Section 135 of the Patents Act, 1970
Convention applications
Allows an applicant who first filed in a convention country to claim that earlier date for an Indian application filed within twelve months.
Official legal text
The verbatim statutory text of this provision is reproduced from the official source and checked by our legal reviewer before it is published here. Until that check is complete for this page, read the exact wording directly from the official source linked below — it is the only version that governs.
This is a simplified explanation. Where it differs from the official text of the provision, or from an applicable Gazette notification, the official text and the notification prevail.
What this section says, in plain language
Section 135 contains the rule that most international patent planning is built around. Where a person has applied for protection of an invention in a convention country, and then applies in India within twelve months of that first application, the Indian application is a convention application and its claims may take the date of the earlier foreign filing. That earlier date is the priority date, and it is the date against which novelty and inventive step are judged for the claims that the earlier filing supports.
The right is not limited to the original applicant. A legal representative or an assignee of the person who filed abroad may make the Indian convention application, which matters because inventions are routinely assigned to a company, and companies are restructured. Where applications for the invention were made in two or more convention countries, the twelve month period is counted from the earliest of them, not from the most convenient one.
The section also allows related filings to be brought together. Where a person has made applications in convention countries for two or more inventions that are cognate, or where one is a modification of another, a single convention application may be made in India covering them, provided the matter fits together as one application. Section 137 then explains how the different claims take their dates when several basic applications are involved.
Priority does two things and not a third. It protects the applicant against material published, used or filed by others in the gap between the first filing and the Indian filing, and it fixes the date for testing each claim. It does not lengthen the term of the patent. Under section 53 the term is counted from the date of filing of the application in India, and in a national phase case from the international filing date, so an early priority claim does not shorten or extend protection in the way people sometimes assume.
Two practical requirements sit next to this section. A convention application must be accompanied by a complete specification and must identify the basic application, which is dealt with in section 136, and proof of the foreign filing may have to be furnished under section 138 and rule 21. Missing those steps can cost the priority claim even where the twelve month period was met.
Why this section matters
Foreign applicants entering India, Indian companies with an overseas first filing, and assignees who acquired rights after the first application.
During the twelve months after the earliest foreign filing, when the Indian application must be placed.
A right to have Indian claims judged on the earlier foreign filing date rather than the Indian filing date.
The Indian application stands on its own filing date, and anything published in the intervening months, including the applicant's own disclosures, can destroy novelty.
How it works in practice
A missed month changes the outcome for a battery casing
Kestrel Energy Systems, a fictional Indian-owned company incorporated in Singapore, files its first application for a modular battery casing in Singapore on 5 April. It intends to manufacture in Pune. The founders demonstrate the casing at a trade fair in October and a trade magazine publishes photographs and a description. The company's Indian counsel files the Indian convention application on 20 March the following year, within twelve months of the Singapore filing, with a complete specification identifying the Singapore application as the basic application. Because the claims take the April priority date, the October publication does not count as prior art against them. A second product, a coolant channel developed in August and never filed anywhere, is added as fresh claims in the Indian application. Those claims get the Indian filing date, and the examiner cites the October magazine article against them. The company keeps the casing claims and abandons the coolant claims, learning that priority protects only what the earlier filing actually disclosed.
Simplified illustration only. Actual legal outcomes depend on the facts.
Key points to remember
- An Indian application filed within twelve months of a first filing in a convention country may claim that earlier date.
- Where several basic applications exist, the twelve months runs from the earliest of them.
- A legal representative or assignee of the original applicant may make the convention application in India.
- Cognate inventions filed separately abroad may be combined in a single Indian convention application.
- Priority fixes the date for judging novelty and inventive step; it does not change how the term is counted under section 53.
- Only subject matter actually disclosed in the basic application enjoys the earlier date; new matter takes the Indian filing date.
Common mistakes and misunderstandings
- Counting the twelve months from the most recent foreign filing instead of the earliest one.
- Assuming priority covers everything in the Indian specification. It covers only what the basic application disclosed.
- Believing that a priority claim shortens the patent term. Term is reckoned under section 53 from the Indian filing date, or the international filing date in a national phase case.
- Filing a provisional specification with a convention application. Section 136 requires a complete specification.
- Claiming priority but never furnishing the certified copy or translation when required, which can lose the earlier date.
Connected provisions
This page explains a section of the Patents Act, 1970. The working detail that goes with it lives in the Patents Rules, 2003. The connected rules appear in their own block so that the statutory duty and the procedural steps stay clearly distinguishable when you cite either one.
Forms, deadlines and fees
Forms are not set out in the Act. They are prescribed in the Second Schedule to the Patents Rules and are revised from time to time, so obtain the current version from the official website before filing.
- The Indian convention application must be filed within twelve months of the earliest application made in a convention country.
- Where required, a certified copy of the basic application and a verified English translation must be furnished within the period set by rule 21, which should be checked in the current rules.
Open the deadline calculator — and have every date confirmed against the current Rules before you rely on it.
Fees are prescribed in the First Schedule to the Patents Rules. Because the Schedule is revised from time to time, and charges different amounts to different categories of applicant and for physical as against electronic filing, this page describes the fee without stating a figure. How Indian patent fees work.
Related judgments
Case law is added slowly and deliberately. A summary is drafted, checked against the reported judgment and then reviewed before publication, because a wrong case note can mislead a reader badly. No summary for this provision has reached publication yet. How case notes are prepared.
Questions people ask about Section 135
What is a convention application in India?
It is an Indian patent application that claims the date of an earlier application filed in a convention country. If it is filed within twelve months of that first foreign application and meets the formal requirements, the claims supported by the earlier disclosure are judged for novelty and inventive step as on the earlier date. It must be accompanied by a complete specification, must identify the basic application, and may need a certified copy and an English translation of that basic application.
How long do I have to file in India after filing abroad?
Twelve months from the earliest application for the same invention in a convention country. If you filed in more than one convention country, the clock runs from the first of them, not from the latest. Missing the twelve month window does not necessarily stop you from filing in India, but the application then stands on its own filing date, and anything published in the meantime, including your own product launch or paper, becomes prior art against it.
Does claiming priority reduce the life of my Indian patent?
No. The term under section 53 is twenty years from the date of filing of the application in India, and for an application that entered India from an international application it is counted from the international filing date. The priority date does its work in a different place, namely in deciding what counts as prior art for each claim. So an earlier priority date improves your position on novelty without eating into the term of the granted patent.
Can new matter be added to a convention application in India?
You can include additional subject matter in the Indian complete specification, but it will not enjoy the priority date. Those claims are tested from the Indian filing date, so publications and filings made after the foreign application can be cited against them. Where the added material is important, it is usually better to file a separate application for it, so the two sets of claims are examined cleanly rather than one weak claim dragging attention onto the whole file.
Can an assignee file the convention application instead of the original applicant?
Yes. Section 135 allows the application in India to be made by the person who applied in the convention country or by that person's legal representative or assignee. This matters in practice because inventions are commonly assigned to a company, and companies merge or restructure between the first filing and the Indian filing. Keep the chain of title documented, because proof of the applicant's entitlement can be required, and a gap in the chain is awkward to fix later.
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