Failure to disclose the ‘best method’ trips up another patent applicant

A recent decision of the patent office, Merial, Inc. v Bayer New Zealand Limited [2018] APO 14, has again highlighted the hazards of failing to “disclose the best method known to the applicant of performing the invention”, as required by section 40(2)(aa) of the Australian Patents Act.

The facts of the case

Opposed application AU2014201152 – a divisional of AU2007334747 – discloses anti-parasitic tablet formulations including both a lipophilic macrocyclic lactone and a water-soluble levamisole salt. The inventors addressed the problem of providing both actives in a single stable and bioavailable formulation by dissolving the lactone sequentially in an organic solvent and a co-solvent, before adding the levamisole and forming the tablet.

The evidence established that the applicants had already developed a commercial manufacturing protocol before filing the parent application, avoiding a high temperature drying step by using low volumes of specific solvent/co-solvents and implementing a low temperature drying step to remove other volatiles. These aspects, which produced a particularly favourable consistency for tabletting while retaining phase separation of the actives, were not disclosed in the specification.

Notably, the evidence of an undisclosed best method was drawn primarily from the inventor’s own declaration in support of the application. Moreover, the applicant had filed another patent application disclosing the full ‘best method’ manufacturing protocol for the identical experimental compositions.

No other ground of opposition was made out. Consequently, the application was found invalid due only to the applicant’s failure to disclose best method.

A rigorous obligation

This case exemplifies Australia’s stringent requirement for patentees to fully disclose an invention for the public benefit in exchange for a monopoly. Legislative changes in 2013 aligned Australia’s ‘sufficiency’ of disclosure requirement with the higher threshold in Europe. However the Patents Act additionally provides a ‘best method’ disclosure requirement for validity not imposed by other major patent jurisdictions.

Recent decisions also caution that the ‘invention’ for which a ‘best method’ must be disclosed is not confined by the features of the claims, but is instead ascertained from the specification as a whole. Moreover, the application may be deficient even if the skilled person can determine the undisclosed best method without undue burden.

Thus, in Kineta, Inc. [2017] APO 45, AU2012315953 directed to new therapeutic compounds was refused for failure to divulge the best method of obtaining the compounds. This was despite evidence that the applicant had simply purchased the compounds from a contract manufacturer without knowledge of the synthetic methodology, and that the synthesis was routine to the skilled person.

Is it fatal?

Failure to disclose the best method is especially problematic since the 2013 Raising the Bar legislation, since a complete specification can no longer be amended after filing to include new matter, such as a ‘best method’ description.

Interestingly, the Merial decision left open questions of whether an added best method disclosure in a divisional application can cure the deficiencies of its parent, and (alarmingly) whether the applicant’s subjective knowledge of best method at the potentially much later divisional filing date might then become the relevant consideration. Apparently testing this option, Kineta has now filed divisional applications of AU2012315953, including a disclosure of the synthetic methodology and source of the new compounds.

Commonly, however, the window for filing a divisional application will have closed before best method validity issues become evident in opposition or revocation proceedings. In such cases, a failure to disclose best method now appears to be fatal.

Best methods for avoiding best method pitfalls

Patent applicants in Australia should thus take great care to disclose the best method known at filing, bearing in mind potential uncertainty as to which aspects might be found relevant to performing the ‘invention’.

When filing an application with a priority claim, applicants should ensure that the specification discloses their current understanding of best method, which may have progressed since the priority application was drafted.

Applicants with multi-faceted and rapidly evolving technology should thus be particularly vigilant, especially when employing an IP strategy that includes both patent filings and trade secrets. Such applicants should carefully assess the risk that a confidential aspect of their technology might later be found to be a best method of their patented invention.

Applicants should also be cautious of publically disclosing information indicating that they were in possession of relevant information not disclosed at filing, for example via academic publications or further patent applications.


Omission of a best method disclosure can have catastrophic consequences for patent applicants in Australia, regardless of any wilful intent to conceal key aspects of the invention. Applicants are thus advised to proactively address best method issues, in collaboration with their Australian patent attorneys, prior to filing their application.

BSc (Hons), PhD Chem, MIP

Matthew is a patent attorney specialising in the chemical sciences and related technology areas. He works with Australian and international clients to protect their inventions across a diverse range of technologies, including polymers, coatings and composites, electrochemical devices, catalysis, minerals processing, materials science, printing and oil and gas technologies. Matthew’s practice includes drafting of patent specifications for Australian universities, research organisations and corporates, and prosecution of local and international patent applications.