Intellectual Property Rights - Law and Practice · Patent Documentation, Examination and Infringement

Opposition, Grant and Sealing of Patents in India

Updated 11 October 2026 · Fact-checked

Opposition lets a third party challenge a patent on grounds listed in section 25. Pre-grant opposition is made after publication but before grant, by any person. Post-grant opposition is made within one year of publication of grant, by a person interested. The Controller decides after hearing. Grant follows if no bar remains.

Understand Opposition, Grant and Sealing of Patents

A patent gives a monopoly. The law therefore lets outsiders object when a patent should not be given or should not stay. This objection is called opposition. Section 25 of the Patents Act, 1970 provides two routes, one before grant and one after.

Pre-grant opposition (section 25(1)) is available when the application has been published but a patent has not been granted. Any person may represent in writing to the Controller. There is no need to show any interest in the invention. The Controller hears the opponent if the opponent asks to be heard, and disposes of the representation in the manner and time prescribed.

Post-grant opposition (section 25(2)) can be filed at any time after grant but before one year from the date of publication of grant. Here the opponent must be a person interested. The Controller notifies the patentee and constitutes an Opposition Board of officers. The Board examines the notice and sends its recommendations. After hearing the patentee and the opponent, the Controller orders that the patent be maintained, amended or revoked (section 25(4)). If the patent is maintained subject to amendment, it stands amended accordingly (section 25(6)).

The grounds are the same list in both routes, clauses (a) to (k), and no other ground is allowed. They include wrongful obtaining, prior publication, prior claiming, public knowledge or use in India, obviousness, non-invention or non-patentable subject matter, insufficient description, non-disclosure of section 8 information, convention filing beyond twelve months, non-disclosure or wrong mention of biological source, and anticipation by traditional knowledge.

Grant and sealing sit at the end of the application process. When the application is in order and no bar remains, the Controller grants the patent and it is entered in the register and sealed with the seal of the Patent Office. The patentee then has the rights conferred by the Act, mainly the right to exclude others from making, using, offering for sale, selling or importing the patented product, or using the patented process, without consent. These grant, sealing and rights rules are not in the section text supplied here, so learn them from the ICSI material.

Key rules to remember

Pre-grant opposition: who and when: Any person; after publication of application, before grant (s. 25(1)); Made in writing to the Controller. The opponent is heard only if he requests a hearing.
Post-grant opposition: who and when: Person interested; after grant, before one year from publication of grant (s. 25(2)); Notice of opposition in the prescribed manner. Time runs from publication of grant, not the date of grant.
Post-grant procedure: Notice → Controller notifies patentee → Opposition Board → recommendation → hearing → order (s. 25(3), (4)); The Board only recommends. The Controller decides.
Controller's possible orders: Maintain, or amend, or revoke the patent (s. 25(4)); If amended, the patent stands amended accordingly (s. 25(6)).
Closed list of grounds: Clauses (a) to (k), 'but on no other ground'; Both routes use the same eleven grounds, with small wording changes for granted patents.
Evidence limit in post-grant: For grounds (d) and (e) of s. 25(2), ignore personal document, secret trial or secret use (s. 25(5)); Applies only to post-grant opposition on public use and obviousness.
Restoration of lapsed patent: Opposition only on: failure to pay renewal fee was not unintentional, or undue delay in applying (s. 61(1)); Do not mix with section 25 grounds.

How to solve Opposition, Grant and Sealing of Patents questions

Use this order for any problem or theory question on opposition, grant and sealing.

1Identify the stage: is the application published but not granted, or has the patent been granted? This fixes the route.
2State who may oppose: any person for pre-grant, a person interested for post-grant.
3Check the time limit: before grant for pre-grant; within one year of publication of grant for post-grant.
4Match the facts to a ground in clauses (a) to (k). Name the clause and quote its wording briefly.
5Check that the ground is within the list. If not, the opposition fails because of the words 'on no other ground'.
6Describe the procedure: Controller's hearing for pre-grant; notice, Opposition Board, recommendation and hearing for post-grant.
7Conclude with the order: maintain, amend or revoke for post-grant, and what follows for grant and sealing.
8Add one practical point, such as filing in writing, stating grounds clearly and keeping prior art documents ready.

Quickest way: Route, time, ground, order

When to use it: Use this in short-note questions or when you have under ten minutes for a case.

Write the route with the stage of the patent.
Write who can file and the deadline.
Name the matching ground clause.
Write the Controller's order and the effect.
Close with one line on sealing and patentee's rights if the patent survives.

Common mistakes in Opposition, Grant and Sealing of Patents

Saying only a person interested can file a pre-grant opposition.
Students blend the two sub-sections.
Fix: Remember: pre-grant means 'any person'; post-grant means 'any person interested'.
Counting the one-year period from the date of grant.
The word 'grant' is noticed and 'publication of grant' is missed.
Fix: Write: before expiry of one year from the date of publication of grant.
Adding grounds such as lack of industrial applicability or public interest.
Students use grounds from revocation or general knowledge.
Fix: Use only clauses (a) to (k). The section says 'but on no other ground'.
Saying the Opposition Board decides the case.
The Board's role is confused with the Controller's.
Fix: The Board examines and recommends. The Controller orders after hearing both sides.
Saying the Controller can only maintain or revoke.
Amendment is forgotten.
Fix: There are three orders: maintain, amend or revoke. An amended patent stands amended.
Applying section 25 grounds to opposition against restoration of a lapsed patent.
All oppositions seem alike.
Fix: Under section 61, only two grounds exist: failure to pay was not unintentional, or undue delay.

Worked examples

Example 1

Bharat Pharma Ltd has applied for a patent for a drug formulation. The application is published and no patent is granted yet. Sunita, a researcher with no business in the field, finds a 2015 journal article in Germany that describes the same formulation. Can she oppose, and on what ground?

Show the solution

Stage: the application is published and no patent is granted, so section 25(1) applies.
Who: any person may oppose. Sunita need not show any interest.
Ground: the invention was published in a document in India or elsewhere before the priority date. This is section 25(1)(b)(ii), unless section 29(2) or (3) makes the publication not an anticipation.
The ground may also support a plea of no inventive step under clause (e) if the article only nearly matches.
Procedure: she files a representation in writing to the Controller, and if she requests, the Controller hears her and disposes of the representation as prescribed.

Answer: Yes. Sunita can file a pre-grant opposition under section 25(1) as any person, on the ground of prior publication under clause (b)(ii), and may also plead lack of inventive step under clause (e).

Example 2

A patent was granted to Kaveri Tech Pvt Ltd and its grant was published on 10 March. Rohan Industries, a competitor, wants to oppose it on the ground that the specification does not sufficiently describe the invention. Explain the right, time limit and likely procedure.

Show the solution

Stage: the patent is granted, so section 25(2) applies.
Who: Rohan is a competitor, so it is a person interested and may give notice of opposition.
Time: the notice must be given before one year from the date of publication of grant, that is before 10 March of the next year.
Ground: insufficient description is clause (g) of section 25(2), which is a valid ground.
Procedure: the Controller notifies Kaveri Tech and constitutes an Opposition Board. The Board examines the notice and sends its recommendations.
Decision: after hearing Kaveri Tech and Rohan, the Controller orders that the patent be maintained, amended or revoked. If amended, the patent stands amended accordingly.

Answer: Rohan may file a post-grant opposition under section 25(2)(g) before one year from publication of grant. The Controller decides after the Opposition Board's recommendation and a hearing, by maintaining, amending or revoking the patent.

Exam tips

Draw a two-column comparison in your answer: stage, who can file, time, procedure and outcome. It shows the difference clearly.
In case questions, name the exact clause letter of the ground. Markers look for it.
Always write 'on no other ground' when a student proposes an outside reason for opposition.
For post-grant questions, mention the Opposition Board and that the Controller gives the final order after hearing.
Keep section 61 and section 87 separate: they deal with restoration and with compulsory licence related applications, not ordinary opposition.

Practice questions from Patent Documentation, Examination and Infringement

Opposition, Grant and Sealing of Patents: frequently asked questions

What is the difference between pre-grant and post-grant opposition?

Pre-grant opposition is filed by any person after publication of the application but before grant. Post-grant opposition is filed by a person interested within one year from publication of grant. The post-grant route also involves an Opposition Board.

What are the grounds of opposition under section 25?

There are eleven grounds in clauses (a) to (k). They cover wrongful obtaining, prior publication, prior claiming, public knowledge or use, obviousness, non-patentability, insufficient description, non-disclosure under section 8, late convention filing, biological source defects and traditional knowledge anticipation. No other ground is allowed.

Can the Controller amend a patent after opposition?

Yes. After the hearing, the Controller may maintain, amend or revoke the patent. If the patent is maintained subject to amendment, it stands amended accordingly.

Is the time limit for post-grant opposition counted from grant?

No. Section 25(2) counts one year from the date of publication of grant. Read the wording carefully in the exam.