Filing data after applying for an Indian patent: Drafting and practice insights

Applying for a patent is a race against time to secure the earliest priority date (i.e., the date of the first filing of a patent application). As a result, patent applications are often filed with accompanying data that do not always capture all the facets of the invention. In such cases, using post-filing data to support the applications is often the only course available. However, the admissibility and treatment of post-filing data at the Indian Patent Office (IPO) has not always been clear.

Recent judgments at the Intellectual Property Appellate Board (IPAB) and the Delhi High Court have shed some light on this issue, tackling important questions such as: (1) Is post-filing data generally accepted at the IPO; and (2) under what circumstances can post-filing data be considered admissible or, conversely, inadmissible.

Does the IPO accept post-filing data?

The short answer to this question is: yes, post-filing data is accepted at the IPO.

Citing that this was common practice in foreign jurisdictions as well, a recent decision at the IPAB (OA/33/2015/PT/KOL) clarified:

Filing of additional documents, data and evidence in support of the invention, to overcome the objection raised and to attack a specific objection is something which is allowed under the Patent Law of not only India but also other foreign jurisdictions“.

The Delhi High Court reaffirmed the acceptance of post-filing data in its decision in  Astrazeneca vs Intas Pharma (MANU/DE/1939/2020):

The plaintiffs’ argument that post filing data relating to the invention is admissible is based on two grounds: (i) First and foremost, the applicant may not be fully aware of the advances and properties of the subject invention, in this case, the compound DAPA, on the priority date. In this behalf, it is stated that DAPA’s properties for treatment of heart failure came to be known only subsequently. (ii) Second, there is no requirement in law that all properties, advantages, and characteristics should be stated on the filing date of the patent application“.

In these decisions, affidavits, declarations, and (in the former case) clinical trial data demonstrating the technical advance/advantages and efficacy data, were used to overcome inventive step issues and/or patentability objections under Sections 3(d) and 3(e) of the Indian Patents Act, 1970 (the Act).

In the IPAB case, the additional data along with the data in the specification were deemed sufficient to overcome the hearing objections, thus setting aside the Controller’s refusal of the application. In the latter case, the Delhi High Court refused to accept the additional data as proof for “inventive step” citing the absence of such data in the first place in the original specification.

This brings us to the second question, as to the circumstances under which post-filing data is considered admissible or inadmissible.

Admissibility of post-filing data

The thumb rule appears to be that it is permissible to submit additional data so long as it has some prior basis in the specification already filed.

In Astrazeneca, the Court’s decision offers some guidance on when post-filing data cannot be taken on record:

[P]ost priority date evidence ….  to show technical advance can only be taken into account to confirm the existence of technical effect which is found embedded in the specification of IN625 and is capable of being understood by a skilled person having common general knowledge and not to rely upon the same to establish its effect for the first time

In reference, the decision also cited the following paragraph from Generics (UK) Limited vs. Yeda Research and Development Company Limited ([2017] EWHC 2629 (Pat); [2018] R.P.C. 2)

…I must briefly address the Defendants’ reliance upon evidence which post-dates the priority date of the Patent. It is common ground that such evidence can only be relied upon to confirm the existence of a technical effect which is plausible in the light of the specification and the skilled person’s common general knowledge, and not to establish the existence of a technical effect for the first time

Whilst the IPAB decision did not clarify the circumstances under which data would not be admissible, it did cite the following paragraph:

“In re Khelghatian, 53 CCPA 1441, 364 F.2d 870, 876 (1966) – holding the claimed invention non-obvious in view of post-filing evidence of an unexpected property not disclosed in the specification, while noting that the evidence “[wa]s directed to that which ‘would inherently flow’ from what was originally disclosed [with emphasis]

From this, it can be inferred that, at least in the case of data demonstrating inventive step, additional data which supports what is already described in the specification, is more likely to be accepted than entirely new experimental data which lacks basis in the specification.

The situation in the case of comparative experimental data to overcome Section 3 objections, specifically Sections 3(d) and 3(e), is still a little unclear.

The Manual Of Patent Office Practice And Procedure (Version 3.0, 1 March 2019) states that “the complete specification shall bring out clearly and categorically in the description, as to how the subject matter differs significantly in properties with regard to efficacy from the known substance at the time of filing of the application or subsequently by way of an amendment of specification under section 59.”

This indicates that post-filing efficacy data should be within the scope of the originally-filed specification. Indeed, in a previous judgement (TRA/7/2007/PT/KOL), the IPAB stated that “If a synergistic effect is to be relied on, it must be possessed by everything covered by the claim, and it must be described in the specification.”

However, in a more recent case (OA/6/2015/PT/MUM), the IPAB accepted efficacy data submitted for a Section 3(d) objection, even though the stated properties of the claimed compounds were not discussed in the specification. That said, in this case, the compounds were considered novel and therefore, the IPAB also concluded that the objection under Section 3(d) was erroneously invoked.


The recent judgements at the IPAB and Delhi High Court unequivocally permit reliance on post-filing data to address objections or to provide evidence for the superior advantages of the invention.

However, there is still ambiguity regarding the circumstances under which such post-filing data to be taken into consideration. In general, such data must be within the scope of the claims. Ideally, applicants are also advised to disclose at least some data relating to technical effect, and experimental data regarding efficacy, and/or comparative examples in the specification. In the absence of such experimental data at time of filing the specification, the specification should be drafted in a manner such that the technical effect can be inferred from the disclosure. This is so that any experimental data added subsequently would find some basis in the specification. These drafting practices may improve the likelihood of acceptance of such post-filing data.