In a recent post, we highlighted the grave risks of failing to disclose the ‘best method known to the applicant of performing the invention’, as required by section 40 of the Australian Patents Act. A question that was left open was whether such a failure might be remedied by filing a divisional application with the necessary disclosure added to the specification. The recent acceptance of a divisional application indicates that – in the view of the patent office at least – the answer to this question is yes.
Applicants should thus note the possibility of side-stepping a patent validity issue by filing a divisional application which includes an adequate disclosure of best method. It remains to be seen, however, whether the courts will find that section 40 imposes an onerous obligation to disclose the current understanding of best method when filing divisional applications.
In Kineta, Inc.  APO 45, the patent office refused AU2012315953 on the basis that the specification taught no method (and thus omitted the best method) of obtaining the therapeutic compounds claimed in the application. Since the application was subject to the post-Raising the Bar provisions of the Patents Act, the specification could not be amended to add the necessary best method disclosure.
Kineta thus filed divisional application AU2017254812, which disclosed that the compounds had been sourced from a contract manufacturer (known to Kineta when filing the parent) and also described the synthetic methodology (which Kineta did not know at the parent filing date). The application has recently been accepted without objection from the Examiner.
Date when best method must be disclosed?
Although case law is inconclusive on the point, it is generally accepted that the best method disclosure obligation must be fulfilled at the filing date of an application. For a divisional application, however, the further question is whether the relevant filing date is that of the divisional application itself or of the original parent application.
Given the acceptance of AU2017254812 after the refusal of its parent, the patent office has apparently concluded that the relevant date is the divisional filing date. This contrasts with the requirement that an enabling disclosure of the invention must be found in the parent specification if divisional status is to be claimed.
While providing a happy outcome for the applicant in this case, the patent office’s interpretation raises a troubling question: does the applicant have a duty to disclose their current understanding of best method in the divisional specification, or is it sufficient to rectify – at the divisional filing date – the omission of the best method known when filing the parent?
Divisional applications are typically filed many years after the priority date of the original parent application, by which time the underlying technology may have been further advanced or commercialised. In practice, the divisional specification is seldom updated to reflect post-filing developments of the invention. Indeed, such a requirement would be unacceptable to many applicants, given the practical burden of ascertaining current “best method” and the implication that confidential technical or commercial information may need to be divulged.