This article was prepared with the assistance of Katherine (Katie) Graham.
Unity of invention and double patenting law and practice in Canada can create challenges for patent applicants. For example, applicants may not expect a unity of invention objection to be raised, requiring claims to be cancelled from an application and, if so desired, pursued separately in one or more divisional applications. Conversely, applicants may wish to pursue separate applications to protect related or similar subject matter, and in so doing may attract double patenting issues during prosecution of pending applications or enforcement of patents.
In this article, we discuss practical strategies for navigating unity of invention and double patenting issues in Canada, tailored towards specific objectives for patent protection in Canada.
Double patenting in Canada
The Canadian Patent Act specifies that a patent shall be granted for one invention only.1 Where an application describes more than one invention, the claims may be limited to one invention only, and any other invention disclosed may be made the subject of a divisional application.2 One invention includes a group of inventions linked in such a manner that they form a single inventive concept.3
The Supreme Court of Canada has held that the prohibition against double patenting includes both “same invention” double patenting, where the claims of a second patent are identical or coterminous with those of the earlier patent; and “obviousness” double patenting, which prohibits the issuance of a second patent with claims that are not patentably distinct from those of the earlier patent.4 Both are prohibited and, unlike in other jurisdictions, both are treated identically.
The prohibition against double patenting originally began in Canada, as in many other jurisdictions, to avoid the so-called “evergreening” problem, in which a subsequent patent issues with claims that improperly extend a patentee’s monopoly beyond the original patent term.5 This problem arose under the pre-1989 provisions of the Patent Act, according to which patent protection ran from the date of issue rather than the date of filing, as it now does under the post-1989 provisions.6
Although evergreening may have been the classical driver for the double patenting prohibition in Canada, courts have also acknowledged that this is not the only consideration behind the prohibition, and that double patenting remains an issue in Canada even when the filing dates (and therefore expiry dates) of different applications are the same, such as in the case of a parent-divisional patent family. For example, the Federal Court has noted that regardless of whether “the sin of double patenting” still exists, a patent holder should not be able to receive additional patents for the same invention.7
Patent Term Adjustment, which has recently been introduced in Canada, also creates the potential for different expiry dates for a parent-divisional patent family.
Of note is a key difference between Canadian and U.S. practice concerning double patenting. Under U.S. patent law, an applicant can file a terminal disclaimer to disclaim the non-overlapping term of a later-issued patent. However, although terminal disclaimers have been available for many years in the U.S., they are not available in Canada.
Prosecution strategies
In many situations, applicants may wish to take a proactive approach that reduces the risk of double patenting by attracting a unity of invention objection during prosecution. A unity of invention objection provides a clear path for pursuing one subset of claims in a parent application, and then filing one or more divisional applications to pursue other claim subsets that are not maintained in the parent application. The unity of invention objection provides a strong counter-position against a subsequent attack based on double patenting between the divisional(s) and the parent, or between multiple divisionals. Pragmatically, double patenting issues can be much more challenging to overcome in voluntary divisional applications, which are filed without first receiving a unity of invention objection, though the test, in theory, remains the same.8
Double patenting issues may arise not only during prosecution of applications, but also or instead during litigation, and can invalidate claims or even entire patents, either for double patenting or for contravention of subsection 36(1) (improper divisional).9 This provides a further incentive for applicants to present claims to all disclosed subject matter that is potentially of interest in a single application, and to incur a unity of invention objection early on in prosecution.
We note anecdotally that the Canadian Patent Office appears to be raising objections for improper divisional applications much more frequently now than in the past. These objections are often raised in combination with parent-divisional double patenting objections. Conversely, the courts have only considered the issue of improper divisionals in a few cases in recent years.10 This may be primarily due to the increased number of such objections in prosecution, which are resolved long before the courts are involved.
A proactive strategy to attract a unity of invention objection may not be of interest to all applicants—more patents means costlier prosecution, more maintenance fees, and increased portfolio management overhead. Of note, Canada now charges excess claim fees, and therefore including claims directed to multiple disclosed inventions in a single application may be costly, though there are strategies to mitigate this cost, including removing dependent claims until after the divisional is filed, and combining alternative embodiments into a single claim.
The unity of invention position that will be taken by any particular Patent Examiner is difficult to predict. Though Examiners often follow any unity analysis from an International Search, or restriction requirements in U.S. prosecution, it is possible that an unexpected unity of invention objection may be raised, or a desired unity of invention objection will not be raised. In the former example, an applicant may be able to traverse a unity of invention objection based on a common inventive concept that links the claims. In the latter example, there are actions that may help attract a unity of invention objection to mitigate the risk of a double patenting objection, which can be otherwise difficult.
We discuss several strategies for potentially avoiding or attracting unity of invention objections in Canada, either of which may be appropriate depending on objectives for patent protection in Canada.
Avoiding a unity of invention objection
Not every patent application will have a business case to justify a multi-patent protection strategy. Some applicants may not be interested in obtaining multiple patents, for any of a variety of reasons. In these instances, an applicant may want to avoid a unity of invention objection during prosecution, so that protection for all of the disclosed subject matter of interest can be pursued in a single application.
One of the most effective strategies for reducing the likelihood of a unity of invention objection is to include only one independent claim per category (e.g., only one independent method and one independent apparatus claim) in the application. This strategy may help ensure that all of the claims share a common inventive concept.
However, in some situations it may still be desirable to include multiple independent claims per category. For example, an application may include independent claims (e.g., method and apparatus claims) for each of a transmitter and a receiver. Such related independent claims are permissible if linked by a common inventive concept.
These strategies to limit independent claims by category and related technology generally align with European practice, where applications typically include only one independent claim per category.11 EPC Rule 43(2) does set out exceptions to this practice, such as including more than one independent claim per category where the application involves a plurality of interrelated products or different uses of a product or apparatus, as in the transmitter-receiver example discussed above.12
With a limited independent claim strategy, a unity of invention objection may be less likely, but ultimately the test is whether the claims share a common inventive feature. Any improper unity of invention objection should be successfully traversed on this ground.
Attracting a unity of invention objection
When the objective is to pursue protection in multiple patents, it is a long-standing principle in Canada that a preceding unity of invention objection provides the best protection against subsequent improper divisional or double patenting issues. However, this approach is more expensive now that excess claim fees and a Request for Continued Examination (RCE) practice have been introduced—Applicants can no longer include large claim sets in an application without incurring significant per-claim charges (currently about CAD$120 per claim for any claim over 20). This presents a challenge when balancing cost with benefit, since it is generally desirable to include claims to all disclosed subject matter that is of interest, with a view to attracting a unity of invention objection.
Given that Canadian applicants are required to file an RCE (with an additional fee) after the third Examiner’s Report and each second subsequent Examiner’s Report after the first RCE, it is usually in an applicant’s interest to attract a unity of invention objection as soon as possible during prosecution. In many instances the Examiner will defer a search and substantive examination of the claims until after the applicant has elected a preferred claim group. Therefore, under the current RCE regime, it is possible that fewer Examiner’s Reports covering substantive issues other than unity of invention will be issued before additional examination fees are incurred, potentially prolonging examination and also making examination more costly if only unity of invention is considered in one or more Examiner’s Reports.
In light of these aspects of Canadian practice, there may be particular interest in developing prosecution strategies that are intended to help balance the advantage of receiving a unity of invention objection against likely increased prosecution cost and time.
One strategy to increase the likelihood of a unity of invention objection is to include, in one application, separate independent claims that are directed to the intended focus of each potential divisional application. The very fact that a single application includes different independent claims may itself encourage the Examiner to consider unity of invention.
Independent claims may also be drafted in a way that the differences between the claims are apparent to the Examiner from the claim structure. For example, two independent claims directed to different inventions may be drafted with a similar structure, as follows:
X. A method comprising: performing step A; performing step B; and performing step C.
Y. A method comprising: performing step A; performing step B; and performing step D.
In this example, the differences between the two independent claims (step C versus step D) should be readily apparent to the Examiner.
As well, applicants may consider avoiding “bridging” claims that combine features of the different independent claims. In the example above, steps C and D are intended to be distinguishing or inventive features, and accordingly the applicant may wish to avoid including the following dependent claim:
Z. The method of claim X, the method further comprising performing step D.
Rather than including such a dependent claim or another independent claim that combines step C with step D and potentially obfuscates the intended non-unity between separate inventions, bridging claims may be reserved for a divisional application if the “combined” subject matter is of interest.
Furthermore, reserving any bridging claims until after a unity of invention is addressed may also help reduce the claim count, and excess claim fees, in the claim set that is first examined. There may be prosecution cost and time advantages as well, in that bridging claims can complicate a unity of invention assessment and waiting to present such claims can potentially avoid multiple Examiner’s Reports that deal only (or primarily) with unity of invention.
Other strategies for attracting a unity of invention objection include engaging the Examiner, by telephone and/or in writing, to suggest that a unity of invention objection may be appropriate. The applicant could even go so far as proposing claim groups for the Examiner. For example, in a patent family that includes multiple U.S. patents, the applicant may wish to also have separate counterpart Canadian patents that align with the U.S. patents, and claim groupings consistent with the U.S. claim sets could be proposed to the Examiner in Canada.
In an even more proactive approach, the applicant may convey a “preliminary” election of a particular subset of claims to the Examiner. This may help avoid receiving an Examiner’s Report that raises only unity of invention and defers the search and substantive examination to a subsequent Report. For example, the applicant might already have a preferred prosecution strategy (e.g., to pursue the broadest claims first), and the Examiner could be advised as to the claims that the applicant wishes to have examined if indeed a unity of invention objection is raised. This approach may help avoid “sacrificing” an Examiner’s Report on a unity of invention objection alone. If the Examiner is aware of the applicant’s preference between claim groups, then the Examiner might then be inclined not to defer a search and further substantive examination until after the unity of invention objection is addressed, thereby potentially avoiding a subsequent RCE and shortening prosecution time.
Conclusion
Double patenting issues can present more of a challenge for voluntary divisional applications, and therefore while Canada does not offer terminal disclaimers, attracting a unity of invention objection may be the best approach for many applicants to proactively deal with potential double patenting issues. Other applicants may wish to avoid unity of invention objections altogether and obtain only a single patent. Especially within the current context of excess claim fees and RCE practice, the strategies outlined in this article may help mitigate double patenting risks and reduce prosecution costs and timelines.
The preceding is intended as a timely update on Canadian intellectual property and technology law. The content is informational only and does not constitute legal or professional advice. To obtain such advice, please communicate with our offices directly.
References
1. Subsection 36(1) of the Patent Act: “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.”
2. Subsections 36(2) and 36(3) of the Patent Act.
3. Section 88 of the Patent Rules: “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.”
4. Whirlpool Corp v Camco Inc, 2000 SCC 67 at paras 65-66.
5. Ibid at para 63.
6. See, e.g., GlaxoSmithKline Inc v Apotex Inc, 2003 FCT 687 at para 89, discussing Whirlpool Corp v Camco Inc, 2000 SCC 67 at para 63.
7. GlaxoSmithKline Inc v Apotex Inc. 2003 FCT 687 at paragraphs 91. For other examples of the harm which may result from divisional applications, see also Bayer Inc. v. Canada (Minister of National Health and Welfare) 154 F.T.R [(1998), 82 C.P.R. (3rd), 359 (F.C.T.D.), aff'd (2000), 6 C.P.R. (4th), 285 (F.C.A.] at paragraph 33; Apotex Inc v Merck & Co 2006 FCA 323 at para 49.
8. For more information on divisional applications in Canada, see our article "Double patenting: A comparative guide between U.S. & Canadian practice".
9. See Merck & Co v Apotex Inc, 2006 FCA 323, 55 C.P.R. (4th) 1 (F.C.A.) at para 49.
10. The most recent authority on this issue still remains Merck & Co. v. Apotex Inc., 2006 FCA 323, 55 C.P.R. (4th) 1 (F.C.A.). Although Biogen Canada Inc v Taro Pharmaceuticals Inc, 2020 FC 621 at paras 105-107 and 197-199 suggests that a patentee may be prejudiced by a divisional application that was not forced (rather than by way of a final action issued by the Patent Office), the more recent decision in NCS Multistage Inc v Kobold Corporation, 2023 FC 1486 at para 245 advocates a more balanced middle ground: “The preferred approach is an informed middle ground. Where an inventor can trace the origin of the divisional back to a direction of the Commissioner, it will be immune from double patenting attacks. However, where a voluntary divisional has been made by the applicant, at their cores the divisionals must disclose different inventions to avoid double patenting attacks. An applicant should not be penalized for electing for a divisional, but such an election should not be a mere attempt to secure the claims and take advantage of the earlier priority date of the parent patent.”
11. See point 4.2.021 of the European Patent Guide.