Divisional Patent Applications in Canada

Divisional patent applications in Canada

This article explores the particularities of filing divisional patent applications in Canada.  Unlike other jurisdictions like Europe or Japan, it is not recommended in Canada to file a voluntary divisional application.  In Canada, it is only advisable to file a divisional application if the examiner has raised a unity objection during the examination.  If a divisional application is filed voluntarily, however, the Canadian Intellectual Property Office (CIPO) will not reject the application on this basis.  CIPO will accept the filing of a voluntary divisional application and will proceed to examine it like any other application but any resulting patent that is granted from a voluntary divisional application may be considered invalid for double patenting in view of Canadian jurisprudence.  Canada also does not have a continuation practice like the US.   Thus, when a notice of allowance is received and further claims are desired, the only recourse for the applicant is to file a Request for Continued Examination with a voluntary amendment to introduce further claims.  It is therefore highly advisable to include all claims when the application is first filed or, at the very least when the request for examination is made. 

The basis for a divisional application is found in the Patent Act in section 36(1), which reads as follows:  

“36 (1) A patent shall be granted for one invention only, but in an action or other proceeding, a patent shall not be deemed to be invalid by reason only that it has been granted for more than one invention.”

This provision of the Patent Act is to be interpreted in light of section 88 of the Patent Rules, which reads as follows: 

“88. For the purposes of section 36 of the Act, one invention includes a group of inventions linked in such a manner that they form a single general inventive concept.”

It is important to note that the feature that links the claims must be inventive.  Thus, Canadian examiners will often cite prior art to show that the common features are not inventive features but instead are features of the prior art.  

It is permissible in Canada to have different categories of claims (e.g. system, method, computer-readable medium, etc.) in the same application provided that these claims are unified by a common inventive feature.  Unlike US examiners, Canadian examiners will not cite different patent classifications as a basis for a unity objection.  Also, unlike US examiners, Canadian examiners will not raise the issue of an undue search burden as the grounds for a unity objection.  

In Canada, it is also permissible to file a second divisional application from a first divisional application.    It is also permissible to file parallel divisional applications if the unity objection identifies three or more groups of claims defining distinct inventions.  Accordingly, in Canada, divisional applications may be filed serially or in parallel.  

When raising a unity objection, Canadian patent examiners will often proactively examine the novelty and inventiveness of a first group of claims on the presumption that the applicant is likely to select that first group of claims for examination while withdrawing the other groups of claims.  The applicant is permitted, one time only, to select a different group of claims for examination.  The examiner will then proceed to examine the selected group of claims and will issue a further examination report.  The applicant may not later revert to the originally examined claims or select a different group of claims in that particular application.  

When filing a divisional application it is permissible to include claims to an inventive feature that was not originally claimed.  However, the applicant must be careful not to amend the claims later during prosecution to overlap with the claims of either the original application or any of its divisional applications.  Consider the following example.  An original application is filed with a first group of claims to an inventive feature A and a second group of claims to an inventive feature B.  The examiner raises a unity objection that the application contains two distinct inventions.  The applicant retains the claims to feature A in the original application and deletes the claims to feature B from the original application.  The applicant files a divisional application to feature B.  The applicant may include claims in the divisional application to a new feature C that was not previously claimed but which was nonetheless properly disclosed in the original application.  Alternatively, the applicant may add claims to feature C to the original application, provided it is still pending while filing a divisional application to claim only feature B.   

An application must be pending (i.e. neither granted nor irrevocably abandoned) in order to file a divisional application from that application.  If the application has been abandoned and is eligible to be reinstated, it is permissible to file a divisional if the application is still within the one-year period for reinstatement.  In such a scenario, it is not necessary to reinstate the abandoned application.  Likewise, once the application is granted as a patent, it is no longer possible to file a divisional application.  As a practical matter, since there is no issue notification in Canada like in the US, a divisional application should be filed at the time the final fee is paid.    

A divisional application is considered to be a separate and independent application in accordance with section 36(4) of the Patent Act.  This means that upon filing a divisional application, all maintenance fees must be retroactively paid.  The divisional application is deemed by law to have the same filing as the original application from which it has been divided.  Since the original application and the divisional application are deemed by law to have the same filing date, they both have a maximum term of 20 years and thus expire at the same time, assuming all maintenance feeds are paid for the full lifespan of the patents.  However, it is not necessary to keep both the original application and the divisional application in force by paying maintenance fees on both.  The patent owner may choose to let one of the two lapse by ceasing payment of maintenance fees while maintaining the other one in force. Since patents granted on the original patent application and a divisional application are considered separate and independent, it is possible to sell or license one of the two without selling or licensing the other one.  

The above is intended to provide a general overview of divisional patent practice in Canada for informational purposes only.  The reader is advised not to rely upon this as specific legal advice but rather to consult a registered Canadian patent agent.