Delhi High Court holds that known substances must be clearly identified

Interpreting Section 3(d) of the Patents Act in the context of pharmaceutical patent applications, the Delhi High Court has held that the Indian Patent Office (IPO) must clearly and unequivocally identify “known” substances (CA (COMM IPD-PAT) 6/2021). The ruling responded to an appeal instituted by DS Biopharma (appellant), which challenged an order passed by the IPO. After hearing the parties at length, the court allowed the appeal and remanded the matter to the IPO for reconsideration on merits.

The appellant contended that at the stage of oral hearing proceedings, the only new objection raised pertained to Section 3(d) of the act, as the remaining objections in response to the first office action had been addressed to the IPO’s satisfaction. Further, the IPO had gravely erred by failing to specify which part of Section 3(d) applied to the claimed subject matter. Relying on a previous judgment (Fresenius Kabi Oncology Limited v Glaxo Group Limited & Anr, 2013 SCC Online IPAB; ORA/22/2011/PT/KOL) passed by the former Appellate Board, it was asserted that, at the very least, the IPO should have specifically addressed three questions.

  • What is the specific known substance in question?
  • How – and why – are the claimed molecules or substances a derivative or otherwise a new form of a known substance?
  • What is the basis of the assertion that the alleged ‘known’ substance and the claimed molecule or substance have the same ‘known’ efficacy?

Since the IPO failed to identify any of these factors, it denied the appellant an opportunity to clearly respond to its objection and severely hampered DS Biopharma’s rights to defend the patent application. It was argued that the IPO’s omission meant that the appellant was under no legal obligation to demonstrate efficacy of the claimed compounds under Section 3(d) of the act.

In response to the appellant’s assertions, the IPO contended that the objection under Section 3(d) had been specified in the hearing notice and the cited prior art was in the appellant’s possession. Since the appellant failed to provide efficacy data, the patent had been rightly rejected.

The court carried out a detailed analysis and opined that the known substances identified in the final decision under Section 3(d) could have been contained in the hearing notice – so  the appellant could have responded in the first instance. In such a case, the appellant may have been in a position to establish enhanced therapeutic efficacy of the claimed compounds.

While concurring with the appellant, the court held that although the Fresenius Kabi judgment was also in the context of Section 3(d)’s applicability in a revocation action, its observations were equally relevant in this case. Since Section 3(d) precludes patentability of a “new form” of a known substance, the basic prerequisite is the known substance’s identification – the burden of deduction cannot be placed on the applicant. The known substance could either be a single substance, or several compounds derived from a Markush formula. For the purposes of a Section 3(d) objection, it is imperative to identify at least one specific known substance, along with the manner in which the claimed compounds are ‘new forms’. Mere mention of an objection under Section 3(d), without mentioning the manner in which said objection applies, was not considered sustainable.

The judgment assumes tremendous significance in the backdrop of the prevailing practice at the IPO, wherein an objection under Section 3(d) invariably finds mention in pharma patent applications without concrete reasoning or evidence as to how the section applies. In certain cases, it can become extremely difficult to ascertain the applicability of the operative portion of said section. This decision clearly spells out the statutory duty of the IPO and will hopefully improve extant practice.


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