatory approval. The Bolar exemption is a complete defence to infringement for qualifying acts it is not merely a discretionary consideration but a statutory entitlement that the defendant can assert as of right.
The practical significance of the Bolar exemption as a defence in infringement proceedings arises most commonly in the pharmaceutical context, where a generic manufacturer is sued for infringement based on activities synthesis, formulation, bioequivalence testing conducted in preparation for a regulatory application. The defendant’s ability to establish that these activities fall within Section 107A(a) depends on demonstrating that they were solely for the purpose of generating data for regulatory submission and that no commercial activity occurred under the cover of the exemption. The evidential requirements for establishing the Bolar exemption documentary records of the regulatory development programme, evidence that no commercial manufacture or sale occurred and expert evidence on the standard practices of generic pharmaceutical development are an important aspect of litigation preparation for defendants relying on this defence.
The Experimental Use Defence
Section 47(3) of the Patents Act provides that a patent does not prevent the making or using of a patented product or process solely for experimental purposes relating to the subject matter of the patent. This experimental use defence is conceptually distinct from the Bolar exemption it covers a broader range of experimental activities that are not confined to regulatory development purposes but it is narrower in the sense that it requires the use to be solely for experimental purposes relating to the subject matter of the patent and it does not cover commercial exploitation of experimental results.
The experimental use defence in Indian patent law has not been extensively developed through judicial decisions and its precise scope remains somewhat uncertain. The requirement that the experiment relate to the subject matter of the patent rather than to some unrelated purpose that happens to involve the patented invention is a limitation that has been interpreted broadly in some jurisdictions and narrowly in others. In India, the courts have had limited occasion to examine the defence in detail and the parameters of what constitutes experimental use relating to the subject matter of the patent remain to be fully defined.
Prior Use as a Defence
The prior use defence sometimes called the right of prior user is recognised in Indian patent law as an equitable principle that protects a person who was using an invention before the patent’s priority date. Section 64(1)(b) of the Patents Act enables revocation on the ground of prior secret use in India before the priority date and the prior user’s right to continue that use is protected as a matter of equity even after the grant of a patent. The rationale for this protection is straightforward: a person who independently developed and used an invention before the patent was filed should not be deprived of the ability to continue that use merely because a later applicant obtained a patent over the same invention.
The prior use defence requires the defendant to establish that it was using the invention or had made serious and effective preparations to use it before the priority date of the patent in suit and that the use was continuous and genuine rather than token or pretextual. The defence does not extend to cover any expansion of the use beyond the scope established before the priority date and it cannot be assigned or transferred separately from the business in which the prior use occurred. A prior user who has assigned the relevant business to another entity can only transfer the prior use right as part of that business it cannot be separately extracted and assigned.
In Enercon (India) Ltd. v. Aloys Wobben, the Delhi High Court engaged with the prior use defence in the context of wind turbine technology patents, examining the evidence of prior use and the scope of the right to continue that use under Indian patent law. The case illustrates both the potential power of the prior use defence and the rigorous evidentiary standard that courts apply in assessing it the defendant must produce credible contemporaneous evidence of prior use and assertions of prior use without supporting documentation will not be accepted.
Exhaustion of Rights – Section 107A(b)
The doctrine of exhaustion of patent rights as expressed in Section 107A(b) is a defence available to any person who imports a patented product from a person duly authorised to sell or distribute it. Where the patented product has been placed on the market in another country by or with the consent of the patent holder and the defendant imports that product into India, Section 107A(b) provides a complete defence to the infringement claim. The exhaustion defence is discussed in detail in the article on parallel imports its availability as a defence in infringement proceedings is its most practical manifestation.
The Licence Defence
The most straightforward defence to a patent infringement claim is that the defendant has a valid licence to use the patented invention either a voluntary licence granted by the patentee, a compulsory licence granted by the Controller or a government use authorisation under Section 99. A defendant who can produce a valid licence that covers the acts complained of as infringement has a complete defence, since licensed use is by definition not infringing use.
The licence defence requires careful attention to the terms of the licence its scope, its duration, its territorial extent and any conditions attached to it. A defendant who has exceeded the scope of its licence by using the patented invention in a field of use not covered by the licence, in a territory not covered or after the licence has expired cannot rely on the licence as a defence to the extent of the excess. Licence scope disputes are therefore a significant source of litigation in their own right and the determination of what a licence covers particularly where the licence agreement is ambiguous or where the infringing act is alleged to fall outside the licence’s scope by a fine margin can be as contested as the underlying infringement question.
Acquiescence, Delay and Estoppel
Indian patent law, like other systems of equity-informed jurisprudence, recognises that a patentee who has stood by and allowed an infringer to continue its activities without complaint particularly where the infringer has invested substantially in reliance on the patentee’s inaction may be precluded from obtaining relief or at least from obtaining the full extent of the relief to which it would otherwise be entitled. The doctrines of acquiescence, delay and estoppel operate as equitable defences that do not defeat the underlying infringement claim but may restrict the remedies available to the patentee, particularly the grant of a permanent injunction.
In Hindustan Lever Ltd. v. Godrej Soaps Ltd., the Bombay High Court examined the doctrine of acquiescence in a patent context and held that where a patentee had knowledge of an infringement and delayed in bringing proceedings for an unreasonable period, the court would consider this delay in the exercise of its discretion to grant equitable relief. The principle is not that delay bars the claim entirely the Limitation Act, 1963 provides the relevant limitation periods for patent infringement claims, which are three years from the date of infringement but that delay may affect the nature and extent of the court’s equitable discretion in fashioning relief.
Estoppel as a defence arises where the patentee has made a representation by conduct, by words or by silence upon which the defendant has relied to its detriment and where it would be inequitable to allow the patentee to assert the infringement claim inconsistently with that representation. Estoppel by conduct is the most commonly encountered form in patent litigation and it typically arises where the patentee has given some indication through correspondence, through a prior licence negotiation or through its public statements that it would not enforce the patent against the defendant’s particular activities.
Prosecution History Estoppel
Prosecution history estoppel the principle that claim amendments and arguments made during prosecution to overcome prior art or examination objections may limit the scope of the claims in infringement proceedings is a defence that has been recognised by Indian courts as a relevant consideration in claim construction, though its precise contours have not been as extensively developed in Indian jurisprudence as in United States patent law.
The principle operates as follows: where a patentee has, during prosecution, narrowed a claim by amendment or by argument to distinguish it from the prior art, the patentee cannot subsequently assert in infringement proceedings that the claim covers subject matter that was surrendered during prosecution. The prosecution history creates a record of the boundaries of the patent’s claims as those boundaries were defined by the patentee itself and a defendant who can demonstrate that its activities fall within the surrendered subject matter has a defence to the infringement claim.
In Farbewerke Hoechst v. Unichem Laboratories, the Bombay High Court considered the relevance of prosecution history in claim construction and held that the history of the patent’s prosecution before the Patent Office was a relevant consideration in interpreting the scope of the claims and that the patentee could not assert a scope for the claims that was broader than the scope that had been established during prosecution. This decision laid the groundwork for the recognition of prosecution history estoppel as an infringement defence in India, though subsequent courts have engaged with the doctrine to varying degrees of depth and consistency.
Non-Obviousness of the Infringing Product – The Gillette Defence
The Gillette defence named after the English case of Gillette Safety Razor Co. v. Anglo-American Trading Co. Ltd. (1913) 30 RPC 465 is a defence to infringement that operates by reference to the prior art rather than by direct challenge to the validity of the patent. It proceeds on the following logic: if the defendant’s product or process was known or obvious in light of the prior art at the priority date, then either the patent claims do not cover it because if they did, the patent would be invalid for lack of novelty or inventive step or if the claims do cover it, the patent is invalid. Either way, the defendant does not infringe a valid patent.
The Gillette defence has been recognised in Indian patent litigation as a useful practical tool for defendants, particularly in cases where the defendant wishes to avoid the full cost and complexity of a formal invalidity challenge while still protecting its freedom to operate. The Delhi High Court has applied the defence in several cases, recognising its logical validity as a shortcut to the conclusion that either non-infringement or invalidity must follow from the prior art position. In Bajaj Auto Ltd. v. TVS Motor Company Ltd., the Madras High Court engaged with aspects of the Gillette logic in examining the relationship between the prior art, the scope of the patent claims and the defendant’s product, though the case is better known for its important pronouncements on the grant of interim injunctions in patent matters.
Misuse and Abuse of Patent Rights
Patent misuse the use of a patent right in a manner that extends the patent monopoly beyond its legitimate scope or that imposes anti-competitive conditions is recognised in Indian law through Section 140 of the Patents Act and through the Competition Act, 2002. Section 140 renders void certain conditions in patent licences that seek to extend the patent’s reach beyond its legitimate scope such as conditions requiring the licensee to acquire unrelated goods from the licensor or conditions restricting the licensee from challenging the patent’s validity. A defendant who can demonstrate that the plaintiff has engaged in conduct contrary to Section 140 or that constitutes an abuse of dominance under the Competition Act has a defence that can defeat or restrict the relief available to the plaintiff.
The Competition Commission of India’s jurisdiction over the licensing conduct of SEP holders established by the Delhi High Court in the Ericsson proceedings means that a defendant in a patent infringement suit who has complained to the CCI about the plaintiff’s licensing conduct may be able to use the pendency of the CCI proceedings or the CCI’s findings, as a basis for resisting the grant of injunctive relief in the infringement suit. The intersection of patent enforcement and competition law creates a complex procedural and substantive landscape that defendants in SEP-related infringement proceedings must navigate with care.
Quia Timet Actions and Groundless Threats
Section 109 of the Patents Act provides a specific remedy for a person who has been threatened with patent infringement proceedings without justification a remedy that can itself be used as an offensive weapon by a defendant who has received groundless threats from a patent holder. Where a person has been threatened with infringement proceedings and the threat is groundless because the patent is invalid, because the defendant’s activities do not infringe or because the patent holder has no genuine intention to bring proceedings the threatened person may bring a quia timet action for a declaration of non-infringement and an injunction against the continuation of the threats.
The groundless threats provision is an important counterbalance to the in terrorem effect of patent infringement threats, which can damage the commercial relationships and market position of the threatened party even where the threat has no legal foundation. A patent holder who makes sweeping infringement threats without adequate prior art analysis and claim mapping risks a groundless threats action that can result in a declaration of non-infringement, an injunction and an award of damages consequences that make careful legal analysis before making infringement allegations a matter of commercial prudence as well as professional obligation.
Conclusion
The defences to patent infringement available under Indian law from the statutory invalidity grounds of Section 107(1), through the Bolar exemption and experimental use defence, to the equitable doctrines of acquiescence, estoppel and prosecution history estoppel and the logical elegance of the Gillette defence constitute a comprehensive and sophisticated body of law that reflects the patent system’s recognition that exclusivity must be earned, maintained and exercised within defined boundaries. Section 107 is the gateway through which the most powerful of these defences the invalidity grounds are channelled into infringement proceedings, but the full landscape of available defences extends far beyond it, drawing on every corner of the Patents Act and on the principles of equity and competition law that surround it.
For defendants in patent infringement proceedings, the availability and strength of these defences is often the most commercially significant question in the litigation more so, in many cases, than the technical question of whether infringement has occurred. A defendant who can establish invalidity does not merely defeat the infringement claim but destroys the patent entirely, restoring the invalidly patented subject matter to the public domain. A defendant who can establish the Bolar exemption, prior use or exhaustion defeats the specific claim without affecting the patent’s broader validity. And a defendant who can establish acquiescence, estoppel or prosecution history estoppel may limit the relief available without defeating the claim on its merits. The strategic selection and presentation of the most appropriate defences individually and in combination is the art of patent infringement defence and it is an art that requires the deepest familiarity with the full body of law that this article has surveyed.
References
- The Patents Act, 1970 https://ipindia.gov.in
- The Patents Rules, 2003 https://ipindia.gov.in
- Novartis AG v. Union of India, (2013) 6 SCC 1 https://main.sci.gov.in
- Bajaj Auto Ltd. v. TVS Motor Company Ltd., Madras High Court https://hcmadras.tn.nic.in
- Enercon (India) Ltd. v. Aloys Wobben, Delhi High Court https://delhihighcourt.nic.in
- F. Hoffmann-La Roche Ltd. v. Cipla Ltd., (2012) 49 PTC 356 (Del) https://delhihighcourt.nic.in
- Telefonaktiebolaget LM Ericsson v. Competition Commission of India, W.P.(C) 464/2014 https://delhihighcourt.nic.in
- Competition Act, 2002 https://cci.gov.in
- Manual of Patent Office Practice and Procedure https://ipindia.gov.in
- TRIPS Agreement, WTO https://www.wto.org/english/docs_e/legal_e/27-trips.pdf
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