In Canmar Foods Ltd v TA Foods Ltd, 2019 FC 1233 (September 25, 2019), the Federal Court of Canada, for the first time, interpreted the new file wrapper estoppel provision, section 53.1 of the Canadian Patent Act. The Court held that a foreign prosecution history is admissible in extraordinary circumstances when purposively construing claims.
Claim Construction and Use of Prosecution History in Canadian Patent Law
Under Canadian patent law, claim construction is a matter for determination by a judge. The principles of claim construction to be used by a judge were laid out by the Canadian Supreme Court in 2000 in Whirlpool Corp v Camco Inc., 2000 SCC 67 at paragraphs 49-55 (Whirlpool) and Free World Trust v Électro Santé Inc, 2000 SCC 66 at paragraphs 44-54 (Free World Trust). These principles are:
i. Claims are to be read in an informed and purposive way, with a mind willing to understand and be viewed through the eyes of a position of ordinary skill in the art (POSITA), as of the date of publication, having regard to the common general knowledge;
ii. Adherence to the language of the claims allows them to be read in the manner in which the inventor is presumed to have intended, and in a way that is sympathetic to accomplishing the inventor’s purpose, which promotes both fairness and predictability; and
iii. The whole of the specification should be considered, in order to ascertain the nature of the invention, and the construction of the claims must be neither benevolent nor harsh, but instead should be reasonable and fair to both the patentee and the public.
Until the enactment of section 53.1, statements made during prosecution of a Canadian patent application were neither relevant nor admissible with respect to construing terms used in issued patents (Meda AB v. Canada (Health), 2016 FC 1362 at para 115, citing Whirlpool and Free World Trust). In fact, in Free World Trust, Justice Binnie firmly rejected the use of prosecution history in construing patent claims. In his view, “purposive construction, which keeps the focus on the language of the claims, seems also to be inconsistent with opening the Pandora’s box of file wrapper estoppel” (Free World Trust at paragraph 66).
New section 53.1 became effective on December 13, 2018. This section provides a limited exception to the general rule that prosecution history is not admissible evidence in an action or proceeding involving a patent. This section states:
53.1 (1) In any action or proceeding respecting a patent, a written communication, or any part of such a communication, may be admitted into evidence to rebut any representation made by the patentee in the action or proceeding as to the construction of a claim in the patent if
(a) it is prepared in respect of:
(i) the prosecution of the application for the patent,
(ii) a disclaimer made in respect of the patent, or
(iii) a request for re-examination, or a re-examination proceeding, in respect of the patent; and
(b) it is between
(i) the applicant for the patent or the patentee; and
(ii) the Commissioner, an officer or employee of the Patent Office or a member of a re-examination board.
Now, as a result of the enactment of section 53.1, purposive construction of patent claims in Canada involves three prongs: (1) the claims themselves; (2) the specification; and (3) the prosecution history in Canada (when used to rebut a representation made by the patentee as to the construction of a claim in a patent).
Canmar Foods Ltd v TA Foods Ltd
The plaintiff, Canmar Foods Ltd, (Plaintiff) is the owner of CA Patent No. 2,582,376 (the ‘376 patent) entitled “Methods for Roasting Oil Seed, and Roasted Oil Seed Product.” The ‘376 patent has 23 claims, including claims for methods of roasting oil seed and products produced by these methods. Claim 1 is the only independent claim. The remainder of the claims either directly or indirectly depend on claim 1, which reads as follows:
- A method for roasting oil seed, the method consisting of the following steps:
(a) heating the oil seed in a stream of air for less than 2 minutes, wherein the stream of air has a temperature from 146°C to 205°C, thereby to provide heated oil seed;
(b) transferring the heated oil seed into an insulated or partially insulated roasting chamber or tower;
(c) maintaining the headed oil seed in said roasting chamber or tower without addition of further heat until the roasting process is complete, wherein the temperature of the heated oil seed falls during a maintaining period; thereby to produce a roasted oil seed in the roasting chamber or tower;
(d) removing the roasted oil seed from the chamber or tower, for cooling.
Defendant, TA Foods Ltd. (Defendant) sells a roasted flax seed product under the brand name “NEPRI”. In 2016, Defendant purchased a used “micronizer”, to cook the oil seed used in its product. The micronizer was originally purchased from a company in United Kingdom and manufactured in 1994. The micronizer operates by subjecting oil seed to infrared radiation as the seed travels along a vibratory steel plate under a series of heated ceramic tiles. In the Defendant’s process, the oil seed is heated to temperatures ranging from 30-90°C for about 71 seconds. From the vibrating steel plate, the oil seed exits the micronizer down a slide into a triangular shaped hopper. The hopper is made of steel plating and uninsulated. From the bottom of the hopper, the seed travels up an uninsulated auger trough to an uninsulated cooling tower made of steel sheeting. The seed falls to the bottom of the cooling tower and is immediately transported from the cooling tower to other uninsulated hoppers made of steel sheeting for long-term storage or packaging. The retention time is less than 5 seconds. The Defendant does not have any other equipment or use any other process to cook oil seed.
The Plaintiff first learned of Defendant’s “NEPRI” products at a trade conference in Saskatoon on August 28, 2018 and subsequently noticed advertising for the product on its website. The parties attempted to arrange a mutually agreeable inspection of the Defendant’s manufacturing facility to allow the Plaintiff to assess potential infringement of the ‘376 patent. When talks broke down, the Plaintiff sued the Defendant for infringement. Specifically, a Statement of Claim was issued on December 17, 2018 and served on the Defendant on January 17, 2019. The Defendant filed a Statement of Defence dated April 18, 2019. On April 26, 2019, Defendant filed a Summary Judgement Motion.
In support of its Summary Judgement Motion, Defendant relied on both the Canadian prosecution history and the prosecution history of the corresponding U.S. Patent application 11/576,405 (the ‘405 application). Specifically, Defendant argued that the prosecution history of the ‘405 application established that the phrases “stream of air” and “insulated roasting chamber or tower” limitations were added to overcome prior art cited by the U.S. Patent and Trademark Office (USPTO). According to the Defendant, because the Plaintiff amended its claims to substantially mirror the method claims filed in the USPTO in order to overcome similar novelty and obviousness objections, the prosecution history of the ‘405 application should be admitted into evidence.
The Court noted that the language of section 53.1 made no reference to the use of prosecution histories from jurisdictions other than Canada. In fact, the Court noted that representations made by a patentee during the prosecution of a foreign patent application should, absent extraordinary circumstances, remain inadmissible for purposes of construing the terms used in Canadian patents. The Court worried that opening foreign prosecution file histories for purposes of Canadian claim construction would be to open the proverbial “pandora’s box”.
The Court found that extraordinary circumstances existed under the facts of this case. Specifically, the court stated:
 […] I find that the patentee specifically referred to the corresponding US Application prosecution history and acknowledged that the amendments to the claims in the ‘376 file history were made to overcome novelty and obviousness concerns as raised in the US Application prosecution history. Accordingly, the Court may look at the US Application prosecution history as part of a purposive construction of the claims of the ‘376 Patent.
 Asking the Court to ignore the patentee’s reference to the United States prosecution and claims in these circumstances amounts to inviting the Court to refrain from purposively construing the claims in the ‘376 Patent. Since the introduction of section 53.1, purposive construction requires consideration of not only the claims and the disclosure, but also the substance behind intentional amendments to the claims issued in Canadian patents. Ignoring the reference to the United States prosecution history and the restrictions made to claims to overcome novelty and obviousness objections that were then incorporated into the Canadian claims during prosecution would emasculate the intent and effect of section 53.1.
 Further, if the Court were to ignore consideration of the prosecution history of the corresponding US Application in circumstances such as are present here, patent applicants in Canada would be incentivized to intentionally refrain from being transparent with the Canadian Patent Office as to why amendments were made to limit claims during prosecution. If section 53.1 were interpreted to never allow consideration of foreign prosecution histories where limitations were specifically added to overcome novelty and obviousness objections and those limitations were subsequently adopted in the prosecution of the corresponding Canadian claims, applicants could rely on co-pending foreign applications to effectively avoid any application of section 53.1.
The Court stated that the two key elements of claim 1 at issue were:
- Heating oil seed “in a steam of air”; and
- Transferring the heated oil seed into an “insulated or partially insulated roasting chamber or tower” and maintaining the oil seed therein.
The Court found that during prosecution that the Plaintiff introduced both the “stream of air” and “insulated or partially insulated roasting chamber or tower” limitations into claim 1 and thus found that section 53.1 was applicable. Specifically, the Court referred to a letter to the Canadian Patent Office (CPO) dated August 24, 2012, where the Plaintiff admitted that the “newly submitted claims are much narrower in scope than the previously examined claims in view of the introduction of significant limitations derived from the description and previous dependent claims.” Additionally, the new claims were submitted “to encompass both novel and non-obvious subject matter.” Thus, according to the Court, this communication with the CPO was clear evidence of the inventor’s express intention that these two elements were were introduced to advance novel and non-obvious subject matter were essential.
With respect to heating in a “stream of air”, the Court stated that this was an essential element of claim 1 based on a clear reading of the claim itself, the specification of the ‘376 patent, and the prosecution history. Specifically, the Court noted that the specification of the ‘376 patent stated on page 6, lines 29-31 that “[A]ny heating system may be used to heat the flax seed to a desired temperature, providing this can be done fairly rapidly in accordance with the methods of the exemplary embodiments.” (emphasis added). The exemplary embodiments were described in the specification on page 6, lines 22-27 as, “[A]llowing heated air to circulate around the intersperse between the flax seed, effectively to cause the flax seed to achieve a ‘suspended in air’ state. In this way, the entire surface area of each flax seed will be substantially uniformly exposed to the heating temperatures.” Therefore, according to the Court, in a purposive construction, heating oil seed in a “stream of air”, means that the oil seed is subject to a stream of air to effectively achieve a suspended in air state such that the entire surface area of each flax seed was substantially uniformly exposed to the heating temperatures.
The Court found that the only process the Defendant used to roast its flax seed was a micronizer. The flax seed was subjected to infrared radiation as it traveled along a vibratory steel plate under a series of heated ceramic tiles. According to the Court, the flax seed was not subject to a stream of air. The Plaintiff countered by arguing that the scope of claim 1 was not limited to any particular type or source of heating and that the use of infrared radiation could potentially infringe claim 1. The Court stated that scope of claim 1 was limited to exclude heading by infrared radiation in the absence of a stream of air. Specifically, the Court stated that “[A]sking the Court for a broadened construction of Claim 1 is not supported by the specific language of Claim 1, the ‘376 disclosure, or the prosecution history.” Because the only process used by the Defendant did not heat oil seed in a stream of air, it did not include an essential element of claim 1.
With respect to the element “insulated or partially insulated roasting chamber or tower”, the Court noted that in the Defendant’s process that the oil seed exited the micronizer down a slide into a triangular shaped hopper. The hopper was made of steel plating and was uninsulated. From the bottom of the hopper, the seed traveled up an uninsulated auger trough to an uninsulated cooling tower made of steel sheeting. The seed then fell to the bottom of the cooling tower, and was immediately transported from the cooling tower to other uninsulated hoppers made of steel sheeting for long-term storage or packing. The retention time in the cooling tower was less than 5 seconds.
The Plaintiff argued that summary judgement was not appropriate based on this element because further investigation was needed to determine whether the auger trough or cooling tower could constitute an “insulated or partially insulated roasting chamber or tower.” The Court rejected this argument. Specifically, the Court noted that the use of “insulated or partially insulated” required the roasting tower to be insulated and the specification stated that during the maintaining step the flax seed was retained at a suitable temperature for completing or at least substantially completing the roasting of the flax seed. The evidence submitted by the Defendant demonstrated that the hoppers and cooling tower were made of thin gauge steel sheeting and were uninsulated.
Because two essential elements of claim 1, namely heating oil seed “in a stream of air” and an “insulated or partially insulated roasting chamber or tower,” were not included in the Defendant’s flax roasting process, the Defendant did not infringe claim 1 (or any of the other claims) of the ‘376 patent. The Court granted the Defendant’s Summary Judgement motion.
This post was written by Lisa Mueller.
 Canmar Foods Ltd v TA Foods Ltd, 2019 FC 1233 at paras 70-72.