What is a divisional patent application?

A divisional patent application may be filed to divide a patent application into two or more patent applications from a "parent" application. The divisional patent application will proceed as a separate application and undergo separate examination. A first divisional patent application is termed a "child" application, and a second or further divisional patent application is termed a "grandchild" application (and "great-grandchild", etc, for further divisionals) if derived from the first divisional application, although this nomenclature is somewhat informal. In some jurisdictions this practice is termed a "cascade of divisional applications". A divisional patent application usually inherits the priority rights from the parent application, which in turn derives priority rights from any priority application(s).

Reasons to file a divisional patent application

There are many reasons why an Applicant would want to file a divisional application. For example:

  • to pursue a second invention that is disclosed in the parent patent application, i.e., if a "unity" objection is taken during prosecution the second invention will need to be removed from the claims, and then it will be possible to file a divisional application to pursue that second invention,
  • to pursue claims that define a narrower form of the invention, and which may be specifically tailored to capture an alleged infringer,
  • if there have been issues during prosecution which have caused the allotted time within which to prosecute the application to acceptance/allowance to run out (e.g., novelty, inventive step or manner of manufacture objections),
  • as an opposition/litigation tactic – it is a strategy to file divisional applications immediately before acceptance of valuable or contentious patents, and/or
  • to delay acceptance because the equivalent applications are not yet allowed in other jurisdictions, such as Europe, US, China or Japan.

If the patent application is, or might be the subject matter of litigation, it is often important to file a divisional application to keep an application pending in case validity issues arise with the litigated patent, as those issues might potentially be rectified in the divisional.

Another reason may be if there are ongoing commercial negotiations relating to the technology. In this case, it might be beneficial for the potential licensee to have a pending divisional application where it has the freedom to amend the claims to suit its particular commercial objectives.

Divisional patent practice before the Australian Patent Office

The Australian Patent Office is relatively accommodating in relation to filing divisional applications, in that there is no limit to the number of divisional applications that can be filed, provided of course that the divisional application is filed within the relevant deadline. In particular, the child divisional application must be filed before either of the following:

  • before the acceptance deadline of the parent application, which is 12 months from issuance of the first examination report; or
  • if the application is accepted, 3 months from the advertisement of the acceptance of the parent application.

This can be contrasted with some other jurisdictions that place restrictions on the filing of divisional applications, such as New Zealand, in which any and all divisional applications must be filed within 5 years of the filing date of the parent application (and examination must also be requested of those divisional application(s) by that 5-year deadline).

Australian practice in relation to management of divisional patent applications is, however, now set to change.

Recently, the Australian Patent Office published a page on its Patent Examiner's Manual1 to introduce a new process for managing divisional applications. In particular, first examination reports issued on divisional applications with great-grandparent or earlier ancestors:

...are to be treated as equivalent to adverse third reports, and are therefore to be reviewed by a supervising examiner. If the supervising examiner is of the opinion that no progress is being made, the case should be discussed with the Supervising Examiner (Patent Oppositions), including whether to set the matter for hearing or case manage the application to ensure a prompt resolution of its status. In certain situations, it may be appropriate to also consider case management or setting matters for hearing where no progress is made in grandparent and parent applications.

In other words, first examination reports (of this kind) will be treated as third examination reports, which as a matter of procedure are always reviewed by a Supervising Examiner, and if the Supervising Examiner deems there has been no progress in the parent, grandparent and great-grandparent applications can recommend case management or a hearing to achieve prompt resolution. In making this change, the Patent Office is now expecting the Applicant to actively prosecute divisional applications (of this kind) to a "resolution". It is generally preferable that third parties are not encumbered by the eternal pendency of divisional-upon-divisional-upon-divisional (i.e., daisy chaining), and this subtle shift in Patent Office procedure is likely aimed at minimizing this practice.

Divisional practice recommendations

It is common for patent Applicants to either:

  1. file a divisional application with the claims of the parent application and to request examination on those claims (with the expectation of the first examination report merely repeats the first examination report on the parent application), or to
  2. file a divisional application with amended claims and have those amended claims examined in the first examination report.

It seems as though the former practice is now frowned upon if it is a divisional application of a great-grandchild application, as it is likely that the Patent Office will conclude that "no progress is being made", which will precipitate the matter being set for hearing or case management "to ensure a prompt resolution of its status".

Accordingly, it is now preferable for divisional applications (with a great-grandparent application) to review the prosecution histories of the parent, grandparent and great-grandparent applications before filing or shortly thereafter, and presenting claims that arguably make some progress towards acceptance of the application, thereby avoiding the new divisional application case management process, which will add costs, unnecessary complexity and uncertainty.

At Spruson & Ferguson, we have a number of highly experienced attorneys who can assist in navigating these complexities. The content of this article is general in nature and must not be relied on in lieu of advice from a qualified professional in respect of your particular circumstances.


1 https://manuals.ipaustralia.gov.au/patent/

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.