Obviousness-type double patenting (“OTDP”) arises when two or more patents or applications include claims that, while not being identical, are not patentably distinct from each other.  In the U.S., OTDP rejections can be overcome by filing a terminal disclaimer that limits the term of the rejected application to be no greater than the term of the disclaimed patent.  In Canada, however, terminal disclaimers are not available to overcome OTDP rejections.  To overcome an OTDP rejection in Canada, the claims can be amended to become patentably distinct, or persuasive arguments can be presented that explains why the pending claims are already patentably distinct.  

Amending the claims to become patentably distinct is not always desirable.  Thus, when developing patent portfolios that will include patents with overlapping subject matter, OTDP rejections in Canada should be avoided.  One way to do so is to include all possible claims in the original application, thereby provoking a Lack of Unity rejection.  The Canadian patent office will then likely respond by grouping all of claims according to each alleged invention, which can then be used as a basis for filing divisional applications that are immune from OTDP rejections. 

It is not necessary to initially file all possible claims when direct filing in Canada or entering the national stage from a PCT application.  For example, new claims can be added to the original application in response to a first Office Action.  Even if a first action Notice of Allowance is received prior to adding such claims, a request for withdrawal along with adding the new claims can be filed to provoke a subsequent Lack of Unity rejection.  Thereafter, the added claims can be canceled, and the original application can proceed to allowance, while divisional applications pursuing the restricted claims can be filed.

To implement this strategy, it may be beneficial to delay examination in Canada while accelerating examination in other jurisdictions.  In this manner, a compilation of related claim sets can be assembled for filing in the original Canadian application.  It should be noted that there are no excess claim fees in Canada for adding claims to an application.  In this manner, a robust Canadian patent portfolio can be created, without concern for OTDP rejections limiting claim coverage.