The Statutory Framework

Australia remains one of the few jurisdictions with a statutory “best method” disclosure obligation where non-compliance is a stand-alone ground of invalidity. Although rarely raised during examination, it has been increasingly relied upon in litigation as a ground of invalidity in recent years.

Section 40(2)(aa) of the Patents Act 1990 (Cth) provides that a complete specification must “disclose the best method known to the applicant of performing the invention”. The foregoing obligation is distinct from sufficiency under section 40(2)(a), as the former is not concerned with whether the skilled person can reproduce the invention, but with whether the patentee has disclosed what it actually knew to be the best way of carrying out the invention at the relevant date.

The requirement is assessed at the filing date of the application and has been applied strictly by the Federal Court. In the case of divisional applications, the point of assessment has historically been the filing date of the divisional; however, a recent decision may signal a shift in practice toward designating the relevant date as the filing date of the earliest complete application. This is discussed further below.

Comparative Perspective

The Australian position contrasts with most major patent systems:

• United States: Until 2011, US patents could be invalidated for failure to disclose the “best mode”. The America Invents Act removed this as a ground of invalidity, though the statutory language remains in 35 U.S.C. §112. In practice, best mode is no longer enforced.
• United Kingdom and European Union: The UK abolished its best method requirement in 1977. The European Patent Convention (“EPC”) contains no equivalent provision; Art 83 EPC requires only that the disclosure be “sufficiently clear and complete” for the invention to be carried out by a skilled person.
• Southeast Asia (e.g., Japan, China, Singapore, Korea): No similar requirement exists as a ground of invalidity.
• India: Retains a similar requirement to Australia under s 10(4) of the Patents Act 1970 (India), with failure to disclose the best method being a ground of revocation and a basis for opposition.
• New Zealand: Retains a similar requirement to Australia under s 39(1)(b) of the Patents Act 2013 (NZ), with failure to disclose the best method being a ground of revocation.

Judicial Consideration of Best Method

Servier v Apotex (2016)

In Les Laboratoires Servier v Apotex Pty Ltd [2016] FCAFC 27, the Full Court held that Servier’s patent for the drug perindopril erbumine was invalid for failure to disclose best method. The specification stated that the arginine salt of perindopril could be “prepared according to a classical method salification of organic chemistry,” but did not provide details of the actual method. The Court held that Servier knew of, but failed to disclose, the particular method actually used. Generic language was insufficient to meet the statutory requirement because a skilled person would have had to engage in “extensive trial and error experimentation”.

BlueScope v Dongkuk (2019)

In BlueScope Steel Ltd v Dongkuk Steel Mill Co Ltd (No 2) [2019] FCA 2117, the patent concerned a steel strip coated with an aluminium-zinc-magnesium alloy. The specification referred to “special operational measures” in the manufacturing process but did not identify what they were. The court held that BlueScope knew of specific measures that achieved the desired alloy composition but had not disclosed them, and the patent was invalidated for failure to disclose best method. Importantly, the court refused to allow post-grant amendment to add these details due to BlueScope’s considerable delay and failure to provide full disclosure to the court.

Dometic v Houghton (2018)

In Dometic Australia Pty Ltd v Houghton Leisure Products Pty Ltd [2018] FCA 1573, the Federal Court considered best method in the context of divisional patents. Justice Burley held that compliance was assessed at the divisional filing date, not the parent filing date. This interpretation meant that if the applicant knew of an improved method between the parent and the divisional filing dates, it needed to be updated and disclosed in the divisional. This created an inherent tension between the best method requirement, and the “Raising the Bar” added subject matter provisions, because the addition of a substantially updated method was likely to amount to impermissible added subject matter.

NOCO v B&W (2025)

The issue of timing was revisited in The NOCO Company v Brown & Watson International Pty Ltd [2025] FCA 887. NOCO had filed an application under the Patent Cooperation Treaty (“PCT”) in July 2014 for portable jump-starter devices. Several divisional applications were later filed in 2020, 2021 and 2022. The respondent argued that because NOCO had developed an improved version of the device by September 2014, the divisional applications should have disclosed such improvement as the best method.

Justice Moshinsky held that the relevant date for assessing compliance with the best method requirement was the filing date of the earliest complete application, in this case, the 2014 PCT, not the divisional application filing dates. His Honour relied on earlier authorities (Rescare Ltd v Anaesthetic Supplies Pty Ltd (1992) 25 IPR 119; Pfizer Overseas Pharmaceuticals v Eli Lilly [2005] FCAFC 224; and Mont Adventure Equipment Pty Ltd v Phoenix Leisure Group Pty Ltd [2009] FCAFC 141 which consistently tied best method disclosure to the commencement of the patent term.

As a result, the NOCO divisional patents were not held invalid for failing to disclose improvements developed after the 2014 PCT filing date. Importantly, Justice Moshinsky stated that it was unnecessary to determine whether Dometic v Houghton (2018) was wrongly decided and expressly refrained from commenting on that case. Whilst the judgment does not explicitly overrule Dometic v Houghton (2018), it is in agreement with the earlier line of authority that the earliest complete filing is the relevant date.

Current Position

Following the NOCO decision, the position in Australia can be summarised as follows:

• An applicant must disclose the best method known at the filing date of the earliest complete specification.
• Non-disclosure is a ground of revocation under section 138(3)(f), even where the specification is otherwise enabling.
• Courts will assess whether the applicant actually knew of a better method and whether the disclosure fairly communicates that method to a skilled person.
• Section 40(2)(aa) is assessed objectively and does not involve good or bad faith; however, where a patentee seeks to amend the specification post-grant to include a best method, courts may, in their discretion, refuse the amendment if the omission appears strategic or would amount to an abuse of process.

Looking Forward

The decision in NOCO v B&W (2025) has been received as restoring, to some degree, certainty to the divisional landscape. By anchoring the best method requirement to the date of filing of the first complete specification, the judgment avoids many of the practical difficulties identified in Dometic v Houghton (2018). Many patentees and prosecutors managing post- “Raising the Bar” divisionals are likely to regard the outcome as a welcome relief.

Nevertheless, caution is warranted. The judgment is a single-judge decision of the Federal Court and remains open to appeal or separate consideration by the Full Court. Challengers may contend that parts of Justice Moshinsky’s analysis were obiter, while emphasising that the reasoning in Dometic v Houghton (2018) was expressed as part of the ratio decidendi. Until the Full Court addresses the issue, neither case formally binds another judge at first instance, which leaves room for further debate. Clarification is likely to come through further judicial guidance or legislative reform.

For the time being, applicants should ensure that specifications filed in Australia disclose not only an enabling method, but the method they consider best as at the filing date, since failure to do so remains a ground of revocation. Applicants should continue to draft with that standard in mind and monitor any appellate or legislative developments that may follow in the wake of NOCO v B&W (2025).