Delhi High Court rules on process for amending patent claims during PCT application entry into India

On 23 February 2024 the Delhi High Court issued a ruling in Mitsui Chemicals v Controller of Patents, in which it adjudicated on issues concerning the:

• treatment of claims during a PCT application’s national phase entry into India;
• patentability of a method of agriculture under Section 3(h) of the Patents Act 1970; and
• procedure for claim amendments under Section 59 of the Patents Act.

Section 3(h) of the Patents Act bars the patenting of inventions relating to a method of agriculture or horticulture. Further, any amendments in the specification or patent claims are governed by the provisions of Sections 57 and 59 (CA (COMM IPD-PAT) 196/2022). 

Case background

Mitsui filed a patent application with national phase claims directed towards a “method of preventing plant disease and insect damage” (3877/DELNP/2009). The claims were subsequently amended to “an insecticidal composition” to overcome an objection raised by the Indian Patent Office (IPO) under Section 3(h). However, the IPO still refused the patent application under Section 59(1) on the basis that the amended claims did not fall within the scope of the original claims directed towards a method of treatment of plants. The objection on the national phase claims under Section 3(h) was also maintained. 

Mitsui filed an appeal against this order at the Delhi High Court. It contended that the IPO had erred in its assessment of the original claims as ‘method claims’ in the national application. and argued that since no such request for amending the claims was made while filing the national phase application in India, the original PCT claims outlining an insecticidal composition should have been considered when evaluating the scope of the amended claims (and not the pre-amended claims/national phase claims that were directed towards a “method of preventing plant disease and insect damage”).

Delhi High Court decision

The court relied on the provisions of Section 138(4) of the Patents Act, which states that for a PCT application designating India, the claims as filed in the international application are inherently considered to be part of the complete specification. The court further emphasised the provisions of Section 138(6), which permits applicants to incorporate amendments that are proposed before the international searching or preliminary examination authorities into their national phase application in India – should they choose to do so. 

With no evidence of any amendment request under Form 13, according to the court, the IPO had mistakenly referenced the national phase claims directing to a “method of preventing plant disease and insect damage”, instead of the original PCT claims. 

It was further clarified that while a 2016 amendment to Rule 20 of the Patent Rules allows deletion of claims without filing an amendment application, this change did not impact the application in question as it was filed in 2009 – prior to the cut-off date. This ruling emphasises that being unable to reintroduce deleted PCT claims during the prosecution stage of national phase applications was due to misunderstanding the claim amendments procedure. 

The court also stressed that when rejecting an application under Section 3(h), a more nuanced and detailed analysis is required to determine whether the invention genuinely constitutes a method of agriculture, or embodies a technical solution to agricultural challenges that does not fall within the scope of Section 3(h). This echoed a Calcutta High Court ruling in Decco Worldwide Post Harvest Holdings & Anr v The Controller of Patents and Designs & Anr (CA (COMM IPD-PAT) 196/2022). 

Accordingly, the court concluded that the impugned order was unsustainable and set it aside, remanding the matter back to the IPO for de novo consideration. 

Key takeaways

This judgment underscores the importance of procedural adherence in the evaluation of patent claim amendments during prosecution, as well as reasoned orders by the IPO. It also establishes that methods of plant treatment are distinct from traditional methods of agriculture and may not be censured by Section 3(h) of the Patents Act.