By Jigyasa Pareek

Under Indian patent law, a post-grant opposition can be filed under Section 25(2) of the Patents Act, 1970, within one year from the grant of a patent. This mechanism enables interested parties to challenge the validity of a granted patent before the Controller on grounds such as lack of novelty, lack of inventive step, insufficiency of disclosure, etc.

To ensure speedy disposal, the opposition process is tightly structured by Rules 55A-62 of the Patents Rules, 2003. Each stage (notice of opposition and evidence, reply statement and evidence, rejoinder, further evidence, etc.) is bound by time limits. The Opposition Board examines the pleadings and evidence, and its recommendation (OBR) assists the Controller at the hearing stage.

Evidence in opposition proceedings is ordinarily filed by way of affidavit, as provided under Section 79 of the Patents Act. The Controller also has discretion under this provision to allow oral evidence or permit any party to be cross-examined on the contents of their affidavit.

Any request to file further evidence requires leave or direction of the Controller, as provided under Rule 60 of the Patents Rules. Such requests, along with others including objecting to the filing of the further evidence, seeking leave to file rebuttal evidence, cross-examination, are generally moved through Miscellaneous Petitions under Rule 128 of the Patents Rules.

Under these procedural rules lay the principles of natural justice. Courts have consistently emphasized that opposition proceedings must be conducted fairly: no party’s evidence should be accepted without affording the other side a fair opportunity to respond. But fairness is reciprocal: it does not extend to granting unlimited opportunities or permitting undue delays.

This balance came to the forefront in Novartis AG vs Controller of Patents & Designs [W.P.(C)-IPD 50/2025, 51/2025, 52/2025; 2025:DHC:8211], where the Delhi High Court considered whether a patentee could demand cross-examination at a belated stage in post-grant opposition proceedings.

Novartis was granted Indian Patent IN’518 on 14 December 2022. Three post-grant oppositions were filed. Respondent No. 2/Opponent (IPA) placed further evidence on record under Rule 60; Novartis contested the admissibility of the further evidence and sought, alternatively, leave to file rebuttal evidence. By order dated March 17, 2025, the Controller admitted the further evidence but denied Novartis leave to file rebuttal. On the same date, the Opposition Board submitted its recommendation, proposing revocation of the patent.

Aggrieved, Novartis filed writ petitions before the Delhi High Court [earlier writs: W.P.(C)-IPD 18/2025, 19/2025 and 20/2025] asking the Court to set aside the order and quash the OBR, pleading that denial of an opportunity to file rebuttal evidence was violative of the principles of natural justice. The Court upheld the admission of further evidence but also granted Novartis leave to file rebuttal evidence, set aside the OBR, and directed a time-bound schedule for filing rebuttal, a fresh OBR, and a final hearing to ensure an expeditious disposal. The Court also acceded to Novartis’s request for the appointment of a new Controller to adjudicate the opposition proceedings.

In compliance, Novartis filed rebuttal evidence in mid-June 2025. The Opposition Board then submitted a fresh recommendation on July 14, 2025, again recommending revocation. The Controller communicated the OBR to the parties on July 15, 2025, and issued a hearing notice fixing the hearing for August 19, 2025. Interestingly, on July 14, 2025, at 21:14, Novartis filed a Miscellaneous Petition seeking cross-examination of the Opponent’s experts; that petition was served on the Opponent on July 15, 2025. At the hearing on August 19, 2025, the Controller recorded that she would first hear the Opponents on merit and thereafter decide the Miscellaneous Petition. The matter was posted for further hearing on August 20, 2025. However, Novartis absented itself from the hearing of August 20, 2025. The Controller proceeded to hear the Opponents, closed arguments, and reserved the final order. Novartis thereafter approached the Delhi High Court alleging that denial of cross-examination violated the principles of natural justice.

Novartis relied on the Division Bench’s decision in Onyx Therapeutics vs Union of India [2019 SCC OnLine Del 11881] to argue that cross-examination under Section 79 is not a matter of discretion but a matter of right. Novartis further argued that the request for cross-examination was not belated because the necessity of cross-examining was realized only after consultations with their own experts and after considering availability of their witnesses for cross-examination. Novartis also proposed that cross-examination could be completed in a short time frame and the Opposition Board could reconsider its recommendation thereafter.

The Respondents, on the other hand, characterised the filing of the Miscellaneous Petition as a dilatory tactic to protract the opposition proceedings. They pointed out that the expert affidavits had been on record since July 2024, yet Novartis chose not to seek cross-examination earlier, not even when it had moved the earlier writ petitions in April 2025. They argued that Novartis had already availed the liberty to file rebuttal evidence and having taken that opportunity, claiming cross-examination as an additional right months later was nothing but an abuse of law. They stressed that it was a clear case of implied waiver of the right to cross-examine. The Respondents also argued that the Miscellaneous Petition was filed at 21:14on the very day the fresh OBR was due, and therefore it was a clear attempt to stall the proceedings until the patent’s expiry in November 2026.

The Delhi High Court acknowledged that Section 79 empowers the Controller to permit cross-examination and that Onyx Therapeutics underscores its significance. But the Court was equally clear that the right to cross-examine is not absolute and must be exercised diligently and at the earliest opportunity after the cause of action has arisen. The Court, in its judgment, clarified that the principles of natural justice cannot be wielded “as a sword of convenience” at the patentee’s whim.

The Court distinguished Onyx Therapeutics from the instant case, pointing out that in Onyx the patentee had preserved the right to cross-examine at each stage (by making a request to cross-examine in the reply statement, and when that was denied, by filing a formal petition). The Court noted that, Novartis, on the other hand, consciously elected to rebut the Opponent’s expert affidavits by filing rebuttal affidavits and made no request for cross-examination. On this basis, the Court held that Onyx could not be read as requiring the Controller to entertain such a belated request.

The Court stressed that “right (to cross-examine) is to be exercised not later than the stage when the evidence is admitted by the Controller. This right does not remain available to the party for all times to come until the issuance of notice of hearing”.The patentee cannot keep the right in reserve and invoke it at a later stage; the appropriate stage for such request is at the earliest opportunity, after service of the expert’s evidence. The Court clarified that the right to cross-examine is to be exercised by the patentee at the reply stage under Rule 58 and before it elects to file rebuttal evidence.

The Court noted that Novartis had a whole year to seek cross-examination (the Opponent’s expert affidavits were on record from July 2024) but had not done so. The Court specifically held that “by consciously refraining from making any request until after the High Court, by order dated 21.04.2025, had finally ruled on the admissibility of the expert evidence, the Petitioner unequivocally elected to forgo the right to cross-examine the Respondent No.2’s Experts. Having allowed the earlier writ petitions to attain finality without raising this plea, the Petitioner is now estopped from asserting the right belatedly and the doctrine of waiver operates to bar such an afterthought.”.

The Court emphasised that natural justice cannot be weaponised to obstruct proceedings. The Court was particularly critical of Novartis’s submission that the Opposition Board should be directed to give yet another recommendation after cross-examination, describing this as a “nonchalant” and “dismissive outlook” towards the time and effort the Board.

The Court also reprimanded Novartis’s conduct in abstaining from the hearing before the Controller. The Court held that a party that knowingly chooses not to appear cannot later claim violation of natural justice. By consciously electing not to appear, Novartis was deemed to have abandoned its Miscellaneous petition.

In conclusion, the Court dismissed the petitions, holding that Novartis’ request for cross-examination was barred by waiver and estoppel.