In an important decision, the Full Federal Court in The NOCO Company v Brown and Watson International 1 held that the relevant date for assessing the best method known to the applicants is the filing date of each divisional application. This judgment carries significant implications for patent filing and litigation strategies, as patentees must consider the adequacy of the best method disclosures in existing and future divisional patent specifications.
Background
As we previously reported, this case involved NOCO’s three patents from the same family for portable vehicle jump starters, which the patentee alleged that Brown and Watson International Pty Ltd (B&W) had infringed.
Each divisional patent claimed a priority date from 2014 based on the PCT application, despite being filed between 2020 and 2022, which is standard practice. In response, B&W cross-claimed for invalidity, including on best method grounds.
Moshinsky J, at first instance, held that the filing date of the earliest complete or PCT application was the relevant date at which the best method known to the patentee was to be assessed.2
Best Method is Assessed at the Filing Date for Divisional Patent Application
Best method is a uniquely Australian validity requirement and a powerful ground of revocation – a patent can be revoked if the complete specification does not “disclose the best method known to the applicant of performing the invention“.3
The key issue for determination by the Full Court was when does the best method need to be disclosed for divisional applications – the filing date of the PCT or the filing date of each divisional patent application?
Having regard to previous Australian cases, including Dometic Australia v Houghton Leisure Product 4, the Patents Act 5 and policy arguments, the Full Court held that the relevant date was the filing date of each divisional application.
The Court found nothing “unjustifiably asymmetrical” in requiring a patentee who had expanded the claimed monopoly in a divisional to also disclose the best method known at that later date. Indeed, “not to require such disclosure would be at odds with the policy underpinning s 40(2)(aa) and would allow the patentee to withhold knowledge of the best method known at the later time“.6
Practical Implications – What You Need to Know
- Patentees managing large divisional families face heightened obligations as each Australian divisional must disclose the best method known to the applicant at that later filing date, even if years have passed since the parent priority document.
- Now is, therefore, the time for patentees (and challenger parties) to evaluate such portfolios, given that best method is a powerful ground of revocation, particularly against divisional patents filed well after the original priority date.
- While most jurisdictions limit the addition of new material during the patent process, this decision places a positive obligation on Australian applicants to add matter in a divisional application, where it relates to the best method of performing the invention.
