Claim reduction strategies in Canada: A global perspective

9 minute read
30 May 2023

Amendments to the Canadian Patent Rules in October 2022 included the introduction of excess claim fees where there are more than 20 claims in a patent application, resulting in the need for a more strategic approach to patent prosecution before the Canadian Intellectual Property Office (CIPO) in order to reduce the number of claims in a claim set.

Applicants with global patent portfolios are already familiar with the concept of excess claim fees, since many jurisdictions now impose excess claim fees. For example, the United States Patent and Trademark Office (USPTO) imposes fees for claim sets with over 20 claims or for claim sets with more than 3 independent claims. The European Patent Office (EPO) imposes fees for each claim beyond 15 claims, and the Chinese Patent Office (CNIPA) imposes fees for more than 10 claims.

Patent practitioners across the world are also well-versed in claim amendment strategies to reduce large claim sets (often filed at the PCT stage) in order to fit within these jurisdictional limitations and reduce costs for their clients.

While it may be tempting to "repurpose" a reduced claim set prepared for either the USPTO or EPO, there are several peculiarities of Canadian patent practice that mean this approach may not always be advisable.

Double patenting

Double patenting, which refers to the granting of multiple patents for a single invention, is prohibited in many jurisdictions, including in Canada. Canada has both novelty and obviousness-type double patenting doctrines. There is no terminal disclaimer practice as in the United States or any other statutory means that can be used to resolve double patenting in Canada. As a result, it may be fatal for a second patent to grant to the same applicant where the claims are coterminous with a first patent.

However, there are prosecution strategies that can be taken in Canada in order to provide applicants with a defence to allegations of double patenting. In particular, jurisprudence in Canada has held that where a unity objection is raised by an examiner, this will serve as a defence to allegations of double patenting as between a patent that issues from an earlier filed application and a patent that issues from a later filed divisional application claiming subject matter that was divided out in response to the unity objection.[1] Therefore, with the expectation that a unity objection may be raised, it is recommended to consolidate all claims of interest in a single application, and divide out subject matter following a unity objection to insulate issued patents from a double patenting attack.

Since the introduction of excess claim fees, this strategy of including all claims of interest in a single claim set may become prohibitive for certain applications. However, to preserve the ability to file a divisional application in response to a unity objection, applicants are advised to at least include primary independent claims to each invention contained within the application.

Optional language

Many practitioners will be familiar with the keen eye of the Canadian examiner for clarity issues. More often than not, Canadian examiners will object to the presence of optional language in claims ("optionally", "preferably", "such as", "for example", "e.g.", features in parenthesis). Nevertheless, applicants may opt to use optional language to reduce the number of claims in the claim set and decide later which of the optional elements to keep. However, it is of note that avoiding optional language may expedite prosecution and reduce the number of Office Actions.

"Or" clauses

While "or" clauses are generally allowed in Canada, Canadian examiners sometimes object to the use of "too many", "or" or "and/or" clauses in a claim.

Also worth noting is that while "or" clauses should not invoke a clarity objection during prosecution, when it comes to litigation, a claim that recites alternatives may be found invalid if one or more of the alternatives is unpatentable1. Therefore, if "or" clauses are used initially to reduce claim fees, applicants may want to consider amending the claim set again prior to allowance to present embodiments of key importance in stand alone claims.

Maximum three office actions

The new Canadian Patent Rules also introduced a limit of three Office Actions, after which a Request for Continued Examination (RCE) must be filed and further examination fee must be paid. Therefore, it may be beneficial to review and amend claims prior to examination to avoid known clarity issues and/or to add claims to different inventions to prompt a unity objection by the examiner for any subject matter that the applicant may wish to file in a divisional application.


In summary, claim reduction strategies in Canada should be considered independently of other jurisdictions in order to avoid prosecution pitfalls and to streamline prosecution.

If you have any specific questions about this article or would like to discuss it further, you can contact the authors or a member of our Life Sciences Group.

Appendix I: Table comparing excess claim fees across Canada, Europe and the United States and how some claim reduction strategies are examined by the patent office in each jurisdiction

  Canada Europe United States
No. of claims before excess claim fees 20 15 20
No. of independent claims allowed No limit (except for reasons of clarity) 1 independent claim per category (some exceptions) No limit (but excess fees due for independent claims above 3)
Fees for excess claims $100 CAD per claim in excess of 20 €265 for claims 21-50

€660 for claims 51+
$100 USD* per claim in excess of 20

$480 USD* for each independent claim in excess of 3
When are excess claim fees calculated (1) when examination is requested; and

(2) when the Notice of Allowance is issued, payable for any claim above 20 on file at any point during prosecution that was not previously paid
(1) at time of filing; and

(2) when the Intention to Grant is issued, payable for any allowed claim above 15 that was not previously paid
At time of filing
Multiple dependent claims allowed Yes, multiple dependent claims count as one claim Yes, multiple dependent claims count as one claim Yes (but counted as separate claims for each  dependency and excess fee of $860 USD* for each multiple dependent claim)
Double patenting considerations Novelty and obviousness-type double patenting; voluntary divisionals not advised; file all claims of interest in one application when requesting examination in order to invoke a unity objection "Same subject matter" double patenting only Novelty and obviousness-type double patenting; terminal disclaimers available
Optional language allowed Not usually Yes Usually
"or" language allowed Yes Yes Yes
No. of Office Actions 3 Office Actions; an RCE can be filed to obtain a further 2 Office Actions No limit. The applicant may be summoned to attend oral proceedings if it is considered expedient 1-2 Non-Final Office Actions followed by a Final Office Action; an RCE can be filed to continue the examination procedure

*regular entity fee

1 Abbott Laboratories and Abbott Laboratories Limited v The Minister of Health and Apotex Inc, 2005 FC 1332 (clarithromycin); Schering-Plough Canada Inc and Schering Corporation v Pharmascience Inc, Sepracor Inc and the Minister of Health, 2009 FC 1128 (desloratadine).

[1] Consolboard Inc. v. Macmillan Bloedel Ltd., [1981] 1 SCR 504 [Consolboard]

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