Canmar Foods Ltd v TA Foods Ltd: Defining the Scope of Section 53.1 of the Patent Act

De temps en temps nous partageons des travaux « IP News » exceptionnels, écrits pour la classe de Propriété intellectuelle (BUS 502). Vous trouverez celui de Gabrielle Landry et Arvin Khodayari ci-dessous.  

In September 2019, the Federal Court rendered a judgment interpreting and applying the newly added section 53.1 of the Patent Act for the first time in Canmar Foods Ltd v TA Foods Ltd.  [1] This new section states that all written communication between the applicant for a patent and the Canadian Patent Office (CPO) can be used to rebut any representation made by the patentee about the construction of one of the claims of the patent in an action or proceeding. [2] As this section was adopted through an omnibus bill [3] , there is very limited debate and comment on this specific section.

Prior to the adoption of s. 53.1, statements made during the prosecution of Canadian patent applications or their corresponding foreign patent applications where neither relevant nor admissible with respect to construing terms used in the Canadian patents. [4]  The Supreme Court of Canada stated that allowing the use of prosecution history would undermine the public notice function of patent claims. Indeed, the public is entitled to “clear and definite guidance concerning the extent of the monopoly conferred” by a patent. [5] Additionally, the current emphasis on purposive construction was inconsistent with opening the “pandora’s box of file wrapper estoppel” as the focus must be kept on the language of the claims. [6] File wrapper estoppel is a long withstanding US doctrine allowing the use of patent prosecution history to limit the scope of patent claims. [7] 

The litigation in Canmar Foods Ltd v TA Foods Ltd arose between two competitors in the Canadian flaxseed market. The plaintiff, Canmar Foods Ltd (“Canmar”), alleges that TA Foods Ltd (“TA Foods”) has infringed its patent, which protects a specific method for roasting oil seeds and its resulting products. [8] The patent in question is composed of a total of 23 claims, where only one is an independent claim (“Claim 1”). [9] 

TA Foods brought a motion for summary judgment and submitted that its method was different than what was protected by the patent. In fact, it submits that in its process, it did not heat flax seeds in a “stream of air” nor placed the seeds in an “insulated roasting chamber tower,” two elements included in Claim 1 of Canmar’s patent. [10] 

Relying on s. 53.1 of the Patent Act, TA Foods supports its motion for summary judgment by referring to amendments made during the prosecution of Canmar’s patent, notably the introduction of the terms “stream of air” and “insulated or partially insulated roasting chamber or tower” to Claim 1. [11]  TA Foods also refers to the prosecution history of a corresponding US Patent. [12] In fact, the amendments to Claim 1 of the Canadian patent were only made to reproduce amendments filed in the US patent application to overcome issues of novelty and obviousness.[13]  According to TA Foods, these amendments demonstrate that two elements ultimately introduced are essential to Claim 1 of the Canadian patent. [14]  This was ultimately confirmed by the Court.  [15] 

Interpretation of Section 53.1 of the Patent Act

In his decision, Justice Manson concludes that section 53.1 creates an exception to the general rule developed in Free World Trust[16]  In fact, written communications “are only admissible for the limited purpose of rebutting a representation made by the patentee as to the construction of a claim in that patent.” [17]  The Court concluded that the prosecution history was only admissible because the plaintiff made “multiple representations […] to the effect that the language of Claim 1 [was] not limited to a particular type or source of heating.” [18]  Once prosecution history is rendered admissible, it will aid in the purposive construction of the disputed elements of the claim in question. [19]  However, jurisprudence and doctrine will have to clarify Justice Manson’s interpretation of  section 53.1 as it seems to establish a general principle rather than an exception to the general rule of Free World Trust.

The main issue before the Court was defining the scope of admissibility of prosecution history under section 53.1, notably whether the prosecution history of a foreign correspondent patent was admissible as evidence in a Canadian proceeding. [20]  While Justice Manson recognizes that the language of section 53.1 is limited to communications between the patentee and the CPO, [21]  he nonetheless found that foreign prosecution history can be considered in “extraordinary circumstances.” [22]  According to the judge, extraordinary circumstances arise when the patentee acknowledges that the claims of the Canadian patent were amended to reproduce claims submitted in another jurisdiction and that the patentee “admits that the amendments have limited the scope of the claims in order to make the claims novel and non-obvious.” [23]  Only in these circumstances will the Court be able to refer to the foreign prosecution history for the limited purpose of construing the Canadian claims. [24] 

In this case, Canmar made an explicit reference to the analogous US patent application and admitted that the amendments made in the claims of the Canadian patent were filed in order to overcome issues of novelty and obviousness in the corresponding US application. [25]  This qualified as an exceptional circumstance.

Justice Manson justified his reasoning on the fact that ignoring the reference to the United States prosecution history in these extraordinary circumstances “would emasculate the intent and effect of section 53.1.” [26]  It would also incentivize Canadian patent applicants to refrain from being transparent with the CPO as to why certain amendments were made. [27] 

While such an interpretation of section 53.1 is consistent with the American approach [28], it deviates from the clear stipulation in the Patent Act that only written communication between the “the applicant for the patent or the patentee” and the “commissioner, an officer or employee of the Patent Office or a member of a re-examination board” are included. [29] Additionally, the Federal Court had stated in Meda AB v Canada (Health), prior to the adoption of section 53.1, that the inadmissibility of prosecution history was especially true of foreign applications and that a change to this rule should not be affected by the Court but rather through legislative amendments. [30] 

Additionally, Justice Manson’s characterization of “exceptional cases” might be over-inclusive. The reality is that an increasing number of Canadian patent applications are submitted through requests for expedited examination under the Patent Prosecution Highway (“PPH”) procedures. [31]  The PPH allows patent applicants to fast-track the examination of their patent application in a second patent office provided they already have a corresponding application with a PPH partner, and one of the claims has already been found patentable. [32]  The second patent office’s examination will then refer to the search and prosecution results of the first patent office. [33]  In 2018, the Canadian Intellectual Property Office (“CIPO”) received 3,551 PPH requests, which corresponds to an increase of 48.6% from 2017. [34]  Moreover, these PPH requests accounted for 9.8% of the total 36,161 patent applications received by the CIPO in that same year. [35]  This percentage is bound to increase with the renewal of PPH agreements. For example, the CIPO renewed a PPH agreement with the European Patent Office in 2018. [36] Therefore, there is an increasing number of Canadian applications with reference to corresponding foreign applications. Consequently, such inclusion of foreign prosecution history in Canadian patent litigation may force potential international patent applicants to weigh the advantages of simplifying the patent application through the use of processes such as PPH requests with the possibility that their corresponding applications may limit or affect the construction of their Canadian patent claims in future litigation. [37] 

On the other hand, some American scholars have argued that if an applicant puts forth consistent statements and reasoning for the patentability of a particular invention before the CIPO and the foreign office, the prosecution history of the foreign application should not have an adverse impact on the local patent. [38]  However, this circles back to another issue of foreign prosecution history: foreign offices have different practices and legal requirements for patentability. [39]  Consequently, the same statements and reasoning may lead to different correspondences and responses from the foreign patent office than from the CPO.

Difference between US file wrapper estoppel and section 53.1 of the Patent Act

The Court’s interpretation of section 53.1 and the scope of admissibility of foreign prosecution history was heavily inspired by the interpretation of the doctrine of file wrapper estoppel in US patent law. [40]  In fact, the Court refers to multiple United States Supreme Court decisions in its analysis of how prosecution history may be properly used in Canada. [41]  Additionally, the Court’s conclusion that foreign prosecution history was admissible was inspired by the United States Court of Appeals for the Federal Circuit position on the matter. [42] 

However, the degree of importance and relevance of patent prosecution history is much more significant in the United States than what is permitted in the language of section 53.1 of the Patent Act. In fact, prosecution history is considered intrinsic evidence for claim construction in infringing litigation without being limited to the rebuttal of a representation made by the patentee. [43] Furthermore, under the file wrapper estoppel doctrine of the United States, amendments to a patent application create a presumption that such amendments were made for reasons related to patentability and consequently bar the application of the doctrine of equivalents on the particular claim elements. [44] The doctrine of equivalents gives the patentee recourse “against the producer of a device that performs substantially the same function in substantially the same way to obtain substantially the same result.” [45]  The Supreme Court acknowledged in Free World Trust that Canadian patent law shared a similar concept to the doctrine of equivalents. [46] In fact, “a patent owner has a remedy against an alleged infringer who does not take the letter of the invention but nevertheless appropriates its substance (or ‘pith and marrow’).” [47] 

Consequently, the question must be asked whether, absent the clear acknowledgment by Canmar that the amended claims were submitted to “encompass both novel and non-obvious subject matter,” [48]  the Court would have recognized a presumption that the amendments were made to respond to patentability issues and consequently restricting the claim construction, as is the case in the US doctrine of file wrapper estoppel. A complete endorsement of the US doctrine would significantly modify the patent litigation landscape in Canada.

Concluding Thoughts

It is worth noting that Justice Manson’s analysis of the admissibility of foreign applications may have been done in obiter as he granted the summary judgment without considering the prosecution history of the corresponding US patent. [49]  Furthermore, Canmar has already filed for an appeal as of October 24, 2019. [50]  Consequently, the precedential value of Justice Manson’s decision is yet to be confirmed.


[1] Canmar Foods Ltd v TA Foods Ltd, 2019 FC 1233 [Canmar].

[2] Patent Act, RSC 1985, c P-4, s 53.1 [Patent Act].

[3] “Budget Implementation Act, 2018 No. 2”, House of Commons Debates, 42-1, (1 November 2018) (Mr. Joël Lightbound); Bill C-86, A second Act to implement certain provisions of the budget tabled in Parliament on February 27, 2018 and other measures, 1st Sess, 42nd Parl, 2018 (as passed by the House of Commons 3 December 2018).

[4] Meda AB v Canada (Health), 2016 FC 1362 [Meda] citing Free World Trust v Électro Santé Inc, 2000 SCC 66 [Free World].

[5]ABB Technology AG v Hyundai Heavy Industries Co, Ltd, 2015 FCA 181 at para 51, citing Free World, supra note 4 at paras 42-43.

[6] Ibid.

[7] Martin J. Adelman, Randall R. Rader & Gordon P. Klancnik, Patent Law in a Nutshell, 2nd ed (Minnesota: West, 2013) at 278, citing Warner-Jenkinson Co v Hilton Davis Chemical Co, 520 US 17 (1997).

[8] Canmar, supra note 1 at para 3, 8.

[9] Ibid, at para 8.

[10] Ibid, at para 91—94.

[11] Ibid, at para 51, 56.

[12] Ibid, at para 56.

[13] Ibid, at para 57.

[14] Ibid, at para 57.

[15] Ibid, at para 118.

[16] Ibid, at para 60.

[17] Ibid, at para 63.

[18] Ibid, at para 84.

[19] Ibid, at para 85.

[20] Ibid, at para 69.

[21] Ibid, at para 70.

[22] Ibid, at para 73.

[23]  Ibid, at para 74.

[24]  Ibid, at para 74.

[25]  Ibid, at para 70.

[26]  Ibid, at para 71.

[27]  Ibid, at para 72.

[28]  Abbott Labs v Sandoz, 566 F.3d 1282 (Fed Cir 2009) at 1288; Esso Research and Engineering Co v Kahn and Co, Inc, 379 FSupp 205, 183 USPQ 582 (D Conn 1974), aff’d, 513 F2d 1341 (1st Cir 1975) at 212—213.

[29] Patent Act, supra note 2, s 53(b)(i)(ii).

[30] Meda, supra note 4 at para 116.

[31] Paul den Boef, “Getting your patent application into the fast lane: Canada’s patent prosecution highway” (24 January 2018), online: Smart & Biggar <>; “Patent Prosecution Highway Portal Site” (last modified in December 2018), online: Japan Patent Office 


[32] Alicia Pitts & Joshua Kim, “The Patent Prosecution Highway: Is Life in the Fast Lane Worth the Cost” (2009) 1:2 Hastings Science & Technology LJ 127 at p 128; “Patent Prosecution Highway (PPH)—Fast-track examination” (last modified 1 January 2018), online: Canadian Intellectual Property Office <>.

[33] Etienne De Villiers, “The Patent Prosecution Highway: Canada as Office of First Filing” Landslide Magazine 2:3 (January 2010) 30 at p 30.

[34] “Patent Prosecution Highway Portal Site” (last modified in December 2018), online: Japan Patent Office <>.

[35] “Facts and Figures” (last visited on 26 November 2019), online: World Intellectual Property Organization <>.

[36] Canadian Intellectual Property Office, “Extension of the Patent Prosecution Highway pilot agreement between the European Patent Office and the Canadian Intellectual Property Office” (5 January 2018), online: Government of Canada <>.

[37] Amrita V. Singh & Shuo Xing, “Federal Court Unwraps Foreign File Wrapper in Canadian Patent Litigation” (7 October 2019), online: Bereskin & Parr <>.

[38] Michael G Panian, “Use of Foreign Patent Prosecution History as Evidence of Invalidity of a Corresponding United States Patent” (1988) 70:10 J Pat & Trademark Off Soc’y 667 at p 676.

[39] Ibid, at p 668.

[40] Ibid, at para 64.

[41] Canmar, supra note 1 at para 64, citing Warner-Jenkinson Co, Inc v Hilton Davis Chemical Co, 520 US 17 (1997); Canmar, supra note 1 at para 65, citing Festo Corp v Shoketsu Kinzoku Kogyo Kabushiki Co Ltd, 535 US 722 (2002).

[42] Canmar, supra note 1 at para 75, citing Abbott Labs v Sandoz, 566 F3d 1282 (Fed Cir 2009) at 1288.

[43] “Foreign Patent Decisions and Harmonization: A View of the Presumption against Giving Foreign Patent Decisions Preclusive Effect in United States Proceedings in Light of Patent Law International Harmonization” (2018) 18:1 John Marshall Rev of Intellectual Property L [i] at p 6.

[44] Edward F O’Connor, Intellectual Property Law and Litigation: Practical and Irreverent Insights (American Bar Association, 2010) citing Warner-Jenkinson Co, Inc v Hilton Davis Chemical Co, 520 US 17 (1997) at para 14-15; Festo Corp v Shoketsu Kinzoku Kogyo Kabushiki Co, 535 U.S. 722 (2002).

[45] Free World, supra note 4 at para 28 citing Graver Tank & Mfg Co v Linde Air Products Co, 339 US 605 (1950), at p 608.

[46] Free World Trust, supra note 4 at para 28.

[47] Ibid.

[48] Canmar, supra note 1 at para 86.

[49] Canmar, supra note 1 at para 79.

[50] “Court Files” (last visited 12 November 2019), online: Federal Court <>.

This content has been updated on December 16, 2019 at 14:11.