Patent Revocation Petition Survives Even If Patent Expires By Efflux Of Time: Delhi High Court

Holding that revocation operates retrospectively and in rem, the Delhi High Court has ruled that expiry of a patent does not render a pending revocation petition infructuous.

A Division Bench of Justice C. Hari Shankar and Justice Om Prakash Shukla on Tuesday held “a revocation petition would be maintainable, and would continue to survive, even after the patent of which revocation is sought expires by efflux of time"

The court further clarified that once revoked, the patent is “rendered ineffective and incapable of assertion ab initio.”

The ruling came in an appeal filed by Boehringer Ingelheim Pharma GmbH & Co. KG against a single judge's order permitting a revocation petition filed by Macleods Pharmaceuticals Limited to proceed.

Boehringer had argued that its patent for the drug Linagliptin had expired in August 2023 and that the revocation petition was therefore “akin to flogging a dead horse.” It also contended that since Macleods had raised an invalidity defence under Section 107 of the Patents Act in a separate infringement suit, it was barred from maintaining an independent revocation petition under Section 64.

Rejecting the first contention, the Bench held, “A patent, once granted, therefore, remains a 'patent' under the Patents Act, and does not cease to remain a patent which was granted, even if it expires by efflux of time. The expiry of the life of the patent merely renders it unenforceable, and does not denude it of its character as a 'patent granted under' the Patents Act.”

The Division Bench also emphasised that Section 107 and Section 64 operate in distinct legal spheres. A Section 107 plea merely enables a defendant to resist an infringement claim by questioning validity in that suit. By contrast, a Section 64 petition seeks revocation of the patent itself, which, if allowed, renders the grant void from inception and unenforceable against the world.

Interpreting the Supreme Court's decision in Aloys Wobben v. Yogesh Mehra, the Bench held that the statutory bar applies only where a counter-claim for revocation has been filed in the infringement suit. It stated, “A revocation petition can be instituted even after a Section 107 invalidity defence is taken in the infringement suit.”

The Court also underscored that the grounds under Section 64 necessarily strike at the root of the grant, observing that if a patent is found invalid on those grounds, “it would mean that the very grant of the patent was invalid.”

Holding that Macleods continued to have a “real and live interest” in challenging the patent's validity in view of the damages claim in the infringement suit, the Division Bench dismissed Boehringer's appeal.