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Double Patenting in Canada

By: Christopher Heer, Michelle Huong | Last updated: October 24, 2022
Double patenting is prohibited in Canada. The rule against double patenting prevents the grant of more than one patent on a single invention. As articulated in Abbott Laboratories v. The Minister of Health, 2009 FC 648, a second patent cannot be justified unless its claims are novel over the claims of the first patent. In other words, further invention is required on the first invention to obtain a second patent. The purpose behind the prohibition of double patenting is to prevent an applicant from “evergreening” their patent monopoly, in order to maintain the patent bargain (i.e., the inventor is granted a limited monopoly in exchange for public disclosure of the invention).

During the patent prosecution process, the issue of double patenting may arise where two patent applications (or one patent application and one patent), belong to the same applicant. Applicant is defined in section 2 of the Patent Act to include “an inventor and the legal representatives of an applicant or inventor”, where legal representatives include “heirs, executors, administrators of the estate, liquidators of the succession, guardians, curators, tutors, transferees and all other persons claiming through applicants for patents and patentees of inventions or through holders of certificates of supplementary protection.”

Types of Double Patenting in Canada

There are two types of double patenting in Canada: (i) Same invention double patenting and (ii) Obviousness-type double patenting. Same invention double patenting occurs when the two set of claims that are being compared are “identical or conterminous”. In other words, the subject matter claimed is exactly the same. Obviousness-type double patenting occurs when the second, later set of claims are not “patently distinct” from the claims of the earlier patent.

A patent examiner will compare the claims to determine if double patenting is at issue. This comparison of claims is not literal, but rather, the claims are constructed in a purposive manner based on how a person skilled in the art would have understood the claims in light of their common general knowledge. Where the two sets of claims, constructed in a purposive manner, are such that that second, later set of claims is being anticipated or rendered obvious by the earlier set of claims, then the claims are not “patently distinct” from one another. Where the claims are not “patently distinct” from one another, the requirements for either type of double patenting is met.

How to Deal with Double Patenting Objections During The Patent Prosecution Process In Canada

Applicants may choose to pursue a proactive strategy and take steps at the filing stage to reduce the odds of receiving a double patenting objection. For example, applicants may choose to consolidate claims from all related patent applications into a single patent application. By doing so, applicants may increase the likelihood of obtaining a lack of unity of invention objection by the examiner. In turn, this objection will enable the applicant to elect and proceed with a subset of claims, and subsequently file a divisional application for the remainder of the claims. The advantage of this divisional application is that it will not be subject to a double patenting objection by the Patent Office or by a court. Prior to October 3, 2022, excess claims fee only applied at the time of allowance, making it feasible for applicants to employ the above strategy without having to pay the excess claims fee. After October 3, 2022, excess claims fees apply when the number of claims by the applicant exceeds 20, at any time during the examination process. In other words, for applicants who choose to consolidate all the patent claims into a single application must pay excess claims fee if those claims exceed 20.

Applicants who receive a double patenting objection during the prosecution process may choose to respond by amendment, argument or abandonment. Applicants could amend either one of the patent applications such that the overlapping subject matter is only claimed in one application.

Alternatively, for an obvious-type double patenting objection, applicants may advance arguments that the earlier set of claims do not render the second, later set of claims obvious. An obviousness-type objection is likely to be raised where, for example, the second, later set of claims is merely an aspect or embodiment of the first application. However, as in the case of many pharmaceutical patent applications, a second patent application that relates to a selection invention is not per se invalid for double patenting. Selection patents applications, which typically identify an advantageous narrow species of compounds, are filed following a first patent claiming a broad class of compounds (i.e., genus of compounds).

Another option is for applicants to abandon one of the two patent applications.

Comparison Of the Approach To Double Patenting In Canada And The United States

Similar to Canada, double patenting is not allowed in the United States. While both jurisdictions have similar approaches to double patenting, there are some key differences noted in the chart below.

CanadaUnited States

Same invention double patenting

  • Prevents the grant of more than one patent on the same invention
  • Occurs when the two sets of claims compared are “identical or conterminous”, that is, they claim the same subject matter

Statutory double patenting, also known as same invention double patenting (35 USC 101)

  • Prevents the grant of two patents on the same invention
  • Occurs when the two sets of claims claim identical subject matter

Obviousness-type double patenting

  • Occurs when the two sets of claims are not “patently distinct” from one another
  • There is no terminal disclaimer equivalent in Canada
  • This type of objection is overcome by addressing the overlapping claims either by argument, amendment or abandonment

Non-statutory or judicially created (extension of 35 USC 101) double patenting, also known as obviousness-type double patenting

  • Occurs when the second, later set of claims is obvious with reference to the subject matter of the claims in the first patent, in view of the prior art (In re Longi, 759 F.2d 887, 893 (Fed. Cir. 1985)
  • Filing a terminal disclaimer can overcome a non-statutory double patenting objection. The terminal disclaimer is a statement by the owner of the two patents (or patent applications) that they will “[disclaim] or [dedicate] to the public the entire term or any terminal part of the term of a patent or patent to be granted (filed in an application)”. In other words, the owner will not claim the non-overlapping term of the second, later patent (or patent application when granted).

Divisional Applications

  • The claims of voluntary divisional applications filed must be “patently distinct” from the prior, parent application
  • There is no continuation application equivalent in Canada

Continuation Applications

  • A continuation application is typically used to file additional claims relating to an invention that is disclosed in a prior, parent application.
  • A continuation application is distinct from a Canadian voluntary divisional application. Also, it may be distinguished from a U.S. divisional application, whereby the additional claims need to be “distinct” or of independent invention, apart from the prior, parent application.


If you would like assistance with overcoming a double patenting objection or have further questions on how to avoid double patenting, contact us today for a complimentary and confidential initial telephone appointment.