Summary

The Delhi High Court Division Bench held that patent revocation petitions under Section 64 of the Patents Act remain maintainable even after patent expiry, and that filing a Section 107 invalidity defence in an infringement suit does not preclude a separate revocation petition.

The Court emphasized that revocation operates retrospectively and in rem (affecting all parties), while Section 107 defence operates only in personam (between specific parties) — making them fundamentally distinct remedies.

Factual Background

In February 2022, Macleods Pharmaceuticals filed a revocation petition seeking to invalidate Boehringer Ingelheim's Indian Patent IN'243301 covering Linagliptin (a diabetes medication). Two days later, Boehringer initiated infringement proceedings before the Himachal Pradesh High Court. Macleods raised a Section 107 invalidity defence in the HP suit. On August 18, 2023, Patent IN'243301 expired by efflux of time. Boehringer then applied to dismiss the revocation petition.

Two Legal Issues Decided

Issue 1: Can a revocation petition survive after patent expiry? Yes. Patent expiry renders the patent unenforceable prospectively but does not erase its legal existence. Section 2(m) defines "patent" broadly without restricting it to in-force patents. Where a damages claim for past infringement remains pending, Macleods retains a real legal interest in establishing invalidity ab initio.

Issue 2: Does a Section 107 defence bar a Section 64 petition? No. Section 64 revocation operates in rem — removes the patent from the Register with retrospective effect, benefits the entire public. Section 107 defence operates in personam — results only in dismissal of that specific suit, patent remains on the Register. Section 151 of the Patents Act itself recognizes this distinction.

Correct Reading of Aloys Wobben

The Court clarified that Aloys Wobben v. Yogesh Mehra [(2014) 15 SCC 360] only prohibits pursuing both a standalone Section 64 petition and a Section 64 counter-claim simultaneously — it does not address or restrict a Section 107 defence alongside a Section 64 petition.

Decision & Significance

Boehringer's appeal dismissed. Macleods' revocation petition to proceed. This judgment confirms that patent challengers retain revocation rights even post-expiry (where damages claims are pending), strongly affirms that revocation operates ab initio, and preserves the ability to pursue Section 107 and Section 64 remedies simultaneously.