Delhi High Court Rules Patent Revocation Proceedings Persist Post-Expiry and Despite Section 107 Defence

In a significant ruling on patent revocation and infringement procedures, the Delhi High Court in Boehringer Ingelheim Pharma GmbH & Co. KG v. Controller of Patents & Anr. held that revocation petitions under Section 64 of the Patents Act survive the expiry of the patent and are not barred by invalidity defences raised under Section 107 in infringement suits.

Boehringer Ingelheim Pharma was granted Indian Patent IN 243301 for the pharmaceutical compound Linagliptin on 5 October 2022, with a priority date of 21 August 2002. Prior to the patent’s expiry, Macleods Pharmaceuticals Limited filed a revocation petition under Section 64(1) on 17 February 2022 before the Delhi High Court, seeking to revoke the patent.

Two days later, Boehringer initiated an infringement suit in the Himachal Pradesh High Court alleging that Macleods infringed the patent and sought injunctive relief, damages, and an account of profits. Macleods responded by raising invalidity as a defence under Section 107(1) of the Patents Act.

The Himachal Pradesh High Court granted an ad interim injunction in favour of Boehringer on 25 February 2022, which was confirmed on 21 April 2022. Macleods’ appeal against the injunction was dismissed on 12 March 2024. Meanwhile, the patent expired on 18 August 2023 by efflux of time.

Following expiry, Boehringer filed applications in the Delhi High Court seeking dismissal of the revocation petition on two grounds: first, that the invalidity defence under Section 107 in the infringement suit barred continuation of the separate revocation petition; and second, that revocation proceedings cannot survive after patent expiry.

The court examined whether a revocation petition under Section 64 can survive after a defendant pleads invalidity under Section 107 in an infringement suit and whether revocation proceedings can continue post-patent expiry.

Boehringer contended that allowing both a Section 107 defence and a Section 64 revocation petition would lead to parallel proceedings and conflicting outcomes in different courts. It relied on the Supreme Court’s decision in Aloys Wobben v. Yogesh Mehra, arguing that once invalidity is raised in an infringement suit, the defendant must proceed solely through that suit rather than a separate revocation petition.

Conversely, Macleods argued that the scope and consequences of a Section 107 defence and a Section 64 revocation petition differ fundamentally. Section 107 is a defence within an infringement suit, while Section 64 provides a direct statutory route to revoke a patent.

Macleods emphasized that under Section 151, the Controller of Patents makes different entries depending on the proceeding. A successful revocation petition under Section 64 requires the Controller to erase the patent from the Register of Patents, effectively treating it as if it never existed. In contrast, a successful invalidity defence under Section 107 results in a supplemental record entry, which does not efface the patent but allows for rectification steps under Section 71.

The Delhi High Court’s ruling affirms that revocation petitions under Section 64 operate retrospectively and in rem, meaning they affect the patent’s status as a whole and not just between parties. Consequently, the expiry of a patent does not extinguish pending revocation proceedings.

This judgment clarifies procedural and substantive issues surrounding patent revocation and infringement defences, ensuring that statutory revocation rights remain enforceable even after patent expiry and despite parallel infringement litigation.