Summary
In the case of Boehringer Ingelheim Pharma GmbH & Co. KG v. Controller of Patents & Anr., the Delhi High Court held that a revocation petition under Section 64 of the Patents Act can continue even after the patent has expired. The court also ruled that raising an invalidity defence under Section 107 in an infringement suit does not bar or extinguish the statutory right to pursue revocation. The judgment clarifies that revocation operates retrospectively and in rem, and that expiry of a patent does not defeat pending revocation proceedings.
Background
Boehringer Ingelheim Pharma GmbH (Boehringer) was granted an Indian Patent bearing registration number IN 243301 for the pharmaceutical product Linagliptin on 5 October 2022, with a priority date of 21 August 2002. On 17 February 2022, Macleods Pharmaceuticals Limited (Macleods) filed a revocation petition under Section 64(1) of the Patents Act before the Delhi High Court seeking revocation of the patent.
Two days later, Boehringer instituted an infringement suit before the High Court of Himachal Pradesh (HP High Court) alleging that Macleods had infringed IN 243301 and seeking injunction and other consequential reliefs including damages and account of profits. In its written statement in the suit, Macleods raised invalidity of the patent as a defence under Section 107(1) of the Act.
An ad interim injunction was granted by the HP High Court in favour of Boehringer on 25 February 2022 and later confirmed on 21 April 2022. The appeal filed by Macleods against the injunction was dismissed on 12 March 2024.
During the pendency of these proceedings, the patent expired on 18 August 2023 by efflux of time.
Boehringer thereafter filed applications before the Delhi High Court seeking dismissal of the revocation petition on two grounds. First, that once invalidity had been pleaded as a defence under Section 107 in the infringement suit, the revocation petition could not continue. Second, that after the expiry of the patent, no revocation proceedings could survive.
These applications were dismissed by the learned Single Judge, which led to the present appeal.
Questions before the Court
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- Whether a revocation petition under Section 64 can be instituted or can survive after the petitioner has pleaded invalidity as a defence under Section 107(1) in an infringement suit filed by the patentee.
- Whether a revocation petition can be instituted or can continue after the patent whose revocation is sought has expired.
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Arguments Presented by the Parties
Issue 1: Revocation petition after a Section 107 defence
Boehringer’s submissions
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- Boehringer argued that once Macleods raised invalidity under Section 107 in the infringement suit, Macleods should not be allowed to continue a separate revocation petition, as it could lead to parallel proceedings and possibly conflicting outcomes in different High Courts.
- Boehringer relied on the Supreme Court decision in Aloys Wobben v. Yogesh Mehra to contend that after an infringement suit, the defendant must proceed through the suit route and not by a separate revocation petition.
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Macleods’ arguments
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- Macleods argued that a Section 107 defence and a Section 64 revocation petition are not the same in scope and consequence. Macleods stressed that Section 107 is a defence in a suit, while Section 64 is a direct route to revocation.
- Macleods relied on Section 151, to assert that revocation orders and findings in infringement suits differ in terms of entries made by the Controller. That is, a revocation petition, if it succeeded, would, by operation of Section 151(1), require the order to be transmitted to the Controller, who would make a suitable entry in the Register of Patents, effacing, from the Register, the patent, as if it had never existed.
- On the other hand, an invalidity plea raised under Section 107, if it succeeded, would be required to be transmitted to the Controller of Patents under Section 151(2), who would make a suitable entry in the supplemental record, on the basis of which the defendant in the suit could take separate steps under Section 71(1) of the Patents Act for rectification of the Register. A finding of invalidity, which would follow from a successful Section 107 challenge, would not, therefore, result in effacing of the suit patent from the Register of Patents.
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Issue 2: Revocation petition after patent expiry
Boehringer’s submissions
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- Boehringer argued that revocation assumes that the patent is alive, and there can be no revocation of an expired patent.
- Boehringer also argued that after expiry, Macleods could no longer qualify as a “person interested” for the purposes of Section 64
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Macleods’ arguments
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- Macleods argued that Section 64 is a standalone right and is not limited by patent expiry.
- Macleods also argued that expiry does not end an infringement dispute fully because claims like damages or account of profits may survive, and therefore the revocation challenge also remains meaningful.
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Court’s Analysis
Does a revocation petition survive patent expiry?
The court began by identifying the key expressions in Section 64, namely “patent”, “revoked”, “person interested”, and “or on a counterclaim”. The court stated that the meaning and interaction of these expressions would determine whether a revocation petition can survive the expiry of a patent.
The court first addressed whether revocation under Section 64 operates prospectively or retrospectively. The court observed that Section 64 treats a revocation petition and a counterclaim in an infringement suit as parallel routes to the same consequence, namely, revocation of the patent.
The court reasoned that a counterclaim in an infringement suit necessarily challenges the very grant of the patent in relation to past acts of alleged infringement. If such a counterclaim succeeds, the patent cannot remain valid for the period prior to the suit. Therefore, the court held that revocation must invalidate the grant itself and must date back to the date of grant.
The court further observed that the grounds of revocation under Section 64 are such that, if established, they demonstrate that the patent ought never to have been granted. This also supports the conclusion that revocation nullifies the patent ab initio.
The court relied on comparative reasoning, and referred to the UK Supreme Court decision in Virgin Atlantic Airways Ltd v. Zodiac Seats UK Ltd to support the view that revocation is an act in rem and operates retrospectively.
On the meaning of “patent”, the court stated that the Patents Act defines “patent” as “a patent for any invention granted under this Act”. The court said a granted patent remains a patent even after it expires, though it becomes unenforceable for future restraint.
On “person interested”, the court held that Macleods had a real and live interest because Boehringer had sued it for infringement, and if revocation succeeds it would invalidate the patent from inception and defeat claims including damages. The court therefore treated Macleods as a “person interested” and held that the revocation petition survives patent expiry.
The court concluded that expiry merely takes away the patentee’s right to seek prospective injunction, but does not extinguish claims relating to past infringement. Consequently, the revocation petition also continues to have legal significance.
Is a revocation petition barred after a Section 107 defence?
The court approached this issue by first clarifying the relationship between three distinct mechanisms under the Patents Act:
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- A revocation petition under Section 64
- A counter claim under Section 64 in an infringement suit
- An invalidity defence under Section 107
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The court held that the controversy could not be resolved unless the statutory scheme was properly understood.
The court first examined whether the Supreme Court decision in Aloys Wobben barred continuation of the revocation petition. The court observed that Aloys Wobben only prohibits the simultaneous pursuit of a revocation petition and a counterclaim seeking the same relief under Section 64. It does not hold that a revocation petition becomes barred merely because an invalidity defence under Section 107 is raised in a suit.
The Court then clarified the distinction between revocation under Section 64 and invalidity under Section 107. A Section 107 plea is only a defence in an infringement suit. Even if it succeeds, it results in dismissal of the suit. It does not remove the patent from the register.
In contrast, a successful revocation petition leads to removal of the patent from the register and invalidates the grant itself. The court relied on Section 151 to show that revocation orders are entered in the register, whereas findings in suits are entered only in a supplemental record.
The court therefore held that the two remedies operate in different spheres. Raising a Section 107 defence does not extinguish or restrict the statutory right to pursue revocation under Section 64.
Findings & Conclusion
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- The court held that a revocation petition under Section 64 is maintainable and survives even after expiry of the patent whose revocation is sought.
- The court held that a revocation petition can be instituted even after the alleged infringer has taken an invalidity defence under Section 107 in an infringement suit.
- The court dismissed the appeal and made no order as to costs.
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Case Citation: Boehringer Ingelheim Pharma GmbH & Co. KG v. Controller of Patents & Anr., LPA 129/2025 (Del HC Feb. 24, 2026). Available on https://indiankanoon.org/doc/76672212/
Authored by Gaurav Mishra, Patent Attorney, BananaIP Counsels