Revocation vs Opposition: The Routes to Attack an Indian Patent
There is more than one way to challenge an Indian patent, and the routes are not interchangeable. Opposition under section 25 happens at the Patent Office, inside two narrow windows tied to publication and grant. Revocation under section 64 happens in the High Court, and it stays available for as long as the patent is in force. Add the special revocation powers in sections 65, 66 and 85 and there are several distinct doors, each with its own key.
The reason people confuse them is that the grounds overlap heavily. Lack of novelty, obviousness, section 3 subject matter, insufficient description, wrongful obtaining and failure to give information about foreign applications appear in both lists. So a challenger who has good material often has a real choice, and the question becomes forum and timing rather than argument.
Getting that choice wrong is expensive. The post-grant opposition window closes twelve months after the grant is published and does not reopen. A revocation petition filed in the wrong circumstances invites a jurisdictional fight before anyone reaches the merits. This page sets out what each route is, when each is available, and how they interact with an infringement suit.
Side by side
| Question | Revocation (section 64) | Opposition (section 25) |
|---|---|---|
| Forum | The High Court, on a petition, or the same court hearing an infringement suit by way of counterclaim. | The Controller at the Patent Office. |
| When it is available | At any time while the patent is in force. | Pre-grant: after publication and before grant. Post-grant: within twelve months from publication of the grant. |
| Who may bring it | A person interested, or the Central Government, or a defendant in an infringement suit as a counterclaim. | Pre-grant: any person. Post-grant: a person interested. |
| What is being attacked | A patent that already exists and is enforceable. | Pre-grant: an application that has not yet become a patent. Post-grant: a granted patent. |
| Who decides | A judge, applying civil procedure and the law of evidence. | The Controller, assisted in a post-grant case by an Opposition Board of examiners. |
| Evidence | Pleadings, documents, witness evidence and expert testimony, with cross-examination. | Documentary evidence and affidavits filed in a prescribed sequence, with limited scope for further evidence. |
| Grounds | A long statutory list including want of novelty, obviousness, section 3 subject matter, insufficiency, wrongful obtaining, false suggestion, non-disclosure of foreign application information and filing abroad without permission. | A closely parallel list, with the pre-grant and post-grant grounds drawn in similar terms. |
| Possible outcome | The patent is revoked, in whole or in part, or the petition is dismissed. Amendment may be allowed in the proceeding. | Pre-grant: the application is refused or amended before grant. Post-grant: the patent is revoked, maintained, or maintained as amended. |
| Effect while pending | The patent remains in force and enforceable unless the court orders otherwise. | The application or patent proceeds normally; a pending opposition does not suspend the patentee's rights. |
| Typical duration and cost | Long and expensive, comparable to other High Court litigation. | Shorter and lighter, particularly the pre-grant route. |
| Relationship to an infringement suit | Directly connected. Validity can be raised as a counterclaim, and grounds of revocation are also available as defences. | Independent of any suit. An opposition before the Controller does not decide an infringement claim. |
| Special variants | Sections 65, 66 and 85 give separate powers: atomic energy directions, revocation in the public interest, and revocation for non-working after a compulsory licence. | None. Section 25 has only the pre-grant and post-grant routes. |
What revocation under section 64 covers
Section 64 sets out the grounds on which a patent can be taken off the register. The list is long and it covers more than the technical merits. Alongside want of novelty, obviousness and unpatentable subject matter, it includes grounds such as the patent having been obtained wrongfully, the specification not describing the invention sufficiently, the claims not being clearly defined, false suggestion or representation, failure to disclose information about foreign applications, and applying abroad without the permission required for residents of India.
That breadth is why revocation is often the stronger weapon. A patent may be perfectly good on the technology and still be vulnerable on procedure or on disclosure obligations.
The petition goes to the High Court. Since the Tribunals Reforms Act, 2021 abolished the Intellectual Property Appellate Board, the jurisdiction that Board held has moved to the High Courts, so that is where revocation petitions and rectification applications are now heard.
What opposition under section 25 covers
Opposition is the Patent Office route. Before grant, anyone may file a representation once the application is published. After grant, a person interested has twelve months from publication of the grant to file a notice of opposition. The grounds available run closely parallel to the revocation grounds.
The advantage is the decision maker. The Controller and the Opposition Board are technically qualified and read specifications every day. A well-chosen piece of prior art often lands harder there than it would in a court that is meeting the technology for the first time.
The limitation is the window. Both routes are time-bound in a way revocation is not, and once the post-grant period passes there is no application for extension that reopens it.
The special revocation powers
Three provisions sit outside the ordinary contest between private parties. Section 65 deals with patents connected to atomic energy, where the Central Government can direct revocation or amendment. Section 66 allows the Central Government to revoke a patent it considers mischievous to the State or generally prejudicial to the public, after giving the patentee an opportunity to be heard.
Section 85 is different again. Where a compulsory licence has been granted and the patented invention still is not worked in India, or reasonable requirements of the public are still not met, the Controller may revoke the patent on an application made after the period the Act specifies. This route belongs with the working and compulsory licensing provisions rather than with ordinary validity attacks.
None of these is a substitute for section 64. They exist for narrow situations and are rarely the answer for a competitor with prior art.
How the routes interact with an infringement suit
The most common way validity gets tested in India is not a standalone petition at all. It is a counterclaim. When a patentee sues, the defendant can both defend the claim and ask the court to revoke the patent, and the grounds of revocation are also available as defences in the suit.
This changes the calculation for a challenger who expects to be sued anyway. Filing a revocation petition first can secure a forum and put the patentee on the back foot. Waiting and raising the counterclaim keeps costs down but leaves the timing in the patentee's hands.
There is also a point about interim relief. A pending opposition or revocation proceeding does not stop the patentee acting on the patent. A defendant who needs the patent held back has to persuade a court, and the existence of a serious validity challenge is one of the things a court weighs when deciding whether to grant an injunction.
Which route to reach for
Start with what is still open. If the patent has not been granted, only the pre-grant route exists. If grant was published within the last twelve months, both post-grant opposition and revocation are on the table. If more than twelve months have passed, opposition is gone and section 64 is the route.
Then look at the evidence. Documentary prior art suits the Patent Office. A case that depends on proving what a machine did on a factory floor in 2016, or on an expert explaining what a skilled person would have thought, needs a forum with cross-examination.
Finally, consider what result you need. An opposition decision resolves the patent's fate at the office. A High Court judgment carries broader authority and is usually what a party facing a serious commercial threat wants.
Which one applies to you
Revocation (section 64)
- The twelve-month post-grant opposition window has already closed.
- Your case needs witnesses, cross-examination or expert evidence that affidavits alone cannot carry.
- You are already being sued, or expect to be, and validity can be raised as a counterclaim.
- You want a binding judicial determination rather than an office decision.
Opposition (section 25)
- The application is published and not yet granted, so a pre-grant representation is still possible.
- The grant was published within the last twelve months and you qualify as a person interested.
- Your strongest material is documentary prior art that a technically qualified reader can assess quickly.
- You want a lower-cost challenge before committing to High Court litigation.
Where people go wrong
- Assuming revocation and opposition are alternatives that stay open equally. Opposition has hard windows; revocation runs for the life of the patent.
- Filing a revocation petition without being a person interested. Standing is a threshold question and gets tested early.
- Thinking a pending challenge freezes the patent. The patent stays in force and enforceable while opposition or revocation is pending, unless a court orders otherwise.
- Overlooking the non-technical grounds in section 64, such as failure to disclose foreign application information or filing abroad without the required permission.
- Confusing section 66 revocation in the public interest, which is a Central Government power, with an ordinary validity challenge between competitors.
The window that closed, and the counterclaim that opened
Here is a simplified illustration, built from invented facts rather than a real dispute. Halcyon Valves Pvt Ltd in Rajkot learns that a competitor holds a patent on a pressure relief mechanism it has been building for years. By the time its counsel looks at the file, the grant was published nineteen months earlier, so the post-grant opposition window has closed. Halcyon has two useful things: a Japanese catalogue from before the priority date, and three former employees of a Bhavnagar foundry who can say they machined the same mechanism in 2014. The catalogue would have suited an opposition. The foundry evidence never would, because it needs witnesses who can be questioned. When the competitor sues Halcyon for infringement, Halcyon defends and files a counterclaim for revocation, putting both the catalogue and the prior use evidence before the High Court in one proceeding. The closed window cost it a cheaper route, not its case.
Simplified illustration only. Actual outcomes depend on the facts.
Questions people ask
Can I file a revocation petition and a post-grant opposition at the same time?
Running both against the same patent at the same time creates an obvious problem: two forums considering the same grounds. Indian practice discourages parallel attacks on the same subject matter, and a party that does this can expect the point to be raised against it. The practical approach is to pick the forum that suits the evidence and the timeline. If the opposition window is open and the case is documentary, use it. If the case needs witnesses or the window has closed, go to the High Court.
Do I need to be sued before I can seek revocation?
No. A person interested can file a revocation petition in the High Court without waiting for the patentee to act. Being sued simply opens a second route, because validity can then be raised as a counterclaim in the same suit and the grounds of revocation are also available as defences. Which is better depends on your position. Filing first gives you control of timing and forum. Waiting is cheaper but leaves the initiative with the patentee.
Are the grounds identical in opposition and revocation?
They overlap heavily but they are not word for word the same, and you should check the current text of section 25 and section 64 for the case in hand. Both lists cover want of novelty, obviousness, subject matter falling within section 3, insufficient description, wrongful obtaining, and failure to comply with the disclosure obligations about foreign applications. The practical difference is less about which grounds exist and more about what evidence each forum can properly receive to prove them.
What is revocation for non-working under section 85?
It is a separate route tied to the compulsory licensing scheme rather than to validity. Where a compulsory licence has already been granted and the patented invention is still not worked in India, or the reasonable requirements of the public are still not satisfied, or it is not available at a reasonably affordable price, the Controller may revoke the patent on an application made after the period the Act specifies. It is not a way for a competitor to attack a patent on prior art.
If a patent is revoked, what happens to past acts?
Revocation removes the patent, and the practical consequence is that the exclusive right it conferred can no longer be enforced. The effect on transactions and proceedings that took place while the patent stood is a question courts address on the facts, and it can be affected by things like settled licence payments and concluded suits. This is exactly the kind of question that turns on the specific record, so it needs to be looked at against the actual documents rather than answered in general terms.
Weighing an opposition against a revocation petition?
MYCrave Consultancy checks which windows are still open and which forum suits the evidence you actually hold.