REVOCATION BEYOND EXPIRY: THE DELHI HIGH COURT ON THE STRUCTURAL INDEPENDENCE OF SECTION 64

The Delhi High Court’s Division Bench in Boehringer Ingelheim Pharma GmbH & Co. KG v. Controller of Patents has delivered a significant ruling on the architecture of revocation under the Patents Act, 1970, in the context of IN 243301 covering Linagliptin. The decision addresses how Section 64 revocation interacts with Section 107 invalidity defences and with the expiry of the patent itself.

The Court framed two central questions.

1.       Can a revocation petition under Section 64 be instituted or continue even after the petitioner has raised invalidity as a defence under Section 107 in an infringement suit.

2.       Does a revocation petition survive once the patent has expired by efflux of time.

On both issues, the Court answered in the affirmative and drew a clear structural distinction between the two provisions. A petition under Section 64 is an independent, in rem mechanism that can cancel the patent and efface it from the register, whereas an invalidity plea under Section 107 is confined to the infringement suit and has only inter partes effect. Raising invalidity as a defence therefore does not bar, exhaust, or render infructuous a standalone revocation action.

The Court further held that expiry of the patent does not make a pending revocation petition meaningless. A patent continues to be a “patent granted” in law even after expiry, and revocation, if granted, operates retrospectively and in rem so that the patent is rendered ineffective and incapable of assertion from the date of grant, not merely from the date of the revocation order. This retrospective effect directly bears on damages and accounts for past infringement, and explains why a party can retain a real and live interest in pursuing revocation even after the term has run out.

In conceptual terms, the ruling reinforces that Sections 64 and 107 occupy distinct normative spaces within the Act and that expiry is no sanctuary for a patent whose very grant is under challenge. It clarifies that revocation is a retrospective, in rem remedy directed at the legitimacy of the original grant, whereas invalidity in defence is a case-specific response within an infringement suit, leaving the broader legal status of the patent untouched.

Boehringer Ingelheim Pharma GMBH and Co. KG v. The Controller of Patents & Anr. [LPA 129/2025, CM APPL. 10551/2025]

Copy of the judgment can be accessed at: