Evidence at different stages under the Indian Patents Act

17 Nov 2023 | Newsletter

Mohan Dewan
Mohan DewanRK Dewan & Co, India

Evidence is simply anything that is utilized to acknowledge or explain the truth of submission and every kind of evidence is considered important to determine the outcome of a case. Whether it is a civil or a criminal case, evidence plays a significant role as the proof of a fact will not be effective without having any evidence in support of the fact.

Evidence can be furnished at the different stages of a patent application prosecution before the Patent Office, or in infringement or revocation actions at the Courts. Before the Patent office it can be submitted:

  1. while filing Reply to FER,
  2. while filing Reply to Section 14/15 Hearings,
  • During filing of a Review Petition to point out the error apparent in the decision and may be also to justify the data already filed or in specification,
  1. During the Pre-grant Opposition prosecution under section 25(1) both by Applicant as well as an Opponent,
  2. During the Post-grant Opposition prosecution under section 25(2) both by Applicant as well as the Opponent.

Evidences can be also filed before High courts during revocation proceedings, counter claim proceedings or infringement and revocation proceedings.

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 data that does not always capture all the facets of an invention. In such cases, using post-filed data to support an invention is often the only course available. However, the admissibility and treatment of post-filed data at the Indian Patent Office (IPO) has not always been clear.

Before the Patent Office mostly the data can be submitted after filing of the application and is filed in the form of an Affidavit/Declaration. Intellectual Property counsels often face the dilemma of when to file a patent application: as soon as possible, or wait and gather more support? Filing an application “early” helps to avoid anticipatory prior art but if the application is filed too early, the applicant may risk a rejection during examination for lack of supporting evidence.

On the other hand, if the application is filed too late, the applicant may lose the priority date. This is especially problematic for bio-pharma industry applicants where on the one hand, data is often critical for securing a patent; on the other hand, the research and development cycle is long and generating experimental and clinical trial data requires significant resources and time. Frequently supporting data is not available until long after the application is filed. Filing a series of provisional applications when data is available does not always remedy the problem. The applicant is left with a difficult decision- whether or not to convert a provisional specification to a complete specification and faces more problems in filing a PCT application. Further complicating this difficult decision is that not all jurisdictions treat post-filed data in the same manner; even in the same patent office, patent examiners do not treat all post-filed data in the same way. This can cause confusion and uncertainty for an applicant seeking to obtain global patent portfolios.

There are no principles outlined in the manual of the Indian Patent Office (IPO) for acceptance or rejection of post-filed data in general. Also, there is no consistent line of judicial precedents that have conclusively dealt with the issue of considering post-filed data as acceptable. Thus, such data’s acceptability is at the discretion of the examining Controllers, and there is no uniformity among Controllers at the Indian IPO.

The issue of post-filed data for the purpose of establishing inventive step has specifically come to be considered at the Intellectual Property Appellate Board (IPAB) (now abolished). The IPAB took the stand that the Patents Act, 1970 does not allow for such data to be considered to establish inventive step. The IPAB while analyzing submissions in support of post-filed data had held that under the Patents Act, 1970, a patent is revoked if the invention is shown to be obvious and such a conclusion cannot be altered by relying upon any secondary considerations. Recent judgments of the High Courts have shed some light on this issue, tackling important questions such as: (1) Is post-filed data generally accepted at the IPO; and (2) under what circumstances can post-filed data be considered admissible or, conversely, inadmissible.

Post-filed data:

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“.

Admissibility of post-filed 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 Ab & Anr. vs Alkem Laboratories Limited on 2 November, 2020,(02.11.2020 – DELHC) : MANU/DE/1939/2020 the Court’s decision offers some guidance on when post-filed data cannot be taken on record:

Post 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 “was directed to that which ‘would inherently flow’ from what was originally disclosed [with emphasis]

Thus in this case following the precedent of Generics (UK) Ltd. v. Yeda Research & Development Co. Ltd., (2017) EWHC 2629 (Pat) (U.K.), relied upon by the Defendants to challenge the validity of the patent-in-suit for lack of inventive step, the Court observed prima facie that post priority date evidence furnished by way of an affidavit by plaintiffs to demonstrate technical advance can only be taken into account to confirm the existence of technical effect disclosed in the specification of the patent that is capable of being understood by a skilled person having common general knowledge. The Court held that this evidence cannot be relied upon to establish its effect for the first time. The Single Judge observed that the plaintiffs were unable to demonstrate, at least at the interim stage, the existence of such technical effect in the specification. The Court noted that the plaintiffs’ argument that the examiner should have been conscious of the inventive step objection or that evidence of technical advance could be placed before the Court even at this juncture fails to take into account the plain language of Section 64(1)(f) read with Section 2(1)(ja) of the Patents Act, 1970 (India). The Court observed that the Defendants are entitled to submit, in support of their challenge, that there is no demonstrable technical advance as on the date of priority of the patent-in-suit. This order is currently under challenge in appeal and pending adjudication before the Division Bench (2 Judges) of the Hon’ble Delhi High Court.

In La Renon Health Care Pvt. Ltd Vs Union of India and Ors; W.P. No. 1219 of 2014 and M.P. No. 1 of 2014 (MANU/TN/0615/2019), the Hon’ble High Court of Madras observed as follows on the importance of evidence.

  1. The petitioner cannot shift the burden either on the 4th respondent or on the 3rd respondent Appellate Board. The Petitioner had an opportunity to let in evidence of an expert to substantiate the grounds for revocation. However, the petitioner failed to do so. 
  1. The petitioner has not produced any evidence of an expert before the third respondent Appellate Board to substantiate its plea that the invention is a mere “admixture” or that the Patent was liable to be revoked on the grounds stated in the petition filed by it. 
  1. To appreciate the evidence filed in support of the petition for revocation of patent, the petitioner should have played a proactive role by either producing an expert or an expert’s affidavit and if necessary such expert could have been subjected to cross examination. 

In a recent decision the Hon’ble Culcutta High Court further highlighted the importance of evidence during prosecution of a patent application ‘OYSTER POINT PHARMA INC V. THE CONTROLLER OF PATENTS AND DESIGNS’, AID No. 10 of 2022 (MANU/WB/1544/2023). The invention related to “Stereospecific synthesis of (R)-5(E)-2-pyrrolidin-3-ylvinyl) pyrimidine, its salt forms, and novel polymorphic forms of these salts”. The application rejected under sections 2(1)(ja) and 3(d) of the Patents Act, citing 3 prior art documents.

Hon’ble Kolkata High Court observed that, “a new form of a known substance can only be considered patentable provided the same demonstrates enhanced efficacy. However, it is not possible to determine the efficacy of a substance without considering the results of experiments conducted and the comparative studies made before arriving at any conclusion by a skilled person. The details of the experiments conducted, comparative studies made and their conclusive results had been discussed in Appendix A, B and C in support of the claimed invention and the same ought to have been considered before passing of the order. There is no substance in the contention that the additional documents could not be considered after filing of the patent application at a later stage. No specific time bar has been provided in the Act which prevents an applicant from filing additional documents after the filing of patent claim.

In fact, Appendix A, B, C contained data to show that the claimed compound possessed efficacy. The Controller has without assigning any reasons rejected Appendix C and has failed to deal with Appendix A and Appendix B.”

The Controller should have considered the details of the experiments conducted, comparative studies made and their conclusive results to determine efficacy. The court clarified that there is no specific time bar in the Act that prevents an applicant from filing additional documents after the filing of a patent claim and therefore set aside the order and remanded the matter back to the respondent to consider afresh.

As far as Indian Patents Act is concerned Section 79 is relevant. It specifies, how Evidence is to be given and delineates powers of  the Controller: Subject to any rules made in this behalf, in any proceeding under this Act before the Controller, evidence shall be given by affidavit in the absence of directions by the Controller to the contrary, but in any case in which the Controller thinks it right so to do, he may take oral evidence in lieu of, or in addition to, evidence by an affidavit, or may allow any party to be cross-examined on the contents of his affidavit.

Sections 101 and 102 of the Indian Evidence Act, 1872, show that the burden of proof in any proceedings lies on that person who will fail if no evidence at all were given. Hence, in any patent opposition proceeding, including a pre grant opposition, the burden of proof in establishing each and every ground would lie on the opponent. It is in keeping with this principle that Rule 55 (1) of the Patent Rules, 2003, requires the opponent to file its evidence in support of the representation. It is clear from Section 79 of the Patents Act 1970, that the evidence has to be given by way of affidavit. Consequently, of no evidence in the form of an Affidavit is filed in an Opposition, the Opponent fails in discharging its burden and the opposition is liable to be dismissed on this ground alone.

In Strix Limited Vs Maharaja Appliances Limited (MIPR 2010 (1) 0181, the Hon’ble High Court of Delhi observed as follows:

“It was contended by learned Counsel for the Defendant that at an interlocutory stage, the Defendant should be held to have discharged its burden of raising a “credible challenge” to the validity of the Plaintiff’s patent by merely pointing out the existence of a European Patent. This Court is unable to agree. In order to raise a credible challenge to the validity of a patent, even at an interlocutory stage, the Defendant will have to place on record some acceptable scientific material, supported or explained by the evidence of an expert that the Plaintiff’s patent is prima facie vulnerable to revocation(Para 22).

The Controller under the Patents Act is a quasi-judicial authority having the powers of a Civil Court. Indian IPO Examiners and Controllers typically consider whether there is a link between the data disclosed in the as-filed application and the post-filing data when determining whether to accept post-filing data. A Controller will likely refuse to examine the post-filed data if the data is largely divergent from the disclosure made in the specification, or there exists a gap or a lack of a link between the data and the disclosure in the specification. On the other hand, if the data is to demonstrate the accuracy of the disclosure made in the specification, and thereby establish that the results indicated therein were unexpected and not contemplated in the prior art references cited by the patent office, it is possible to persuade the patent office to admit the data.

From the above, 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-filed efficacy data should be within the scope of the originally-filed specification. Indeed, in an early 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.

In recent judgements at the IPAB and the Delhi High Court both forums unequivocally permit reliance on post-filed 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-filed data is 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 the time of filing the application, 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-filed data.

Evidence during Pre-grant Opposition Proceeding:

Rule 55 of the Patents Rules 2003 stipulates that representation for a pre-grant opposition needs to include a statement of case and evidence, if any.

On consideration of the representation, if the Controller is of the opinion that a patent application ought to be refused or amended, the Controller will send a notice to the applicant accordingly. On receipt of the notice, the applicant is required to submit a copy of its statement and evidence in support of its application if the applicant so desires and also serve a copy of the same to the opponent.

Evidence during Post-grant Opposition Proceeding:

In India, a granted patent can be invalidated (opposed) by way of two kinds of proceedings:

  1. Post-grant opposition under Section 25(2) before the Indian Patent Office to be filed   by a ‘person interested’.
  2. Revocation petition filed under Section 64 before the concerned High Court following the jurisdiction by a person interested or on a counter-claim in a suit for infringement of the patent by the respective High Court.

In a recent decision in the case of Akebia Therapeutics Inc. vs. Controller General of Patents, Design, Trademark and Geographical Indications, & Ors. W.P. (C) IPD 32/2023, CM 92/2023 and CM 93/2023 (MANU/DE/5210/2023), the Delhi High Court discussed the pleadings and relevant procedure of post-grant opposition in India. The Hon’ble Court evaluated the proper way to file reply evidence and the permissible scope of the corresponding pleadings.

Facts of the case:

The Opponent filed a post-grant opposition and documents on September 24, 2018

The Patentee filed its Reply statement on January 15, 2019

The Opponent filed a rejoinder and Expert Affidavit on February 14, 2019

The Patentee filed a Miscellaneous Petition 1 on April 23, 2019, objecting to the Affidavit of the Opponent and filed a Miscellaneous Petition 2 on February 07, 2020, seeking to file further evidence.

The relevant rules of the pleadings filed in a post-grant opposition are as follows:

  1. Filing of written statement of opposition and evidence.— The opponent shall send a written statementin duplicate setting out the nature of the opponent’s interest, the facts upon which he bases his case and relief which he seeks and evidence, if any, along with notice of opposition and shall deliver to the patentee a copy of the statement and the evidence, if any.
  2. Filing of reply statement and evidence.—

(1) If the patentee desires to contest the opposition, he shall leave at the appropriate office a reply statement setting out fully the grounds upon which the opposition is contested and evidence, if any, in support of his case within a period of two months from the date of receipt of the copy of the written statement and Opponent’s evidence, if any by him under rule 57 and deliver to the opponent a copy thereof.

(2) If the patentee does not desire to contest or leave his reply and evidence within the period as specified in sub-rule (1), the patent shall be deemed to have been revoked.

  1. Filing of reply evidence by opponent.—The opponent may, within one month from the date of delivery to him of a copy or the patentee’s reply statement and evidence under rule 58, leave at the appropriate office evidence in reply strictly confined to matters in the patentee’s evidence and shall deliver to the patentee a copy of such evidence.
  2. Further evidence to be left with the leave of the Controller.—No further evidence shall be delivered by either party except with the leave or directions of the Controller: Provided that such leave or direction is prayed before the Controller has fixed the hearing under rule 62.
  3. Copies of documents to be supplied.—

(1) Copies of all documents referred to in the notice of opposition or in any statement or evidence filed in connection with the opposition and authenticated to the satisfaction of the Controller, shall be simultaneously furnished in duplicate unless the Controller otherwise directs.

(2) Where a specification or other document in a language other than English is referred to in the notice, statement or evidence, an attested translation thereof, in duplicate, in English shall be furnished along with such notice, statement or evidence, as the case may be.

Important takeaways from the Court’s analysis based on the facts of the case:

  1. Rule 57 stipulates filingof a post-grant opposition “and evidence”. Section 79 of the Indian Patents Act stipulates the provision for filing “evidence”. It requires that evidence is to be given by affidavit. Thus, documents un-accompanied by such affidavit would not constitute “evidence” under Rule 57.

The Court referred to decisions such as Taylor v. Taylor ((1875) 1 Ch D 426), State of U.P. v. Singhara Singh (AIR 1964 SC 358) to reiterate that where the law requires an act to be done in a particular manner, the act has to be done in that manner alone, or not done at all.

The Court noted that Rule 61 also differentiates between the evidence filed under Rules 57 to 60, and the documents referred to in the evidence.

  1. Rule 58 requires filing of a “reply statement” of the Patentee accompanied with “evidence, if any, in support of his case”.
  2. Rule 59 requires the Opponent to file “further evidence” that is “strictly confined to matters in the patentee’s evidence”.The Court observed that Rule 59 is notto be read as filing of a rejoinder.

In the Akebia case, the Hon’ble Court noted that the Opponent did not file any evidence with the opposition document and thereafter, the Patentee did not file any evidence with their Reply statement. Accordingly, it was contented by the Petitioners that the Opponent could not have filed Evidence (Expert Affidavit) in response to the Reply statement. Importantly, the Opponent did file an Expert Affidavit at the stage of Reply Evidence (Rule 59) along with a rejoinder to the Reply of the Patentee and thereafter, the Patentee filed a petition requesting leave to file additional evidence under Rule 60.

The Opposition Board constituted in Post-grant oppositions by the Controller, comprising of 3 members considers the opposition documents including written stamen & evidence and the Reply statement & evidence filed by Applicant. In the Akebia case Hon’ble Court quashed the recommendations of the Opposition Board on the observation that the remaining documents (evidence) prescribed to be considered are to be filed. Conclusively, the Court ordered that the Expert Affidavit and the opposition documents were to be considered by the Opposition Board along with the Reply statement of the Patentee. Further, the Patentee has been given an opportunity to file further evidence (also to be considered by the Board). Thus High Courts involvement in patent disputes has led to much needed clarity in rules and procedure.

In the Pharmacyclics LLC vs. Union of India [W.P.(C) 12105/2019 decided on 20th November, 2019] AND also in  Novo Nordisk vs. Union of India & Ors., decided by Delhi High Court on 5th July, 2022 cases the Honb’le Delhi High Court has reiterated the principles that have to be followed by the Opposition Board, Patent Office, and parties in opposition proceedings based on principles laid down. While doing so, the Court emphasized the need to expedite post-grant opposition proceedings, and the need for the patent office to abide by the provisions of the Patents Act and Rules.

Some important principles laid down by the Court are as follows:

  1. Post-Grant opposition proceedings are adversarial proceedings, which require the patent office to strictly comply with principles of natural justice with respect to consideration of evidence, sharing of reports, and hearings.
  2. Parties have to submit evidence within timelines provided under the Patent Rules, and cannot delay proceedings or seek adjournments based on additional evidence.
  3. The Opposition Board and the Patent Office have to strictly follow the timelines, and have to stick to the evidence filed by the parties while arriving at their decisions/recommendations in compliance with applicable rules.
  4. The recommendations of the Opposition Board are not only persuasive, but crucial in post-grant opposition proceedings. They must be shared with the parties before a hearing is scheduled. The names of members of the Opposition Board must be provided on the cover page and signature pages clearly.
  5. The Opposition Board has to give its recommendations based only on the evidence filed by the parties, and parties can file additional evidence only with the leave of the Controller hearing the proceeding. However, this is not applicable to publications, which may be filed five (5) days before the date of hearing.
  6. The Patent Office has to give a comprehensive decision based on pleadings/evidence of parties, applications filed by the parties, and recommendations of the Opposition Board. The decision may be to grant the patent, amend the patent, or revoke the patent.
  7. The recommendations of the Opposition Board, and the decision of the Controller of Patents must only be based on grounds raised by the parties and evidence submitted by them.

Para 31 of the case, which crystallizes evidence related principles reads as follows:

“i. The Opponent and the Patentee have adequate freedom to file their initial pleadings and evidence by relying upon all the documents and expert testimonies that they wish to;

  1. The Opponent’s rejoinder in Rule 59 ought to be strictly confined to the Patentee’s evidence;

iii. Once the Opposition Board is constituted and the material is transmitted to the Board, further evidence is not permissible;

  1. Under Rule 60, if any further evidence comes to light which either party wishes to rely upon, the same can only be done prior to the issuance of notice of hearing, with the leave of the Controller;
  2. v) Under Rule 62(4), only publicly available documents i.e. publications, can be considered provided they are served to the opposing party, five days prior to the hearing and the date/time of the publications as also the relevant portions are highlighted, so that the opposite side can deal with the same at the time of hearing. Any document the authenticity of which is in doubt would not be

Technical Affidavit to be furnished by a technical person in that particular field. It is a good practice to hire independent experts to give unbiased opinions. The opinion must be restricted to technical aspects and not on the legal aspects of the application or cited references therein.  A patent agent can furnish an affidavit in regard to his/her opinion on different citations and distinguishing features of the invention. Patent agent can also furnish his opinion on legal aspects such as novelty, inventive step as well as objections pertaining to the non-patentability.

Further question arises whether, if a hearing is adjourned, further evidence ought to be permitted or not prior to the next hearing. Clearly from the scheme of the Act, filing of further evidence would not be permissible after the first notice of hearing is issued. Thus, in terms of Rule 60, the hearing as contemplated in the said Rule would be the first notice of hearing. Such an interpretation would ensure that parties do not unduly delay the hearing of oppositions by seeking adjournments and utilising the adjourned period to dig up more evidence, especially as such evidence would in any case have not been considered by the Opposition Board. The filing of further evidence prior to the hearing or reliance on publications under Rule 62(4) would not ordinarily permit an adjournment of the hearing. In the Controller’s discretion, within a reasonable time, parties may be permitted to support their oral arguments with written submissions which would again be transmitted simultaneously and would not again be treated as documents to which responses can be filed.


While drafting patents, we as patent attorneys generally focus on the claims, the detailed description and the background but the aspect of evidence that is needed is often neglected. The lack of evidence or the variance in evidence from the detailed description and the claims generally bothers us during prosecution. Finally, it is the evidence that is filed either during filing of the application or after filing during prosecution convinces Examiners to grant a patent to an invention. If we miss filing evidence at the drafting stage or the inventor does not provide such evidence, as patent attorneys, we should not rest until the inventor provides some form of evidence to support the findings in the invention.