Patent Revocation Under Section 64: The High Court Route to Knocking Out an Indian Patent

Section 64 of the Patents Act, 1970 is the post-opposition route to defeating an Indian patent. Where Section 25(2) post-grant opposition has a 12-month window from grant, Section 64 has no such limit — a revocation petition can be filed at any time during the life of the patent. The petition is filed in the appropriate High Court (the one with jurisdiction over the patentee or the cause of action), and the grounds are largely the same as those available in opposition, with a few additions.

This guide explains the grounds, the procedure, the standing requirement, and when revocation is the right tool — particularly for generic manufacturers, downstream users and competitors who have missed the post-grant opposition window.

The grounds — eleven categories

Section 64(1) lists eleven grounds for revocation, of which the most frequently invoked are:

• (a) Wrongful obtainment — the patentee obtained the invention from the petitioner
• (b) Prior claiming — the invention was claimed in an earlier valid Indian application
• (c) Prior public knowledge or use in India — before the priority date
• (d) Obviousness — the invention is obvious in light of prior art
• (e) Not an invention — within Sections 3 and 4. This is where Section 3(d), 3(j), 3(k) and method-of-treatment exclusions live
• (f) Insufficient or incorrect specification — the specification does not disclose the invention sufficiently or clearly
• (g) False or fraudulent claims in the application
• (h) Failure to disclose information required under Section 8 (foreign filings)
• (i) Convention application filed beyond the 12-month period
• (j) Failure to work the invention in India
• (k) Anticipated by traditional knowledge of any community

Section 64(1)(j) — failure to work — is unique to revocation; it is not available under Section 25 opposition. Section 64(2) adds further specialised grounds for patents granted in defiance of orders of the Central Government on national-security inventions.

Eleven doors lead to revocation. Find the one your patent forgot to lock.

Who can file — the 'person interested' standing

Section 64 limits standing to any 'person interested'. The Patents Act defines 'person interested' broadly to include any person engaged in or promoting research in the same field as the patent — encompassing competitors, generic manufacturers, research institutions, and trade associations in the relevant industry.

The Central Government can file revocation petitions under Section 66 on broader grounds, including patents inconsistent with the patentee's representations to the government or patents being used in a manner prejudicial to the public interest.

The forum and procedure

Section 64 petitions are filed in the High Court with territorial jurisdiction over the patentee or the cause of action. Following the 2021 abolition of the IPAB, this jurisdiction is exercised by the IP Division benches that have been established in several High Courts, with Delhi, Bombay, Calcutta and Madras seeing the highest volume of revocation matters.

The procedure is substantially evidence-driven. The petition sets out the grounds and supporting facts; the patentee files a counter-statement; evidence is filed by affidavit with documentary annexures and expert reports where the issues are technical. Cross-examination is allowed on affidavits where the High Court considers it necessary. Hearings are typically allotted multiple days for technical patent matters.

Section 64 in pharma practice

Indian generic manufacturers have used Section 64 extensively against follow-on pharma patents. The combination of ground (e) — non-invention under Section 3(d) — and ground (f) — insufficient specification — has produced multiple revocations of incremental polymorph and salt patents. The Section 3(d) framework read in Novartis v. Union of India is the substantive backdrop; Section 64 is the procedural vehicle.

Ground (h) — failure to disclose Section 8 information about foreign filings — has been a quietly powerful revocation ground. Foreign patentees who do not maintain meticulous Section 8 disclosures in their Indian prosecution risk revocation on this procedural ground alone, regardless of the substantive merits.

Counter-claim in an infringement suit

A defendant in a patent infringement suit can raise revocation as a counter-claim. Section 107 read with Section 64 enables this. The advantage: the validity and infringement issues are tried together in the same forum, on a single evidence record, with one final determination. The disadvantage: the defendant carries the cost burden of two simultaneous tracks. For commercially active patents, the counter-claim route is often more strategic than a stand-alone revocation petition.

Remedies and consequences

A successful revocation petition results in the patent being struck off the Register as if it had never been granted. The implications are significant — pending royalty obligations on licences may be revisited (subject to the licence terms); any pending infringement actions become non-actionable; and third-party generic launches that were waiting for the patent to fall can proceed. Revocation can be partial — claim-by-claim — where some claims survive and others fall.

The takeaway

Section 64 is the most powerful post-grant tool in Indian patent practice. Where Section 25(2) opposition has a hard 12-month deadline, Section 64 stays available for the patent's full term. The grounds are broad, the standing is reasonable, and the forum — the High Court IP Divisions — has developed substantial expertise in technical patent matters. For competitors, generics, downstream users and research bodies, the route is the structural check on weak or wrongly-granted patents. IPForte's patent prosecution and portfolio practice handles both sides — drafting patents to withstand 64 attack and bringing 64 petitions against vulnerable registrations.