Patent Opposition (Pre-Grant and Post-Grant)

A patent opposition is a proceeding before the Indian Patent Office in which a third party challenges the grant of a patent. It is a critical tool for competitors, generic pharmaceutical companies, and public-interest groups to prevent the grant of patents that should not have been allowed.

Indian law provides two types of opposition: pre-grant (before the patent is granted) and post-grant (within one year of the grant publication). Each has different grounds, procedures, and strategic implications.

Pre-grant opposition — Section 25(1)

A pre-grant opposition can be filed by any person after the patent application is published (18 months from filing or priority date) but before the patent is granted.

Grounds for pre-grant opposition (Section 25(1)(a)–(k))

Procedure for pre-grant opposition

1. File written representation (Form 7A) with the Controller
2. Controller considers representation and may either reject it or refer it to the applicant for reply
3. Applicant files reply (typically within 3 months)
4. Opponent files evidence in support
5. Applicant files evidence in reply
6. Hearing before the Controller
7. Controller’s decision — grant or refuse the application

Timeline for pre-grant opposition

Pre-grant oppositions typically take 18-36 months from filing to decision, though timelines vary significantly by jurisdiction and complexity.

Post-grant opposition — Section 25(2)

A post-grant opposition can be filed by any person interested within one year from the date of publication of the grant of the patent.

“Person interested”

A “person interested” is defined broadly. It includes:

• Persons engaged in, or promoting, research in the same field
• Competitors
• Consumer groups and public interest bodies
• Any person who can show a commercial, public interest, or personal stake in the outcome

Grounds for post-grant opposition

The grounds are the same as for pre-grant opposition (Section 25(2) incorporates the grounds of Section 25(1) by reference), with one addition: the opponent can challenge the patent on any ground on which a patent could have been revoked under Section 64.

Procedure for post-grant opposition

1. File Notice of Opposition (Form 7) within one year of grant publication
2. Controller serves notice on the patentee
3. Patentee files reply statement (typically within 2 months)
4. Opponent files evidence in support
5. Patentee files evidence in reply
6. Opponent files evidence strictly in reply (if needed)
7. Hearing before the Opposition Board or the Controller
8. Decision — maintain, amend, or revoke the patent

Pre-grant vs post-grant — strategic comparison

Key strategic considerations

For the opponent

• Monitor patent publications actively. The pre-grant window is the most cost-effective time to oppose
• Prepare prior art search before filing. Strong prior art is the foundation of any opposition
• Consider multiple grounds in the alternative — anticipation, obviousness, and Section 3(d)
• Budget for the long haul — oppositions typically take 2-3 years

For the applicant/patentee

• File a robust specification with detailed examples and strong claims
• Comply with Section 8 — disclose all foreign applications promptly
• Respond strategically — amend claims if possible to overcome objections
• Consider settlement — in some cases, a licence or coexistence agreement is preferable to prolonged opposition

After the Controller’s decision

Appeal

An appeal against the Controller’s decision in opposition proceedings lies to the High Court having territorial jurisdiction, following the abolition of the IPAB under the Tribunals Reforms Act, 2021.

Revocation (Section 64)

If the post-grant opposition window has closed, any person interested may file a petition for revocation before the High Court on any of the grounds specified in Section 64. Revocation proceedings are typically more formal and expensive than opposition.

Common misconceptions

“Pre-grant opposition is informal and not serious”

False. Pre-grant opposition is a full statutory proceeding. The Controller examines the representation seriously and may refuse the application based on the opponent’s submissions.

“I can oppose at any time after grant”

False. The post-grant opposition window is one year from the date of publication of the grant. After that, the remedy is revocation under Section 64 before the High Court.

“Only competitors can oppose”

False. For pre-grant opposition, any person can file. For post-grant, “any person interested” includes competitors, consumer groups, research institutions, and public interest bodies.

“Opposition always delays the patent significantly”

Often true, but not always. If the opposition is weak, the Controller may dispose of it quickly. Strong oppositions, however, typically add 2-3 years to the prosecution timeline.

Frequently raised questions

Can I file both pre-grant and post-grant opposition?

Technically yes, but practically: if you file a pre-grant opposition and the patent is granted despite it, you can file a post-grant opposition (if within the one-year window). However, many grounds raised in the pre-grant opposition cannot be re-litigated in the post-grant opposition.

What happens to the patent during opposition?

The patent application (pre-grant) or the granted patent (post-grant) remains suspended during the opposition proceedings. The applicant cannot enforce the patent, but third parties are also not free to use the invention.

Can the patentee amend claims during opposition?

Yes — the patentee may amend the specification or claims, but only by way of explanation, correction, or disclaimer. The amendment cannot claim new matter or broaden the scope of the claims.

What is the success rate of patent oppositions?

Success rates vary by field. In the pharmaceutical sector, where Section 3(d) and prior art challenges are common, opposition success rates are significant. In mechanical and electrical fields, success rates are lower.

How much does a patent opposition cost?

Costs vary widely depending on complexity:

• Pre-grant opposition: ₹1.5–4 lakhs (including professional fees and limited prior art search)
• Post-grant opposition: ₹3–8 lakhs (more formal, full evidentiary proceedings)
• Revocation (Section 64): ₹5–15 lakhs (High Court proceedings)

Related entries

• Patentability Criteria — the grounds most commonly relied upon in opposition
• Compulsory Licence — an alternative mechanism for access to patented inventions
• See practice area: Intellectual Property