Supreme Court Issues Notice On Plea Against Delhi HC Ruling That Patent Revocation Plea Survives Expiry

The Supreme Court on Monday issued notice on a plea challenging a Delhi High Court ruling that a patent revocation petition remains maintainable and survives even after expiry of the patent and is not barred merely because an invalidity defence is raised in a parallel infringement suit.

A Bench of Justices P.S. Narasimha and Alok Aradhe issued notice on the special leave petition filed by by Boehringer Ingelheim Pharma GmbH and listed the matter for final disposal on May 25, 2026

The case concerns a patent granted to Boehringer Ingelheim for the diabetes drug Linagliptin, with a priority date of August 21, 2002. The patent was granted on October 5, 2022 and expired on August 18, 2023 by efflux of time.

Macleods Pharmaceuticals Ltd filed a revocation petition under Section 64 of the Patents Act before the Delhi High Court seeking revocation of the patent. Around the same time, Boehringer instituted an infringement suit before the High Court of Himachal Pradesh alleging infringement of the same patent, in which Macleods raised invalidity as a defence under Section 107 of the Act.

During the pendency of these proceedings, Boehringer moved applications before the Delhi High Court seeking dismissal of the revocation petition. It contended that the petition could not continue once an invalidity defence had been raised in the infringement suit and further argued that the expiry of the patent rendered the revocation proceedings infructuous.

The Delhi High Court rejected these submissions. Framing two pure questions of law, it held that a revocation petition under Section 64 can be maintained and can survive even after an invalidity defence is raised in a suit and that such a petition would also continue despite expiry of the patent.

On the issue of expiry, the High Court held that the patent's lapse does not terminate the underlying cause of action, noting that “the cause of action in the suit continues to survive qua the claim for damages,” and that the revocation petition would likewise survive.

On the interplay between remedies, the High Court held that revocation proceedings and invalidity defenses operate in distinct legal spheres. It observed that revocation results in the patent being effaced from the register with effect in rem, whereas an invalidity defence in an infringement suit operates only inter partes and does not by itself remove the patent from the register.

Aggrieved by these findings, Boehringer has approached the Supreme Court, which has issued notice on the plea.