Sections 18 explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
These three sections give the Controller specific powers at the examination stage. Section 18 applies when the examination finds that the invention has been anticipated. Section 19 applies when the invention cannot be performed without a substantial risk of infringing another patent. Section 20 applies when someone else claims the right to the application, or joint applicants fall out. Each gives the applicant a way to answer the point, so these provisions shape any patent objection reply.
Section 18: if an invention is anticipated as found under section 13, the Controller may refuse the application unless the applicant shows an earlier priority date or amends; for a prior claim he may direct a reference to the other specification be inserted as notice to the public. Section 19: where the invention cannot be performed without substantial risk of infringing another patent, he may direct a reference to that patent unless the applicant contests validity on reasonable grounds or amends. Section 20: before grant, he may substitute or add applicants on a proper claim and settle disputes between joint applicants.
Section 18: anticipation
Section 18(1): anticipation by prior publication
Where it appears to the Controller that the invention, as claimed in any claim, "has been anticipated in the manner referred to in clause (a) of sub-section (1) or sub-section (2) of section 13", he "may refuse the application" unless the applicant (a) shows that the priority date of the claim is not later than the date on which the relevant document was published, or (b) amends the complete specification to the Controller's satisfaction.
The anticipation here is under section 13(1)(a) (Indian specifications published before filing) or section 13(2) (any other document in India or elsewhere); see our article on section 13. The Controller "may refuse" unless the applicant either:
- (a) shows that the claim's priority date is not later than the date of publication of the relevant document, in which case the document is not earlier than the claim; or
- (b) amends the complete specification to the Controller's satisfaction.
The words "the application" in "he may refuse the application" replaced the earlier words about refusing to accept the complete specification, in 2005.
Section 18(2): prior claim in another specification
Where the invention is claimed in another complete specification of the kind in section 13(1)(b), the Controller "may" direct that a reference to it be "inserted by way of notice to the public in the applicant's complete specification" unless, within such time as may be prescribed, the applicant shows that his priority date is not later than that of the other claim, or amends the specification to the Controller's satisfaction. Here the consequence is softer than refusal: a reference to the other specification is inserted in the applicant's complete specification "by way of notice to the public". The applicant avoids that by showing an equal or earlier priority date, or by amendment, within the prescribed time.
Section 18(3): a prior claim found on or after the priority date
Where the Controller finds that the claimed invention is claimed in an Indian specification of the kind in section 13(1)(a) and that specification was published on or after the applicant's priority date, the section 18(2) route applies in the same manner, unless the applicant shows that his priority date is not later than that of the other claim. Sub-section (4) was omitted by the 2005 Act, so the section ends at (3).
Example. Rangoli Textiles (fictional) claims a fabric treatment. The examiner finds a foreign journal article published in March describing the same treatment. The company's claim has a priority date in June. Under section 18(1) the Controller may refuse the application unless the company shows that its priority date is not later than the article's publication date (it cannot) or amends the claim to the Controller's satisfaction (it narrows the claim to a feature the article does not disclose).
Section 19: potential infringement
Section 19(1)
If, in consequence of the investigations, the Controller finds that the invention "cannot be performed without substantial risk of infringement of a claim of any other patent", he may direct a reference to that patent to be inserted in the complete specification "by way of notice to the public", unless within the prescribed time the applicant shows reasonable grounds for contesting the validity of the claim, or amends. The test is "cannot be performed without substantial risk of infringement". The Controller's remedy is again a notice: a reference to the other patent. The applicant can avoid it by showing "reasonable grounds for contesting the validity" of the claim, or by amendment. The words "under this Act" replaced earlier words about the foregoing provisions and proceedings under section 25 in 2005.
Section 19(2): deleting the reference
Once a reference has been inserted, the applicant may ask the Controller to delete it if (a) the other patent is revoked or otherwise ceases to be in force, (b) the relevant claim is deleted by amendment, or (c) it is found, in proceedings before the court or the Controller, that the relevant claim is invalid or is not infringed by any working of the applicant's invention. The Controller "may" delete.
Section 20: substitution of applicants and joint-applicant disputes
Section 20(1): claimant to the application
A person who, "by virtue of any assignment or agreement in writing made by the applicant or one of the applicants ... or by operation of law", would be entitled to the patent, the applicant's interest or an undivided share if it were then granted, may make a claim in the prescribed manner at any time before grant. If the Controller is satisfied, he "may" direct that the application proceed in the claimant's name, or in the names of the claimant and the other applicants.
Section 20(2) and (3): limits
- (2): no direction on the strength of an assignment or agreement by one of two or more joint applicants "except with the consent of the other joint applicant or applicants".
- (3): no direction on an assignment or agreement for the assignment of the benefit of an invention unless (a) the invention is identified by the application number, or (b) the person who made it acknowledges that it relates to the invention in the application, or (c) the claimant's rights have been finally established by a court, or (d) the Controller gives directions under sub-section (5) for enabling the application to proceed.
Section 20(4): death of a joint applicant
If one of two or more joint applicants dies before grant, the Controller may, on a request by the survivor or survivors and with the consent of the legal representative of the deceased, direct that the application proceed in the survivor's name alone.
Section 20(5): disputes between joint applicants
If a dispute arises between joint applicants whether or in what manner the application should be proceeded with, the Controller may, on application in the prescribed manner by any party, "and after giving to all parties concerned an opportunity to be heard", give such directions as he thinks fit, including that it proceed in the name of one or more of the parties alone.
Example. Asha and Imran, fictional co-applicants, disagree on whether to continue their application. After hearing both, the Controller may direct that it proceed in Asha's name alone. If Imran had assigned his share to a company without Asha's consent, section 20(2) bars a direction on that assignment unless Asha consents.
Summary table
| Section | Trigger | Controller's power | Applicant's way out |
|---|---|---|---|
| 18(1) | Anticipation by publication | May refuse the application | Earlier-or-equal priority date; amend |
| 18(2), (3) | Prior claim in another specification | Direct reference as notice to the public | Earlier-or-equal priority date; amend, within prescribed time |
| 19(1) | Substantial risk of infringing another patent | Direct reference to that patent | Reasonable grounds to contest validity; amend, within prescribed time |
| 19(2) | Reference inserted; later events | May delete reference on applicant's application | Revocation, claim deleted, or finding of invalidity or non-infringement |
| 20 | Claimant, death, or dispute | Substitute applicants or give directions | Consent, proof, hearing |
The sections give no figure for the "prescribed" time in sections 18(2) and 19(1), and do not say how a notice to the public is worded.
Need help with ...?
When the Controller raises anticipation or a conflicting patent, the response usually combines evidence on dates with careful amendment. Our team can help prepare it as part of patent objection reply work. For examples of common objections see our post on common patent application rejections.
Key takeaways
- Under section 18 the Controller may refuse an application anticipated by publication unless the applicant shows an earlier or equal priority date or amends.
- For prior claims, he may direct a reference to the other specification as notice to the public.
- Under section 19 he may direct a reference to another patent if the invention cannot be performed without substantial risk of infringement, unless validity is reasonably contested or the specification is amended.
- Under section 20 he may substitute or add applicants before grant and settle joint-applicant disputes, after hearing all parties.
Read next
- Section 21: time for putting application in order for grant
- Section 15: power to refuse or require amendment
- Section 13: search for anticipation
- Response to the first examination report
Disclaimer: Based on the Patents Act, 1970 as amended up to the Jan Vishwas (Amendment of Provisions) Act, 2023, as consulted on 1 October 2026. Forms, fees and time limits under the Patents Rules, 2003 change from time to time and are not covered here. This article is general information, not legal advice; check the official text before acting.