No issue estoppel in Australian Patent Office proceedings

Nufarm Australia Limited v Corteva Agriscience LLC [2023] APO 40

30 June 2023

Australian Patent Office

Felix White

The common law doctrine of issue estoppel requires that a dispute arising between parties should be decided once and for all¹.  On occasion, the Commissioner of Patents may be tasked with examining issues that have emerged in earlier proceedings before it concerning the same patent application, or a closely related application.  In these instances, issue estoppel does not bind the Commissioner.

Background

This unappealed decision involves an opposition filed by Nufarm Australia Limited against the seventh application (of eight) in a patent family filed by Dow Agrosciences, now known as Corteva Agriscience LLC, directed to low vapour drift herbicides.  The patent family has a history of oppositions and divisional applications, with the present opposition relating to Australian patent application no. 2019253885 (Application) claiming compounds derived from herbicidal carboxylic acids and ammonium hydroxides having reduced volatility compared to commercially available carboxylic acid herbicide salts.

Key Issues

The opponent Nufarm initially submitted a Statement of Grounds and Particulars covering various grounds for opposition and providing 62 prior art documents, however the only grounds pressed were novelty and inventive step based on one prior art document (a Japanese patent referred to as D2).

Of the six earlier filed applications, Nufarm opposed the parent application (1) which was subsequently withdrawn; two divisionals (2 and 3) proceeded unopposed to grant with a narrower claim set; Nufarm’s oppositions against further divisionals were unsuccessful (4) and partially successful (5) in a combined decision handed down in 2020 (unrelated to the present challenge); and Nufarm’s opposition to the sixth application (6) was successful on the grounds of novelty and inventive step based on D2 in a decision handed down in July 2022, following which the sixth application was amended.

The opposed application, as a divisional application (7), shares substance with its predecessors but diverges in specific claims.    A further divisional application (8) remains pending.

Both parties provided written submissions on issue estoppel arising from the earlier opposition decisions.

Both parties concurred that the Commissioner is not bound by estoppel, with Nufarm suggesting that the correct approach had been prescribed by the earlier Patent Office decision in SNF as follows:

“The Delegate should start with the findings of fact made in the previous decisions, and then ask whether there is any evidence that contradicts those findings of fact.  Where there is contradictory evidence, the Delegate will need to decide how much weight to give to each”.² 

The Delegate noted that SNF involved a finding of fact in the Federal Court, unlike the present case which involved previous findings of fact by another delegate.  In any event, he was careful to distinguish findings of fact in previous decisions from both findings of law and the application of the law to the facts.  He considered that questions of construction and of disclosure by the prior art are not questions of fact in the sense referred to in SNF.  The Delegate concluded:

“To sum up, my understanding is there [is] no estoppel before the Commissioner, which as an administrative tribunal is not part of the court system and not part of jurisprudence as such.  While it is no doubt desirable for there to be consistency between decisions, it is inevitable that there will be occasional inconsistencies in decisions delivered by different delegates….. Be that as it may, I will make my decision in this case on the evidence before me.”

Outcome

The Delegate stated his understanding that there is no estoppel before the Commissioner, clarifying that the Commissioner functions as an administrative tribunal that is not part of the court system and nor part of jurisprudence.  While consistency of in office decisions is desirable, differences are inevitable, as there is in fact no duty on the delegates to follow findings of fact from earlier Patent Office decisions.

Ultimately, consistent with the 2022 opposition decision, the opposed claims of the Application were found to lack novelty and inventive step in view of D2 as that document disclosed the specific chemical process central to the reduced volatility of the claimed compounds

Implications

The Delegate affirmed that there is no issue estoppel before the Commissioner in relation to prior Patent Office decisions.  If prior decisions of a delegate are to be relied upon, drawing inferences to similar findings in Court decisions may strengthen their impact.

Given there is an eighth application pending in this family, the parties may find themselves in another dispute over closely related subject matter as issue estoppel will not act to prevent it.

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[1] See SNF (Australia) Pty Ltd v Ciba Specialty Chemicals Water Treatments Ltd [2016] APO 8 (SNF)
[2] Paraphrasing SNF at [52].

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