Why priority date matters: Madras High Court emphasises importance of reasoned orders

Introduction

The Madras High Court last year revisited a fundamental but often overlooked question in patent practice, namely how and when a claim is entitled to draw priority from a provisional specification. The High Court set aside the order of the Deputy Controller of Patents and Designs (‘Respondent 1’), who refused Indian Patent Application No. 4135/CHEN/2014 (‘Application’) filed by Rallis India Limited (‘Appellant’). In examining the manner in which the Indian Patent Office (‘IPO’) treated a cited prior art, the High Court underscored the necessity of reasoned and complete adjudication of all material contentions. The judgment offers timely guidance on the application of Section 11 of the Patents Act, 1970 (‘Act’), particularly where entitlement to priority forms the basis of a refusal. This article analyses the decision and its implications for patent prosecution and opposition practice.

Facts of the case

The Appellant filed the Application titled ‘Stable Herbicidal Composition comprising Pendimethalin and Metribuzin’ before the IPO on 25 August 2014. Pursuant to a request for examination, the IPO issued a First Examination Report (‘FER’) on 22 July 2019. In the FER, objections were raised on the grounds of lack of novelty, lack of inventive step, non-patentability under Sections 3(d) and 3(e) of the Act, among other objections.

A first pre-grant opposition against the Application was filed by Haryana Pesticide Manufactures Association (‘Respondent 2’) on 10 September 2019 under Sections 25(1)(b) to 25(1)(f) of the Act. Among other grounds, Respondent 2 asserted prior claiming under Section 25(1)(c) of the Act in view of IN 2243/MUM/2014, which was cited as D7.

Subsequently, a second pre-grant opposition was filed by Chimanbhai Chauhan (‘Respondent 3’) on 5 December 2022 under Sections 25(1)(b) to 25(1)(f) of the Act. Respondent 3 also relied on Indian Application IN 2243/MUM/2014, cited as D1, in support of the ground of prior claiming.

Upon completion of pleadings, hearings, and written submissions in the pre-grant opposition proceedings, Respondent 1 issued an order dated 5 March 2024 refusing the Application. The refusal was based on prior claiming in view of IN 2243/MUM/2014 (referred to as D3 in the impugned order), lack of inventive step in view of prior art documents related to the combinations of pendimethalin and metribuzin cited as D1 and D2, non-patentability under Section 3(e) of the Act, and lack of sufficiency of disclosure under Section 10(4) of the Act.

Claim 1 of the Application, which was rejected, recited the following:

‘A Stable Herbicidal emulsifiable concentrate (EC) pre-mix composition comprising: 
 

1. active agents consisting of Pendimethalin Technical in the range from 25 to 52 w/w% and Metribuzin Technical in the range from 6 to 12 w/w%; 
    
2. Solvent in the range from 24 to 55w/w%; 
    
3. Co-solvent in the range of 4 to 6 w/w%; 
    
4. Non-ionic surfactant in the range of 3 to 5w/w%; and 
    
5. Ionic surfactant in the range of 3 to 5w/w%.’
    

The Appeal 

Aggrieved by the refusal order, the Appellant challenged the decision before the High Court and advanced several contentions against the impugned order. 

At the outset, the Appellant contended the rejection of the Application on the ground of prior claiming in view of Indian Patent Application No. 2243/MUM/2014 (‘D3’) was untenable, as D3 did not qualify as a valid prior art in respect of the claimed emulsifiable concentrate (EC) formulation. The Appellant submitted that although the provisional specification of D3 was filed on 9 July 2014, it did not disclose an EC formulation. On the contrary, the provisional specification of D3 was limited to a suspo-emulsion (SE) formulation and expressly asserted the superiority of SE formulation over EC formulation. According to the Appellant, this explanation was specifically provided before the IPO in the reply statement and in the written submissions filed in the pre-grant opposition proceedings initiated by Respondent 3. However, no finding was recorded on this issue in the impugned order.

The Appellant further contended that D3 stood deemed to have been revoked under Rule 58(2) of the Patents Rules, 2003 (‘Rules’), on account of the failure of the patentee of D3 to file a reply statement within the prescribed time in response to a post-grant opposition filed by the Appellant. It was submitted that this objection was also brought to the notice of the IPO, but was not addressed and examined in the impugned order.

In addition, the Appellant sought to distinguish the claimed EC composition of the Application from the formulation of D3 on the basis of excipients employed. It was argued that the formulation of D3 relied on excipients that resulted in the presence of insoluble solid particles, whereas the claimed EC composition of the Application did not comprise such insoluble agents.

Regarding the objection on lack of inventive step in view of prior art documents cited as D1 and D2, the Appellant contended that Respondent 1 failed to appreciate that these documents neither taught nor suggested the specific concentration ranges ofpendimethalin technical and metribuzin technical claimed in the Application, nor did they disclose or motivate an EC composition.

The Appellant also challenged the rejection of the claims under Section 3(e) of the Act. In this regard, reliance was placed on the experimental data set out in Table 1 of the as-filed specification of the Application, which according to the Appellant, demonstrated a synergistic effect arising from the combination of the active agents recited in the claimed EC composition. 

Finally, the Appellant submitted that the as-filed specification of the Application sufficiently discloses the claimed EC composition, including the method of preparation and the best mode of working the invention. 

Contentions presented on behalf of the respondents

Respondent 1 opposed the appeal and sought affirmation of the impugned order. It was contended that the priority date of D3 was 9 July 2014, being the date of filing of its provisional application, which preceded the priority of the Application filed on 25 August 2014. According to Respondent 1, D3 disclosed pendimethalin and metribuzin in concentration ranges that overlapped with the ranges claimed in the Application, and the marginal difference of 2% in the upper limits did not amount to any technical advancement, being statistically and practically negligible.

Respondent 1 further submitted that the prior art documents cited as D1 and D2 disclosed combinations of pendimethalin and metribuzin with established herbicidal efficacy. It was argued that the claimed EC composition of the Application was a mere aggregation of known components, without any demonstrated synergistic effect. In this regard, it was also contended that the as filed specification of the Application failed to provide reproducible experimental examples or a clear explanation of the role played by excipients in achieving any enhanced effect.

Respondent 2 similarly contended that the claimed subject matter of the Application was anticipated by D3. It was submitted that D3 disclosed compositions comprising pendimethalin and metribuzin in multiple formulation forms including suspension concentrate (SC), emulsifiable concentrate (EC), zeon concentrate (ZC), and oil dispersion (OD). Particular reliance was placed on Example 3 of D3, which according to Respondent 2, disclosed inactive components corresponding to those recited in claims of the Application.

Respondent 3 also opposed the appeal and asserted that the provisional specification of D3 disclosed an EC formulation along with specific surfactants and solvents. On this basis, Respondent 3 contended that D3 was entitled to claim priority from its provisional filing date and constituted a valid prior art against the Application

The High Court's analysis

The High Court first examined the validity of treating D3 as prior art. In this context, the High Court reviewed Sections 11(1), 11(2), and 11(6) of the Act, which govern the determination of priority dates of patent claims. The High Court noted that Section 11(2) of the Act mandates that where a complete specification is filed pursuant to a provisional specification, the priority date of a claim shall be the date of filing of the provisional specification, provided the claim is fairly based on the matter disclosed in the provisional specification.

Against this statutory backdrop, the High Court observed that the Appellant specifically raised the contention, during the pre-grant opposition proceedings, that the priority date of D3 could not be reckoned from the filing of its provisional specification insofar as the claimed EC formulation was concerned. Although this contention was noticed in the impugned order, the High Court found that no finding had been recorded on the issue.

The High Court thereafter examined the disclosure contained in the provisional specification of D3 to assess the merit of the Appellant’s contention. On a review of the provisional specification, the High Court found that it disclosed only an SE formulation, and that any reference to the EC formulation was limited to statements highlighting the inferior efficacy of EC formulation when compared to SE formulation. The High Court further compared this disclosure with the granted claims 1 and 17 of D3, which extended to EC formulation. In light of this comparison, the High Court held that the Appellant’s objection could not be rejected outright and warranted careful examination and a definitive finding.

The High Court noted that despite placing significant reliance on D3 in the impugned order, Respondent 1 failed to record any finding whether the EC related claims of D3 were fairly based on its provisional application. Given the centrality of D3 to the refusal and to the arguments advanced in the pre‑grant opposition proceedings, the High Court held that the omission to consider and decide this issue vitiated the impugned order.

The High Court then turned to the assessment of the inventive step. The Court observed that Respondents 2 and 3 relied on multiple prior art documents during the pre-grant opposition proceedings. However, the impugned order discussed only two such documents, cited as D1 and D2. Upon examining D1 and D2, the High Court found prima facie merit in the Appellant’s contention that these documents did not disclose an EC formulation, thereby warranting closer scrutiny.

The High Court further found that the impugned order suffered from a broader failure to record findings on several material issues. Apart from the absence of a finding on whether D3 qualified as a valid prior art, the High Court noted that several prior art documents relied upon by Respondents 2 and 3 had not been considered at all. In addition, the affidavits filed by Mr. G.N. Kendapa and Mr. Vairamani Ramanathan were neither discussed nor assessed, and no finding was recorded as to whether they were to be relied upon or disregarded.

In view of these deficiencies, the High Court considered it unnecessary to adjudicate upon the remaining objections, including the Appellant’s contention regarding the deemed revocation of D3. Accordingly, the High Court set aside the impugned order dated 5 March 2024 and remanded the matter for fresh consideration. The High Court directed that the application be reconsidered by a different Controller, with proper findings to be recorded on issues relating to priority and the requirement of claims being fairly based, prior claiming, inventive step, synergy, and sufficiency of disclosure.

Review and key takeaways

The Madras High Court's decision underscores two critical principles in Indian patent jurisprudence.

Firstly, the decision reinforced the importance of Section 11(2) of the Act in determining priority dates. The statutory requirement that a claim must be ‘fairly based on the matter disclosed’ in the provisional specification is not a mere formality and posits significant implications for prior art analysis.

Secondly, the decision emphasized the obligation of the IPO to issue reasoned orders that address all material contentions raised by an Applicant. The procedural failure to record findings on significant objections, particularly those pertaining to the fundamental question of whether a cited document qualifies as prior art, can result in invalidating the order. This is consistent with the principles of natural justice that all adjudicating authorities are mandatorily required to comply with and uphold.

[The authors are Associate and Partner, respectively, in IPR practice at Lakshmikumaran & Sridharan Attorneys, New Delhi]