In Canmar Foods Ltd v TA Foods Ltd,
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
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
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
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
- 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.
Foods Ltd v TA Foods Ltd, 2019 FC 1233 at paras 70-72.