Purpose of s 53.1 Explained

Bauer Hockey Ltd v Sport Maska Inc (CCM Hockey) 2021 FCA 166 Locke JA: de Montigny, Rivoalen JJA affg 2020 FC 624 Grammond J

2,214,748 / FC Prosecution History

In this decision, the FCA affirmed Grammond J’s holding that the claims at issue were obvious, essentially on the basis of the deferential standard of review applicable to conclusions of mixed fact and law [16]. The most important aspect of the decision are Locke JA’s obiter comments on the interpretation of s 53.1 regarding the use of prosecution history. He provide a succinct analysis of purpose of the provision which will no doubt inform its interpretation in future cases.

In the decision under appeal, Grammond J held that no valid claims of Bauer’s 748 patent were infringed. The invention at issue relates to hockey skates. The uppers were traditionally made with two “quarters” that were sewn together. The 748 patent essentially claimed a one-piece quarter. It may seem obvious that the two pieces should be joined together, and this is exactly what Grammond J held [FC 154-58], [FC 184]. Grammond J addressed the “Beloit question,” [FC 146], referring to Beloit (1986), 8 CPR (3d) 289 (FCA) 295, to the effect of “If it was so easy, why was it not done before?” His answer was that one-piece quarters were expensive when implemented with directional material, such as leather, and became commercially feasible with the development of non-directional skate materials [FC 162–64]. The FCA affirmed, essentially on the basis of the deferential standard of review applicable to conclusions of mixed fact and law [16].

Locke JA noted that Grammond J began his discussion of obviousness by referring to the Sanofi 2008 SCC 61 [67] framework. Locke JA remarked (citations omitted):

[6] The Federal Court further noted, and I agree, that this framework should not be applied in a rigid manner. The only mandatory considerations are those laid out in section 28.3 of the Patent Act, which is concerned with obviousness to a person skilled in the art or science to which the invention pertains, having regard to “information disclosed before the [relevant date] in such a manner that the information became available to the public in Canada or elsewhere.”

The Sanofi framework has proven to be contentious and even unhelpful in some cases, particularly at the step of either identifying the inventive concept or construing the claims—see here, here and here—and this remark by Locke JA might be seen as the FCA starting to step back from reliance on the Sanofi framework. But I wouldn’t read too much into this statement, as the Sanofi framework has never been considered mandatory, and this was a case in which identification of the inventive concept was easy, so that whatever guidance might be provided by that framework is less significant.

On another point of passing interest, Bauer made the novel argument that “where inferences from findings of fact involve an evaluation of numerous factors (as with obviousness), intervention by an appellate court may be more appropriate in cases where the fact-finding judge is inexperienced” [17], relying on Actavis v ICOS [2019] UKSC 15 [78]–[79], where the UKSC stated (my emphasis) “Where inferences from findings of primary fact involve an evaluation of numerous factors, the appropriateness of an intervention by an appellate court will depend on variables including the nature of the evaluation, the standing and experience of the fact-finding judge or tribunal, and the extent to which the judge or tribunal had to assess oral evidence.” Bauer argued that less deference should be given to Grammond J’s inferences of fact because he had only previously been involved in one other patent infringement case [17].

Locke JA rejected this argument, noting that “To set the degree of appellate intervention based on the experience of the judge at first instance would require an appeal court to consider the judge’s background on every appeal. This would result in standards of review in a spectrum, rather than the two standards defined in Housen” [18]. Locke JA also noted that Actavis could be distinguished, as “Bauer proposes reduced deference in the case of a judge with limited experience, whereas Actavis was suggesting increased deference in the case of a judge with considerable experience” [19, original emphasis]. That is true, but it seems to me that giving relatively more deference to an experienced judge necessarily requires giving relatively less deference to an inexperienced judge; while Bauer’s argument is remarkable, but it does have a basis in Actavis. Accordingly, Locke JA did not rely on that distinction, but instead indicated that he would not be inclined to follow Actavis on this point: “In any case, I see no reason to modify the tools the Court already has to address decisions under appeal.” He noted that functionally, “[t]he advantages the judge at first instance has regarding assessment of factually-suffused issues, which prompted the Supreme Court in Housen to adopt a deferential standard, apply even to inexperienced judges” [19]. This strikes me as an entirely compelling point. I’d also note that following the Actavis line of reasoning leads to a morass. Not all appellate judges are experienced in patent litigation, so we might have four standards based whether the appellate judges are or are not experienced and whether the trial judge is or is not experienced.

Finally, the most important aspects of the decision relate to the interpretation of s 53.1 regarding the use of prosecution history. Grammond J had held that

[65] When an issue of claims construction arises, the patentee is always making representations to the Court as to the proper construction of the claims and the defendant is always attempting to rebut those representations. Therefore, in my view, as long as the issue is one of claims construction, section 53.1 applies and the prosecution history is admissible. In other words, there is no need to identify a particular representation and rebuttal every time a reference is made to the prosecution history. It is simply integrated in the interpretive process.

As Locke JA noted, “[t]his interpretation seems to open the door to unrestricted reference to the prosecution history to assist with claim construction,” and as such it is at odds with the text of the provision:

Subsection 53.1(1) is a detailed provision that contemplates admitting into evidence certain portions of a patent’s prosecution history for a certain purpose: “to rebut any representation made by the patentee in the action or proceeding as to the construction of a claim in the patent.” If this provision had been intended simply to brush aside the general prohibition against reliance on a patent’s prosecution history for the purposes of claim construction, it could have been much shorter.

This is not simply a textual point. The purpose of of s 53.1 “is to provide a tool to use against patentees who take one position concerning the meaning of a claim during prosecution of a patent application and another during litigation on the resulting patent. Accordingly, the concern relates to inconsistent statements” [37] (my emphasis). This limited purpose makes sense. On the one hand, it is particularly objectionable when the patentee wants to have it both ways, advancing a narrow interpretation during prosecution to obtain the patent, and then advancing a broad interpretation during litigation to expand the scope of its monopoly. On the other hand, permitting the general use of prosecution history, raises problems relating to “the public notice function of patent claims and the potential for inappropriately complicating litigation” [39], that were identified by the SCC in Free World 2000 SCC 66 [66] as reasons for refusing to allow the use of prosecution history for claim construction. Even though the legislature has now permitted some use of prosecution history, those concerns remain valid. The need to balance these considerations provides a purposive rationale for the limited nature of the exception, and that purpose is consistent with a straightforward reading of the text. While the legislature might reasonably have balanced these considerations differently, “it is not the role of the courts to participate in such a debate. Rather, we interpret and apply the legislation as written” [39].

Locke JA also noted that Grammond J’s interpretation seems to be inconsistent with the prior FC caselaw on s 53.1, specifically referring to Canmar 2019 FC 1233 affd 2021 FCA 7 (see here) and Lilly v Apotex 2020 FC 814. The interesting point here is that Locke JA did not refer to the decision of Crampton CJ in Allergan v Sandoz 2020 FC 1189, which, as discussed here, identified what appears to be a truck size loophole that is based squarely in the text of the provision. Crampton CJ’s decision certainly supports the point being made by Locke JA, namely that the exception is a limited one, and the text of the Act must prevail when it is clear. So the fact that Locke JA chose not to cite Allergan v Sandoz, while citing other FC caselaw, namely Lilly v Apotex, suggests to me that he did not want to be seen as approving Crampton CJ’s interpretation. I don’t take this as suggesting that Locke JA necessarily disagrees with Crampton CJ’s interpretation, but only that, given the magnitude of the loophole that Crampton CJ identified, the issue is best addressed by the FCA after the point is directly raised and argued, rather than by approving the decision in obiter comments.

Limits on Use of Foreign Prosecution History

Canmar Foods Ltd v TA Foods Ltd 2021 FCA 7 de Montigny JA: Pelletier JA, Rivoalen JJA affg 2019 FC 1233 Manson J

            2,582,376 / method for roasting oil seed

Yesterday’s post the summary judgment aspects of the Canmar appeal; this post turns to the issue of s 53.1, which permits the use of prosecution history to aid in claim construction in certain circumstances. Justice Manson’s decision at first instance was the first to interpret s 53.1, and a difficult issue was raised right off the bat. The defendant, TA Foods, wanted to refer to the US prosecution history, while s 53.1 on its face only permits use of communications between the patentee and “an officer or employee of the Patent Office”—which is to say, the Canadian prosecution history. As discussed here, Manson J held that foreign prosecution history should be admissible to aid in a construction of Canadian claims only in “extraordinary circumstances” [73], [74], [77]. In general, this means that “prosecution of the foreign application is made part of the prosecution history of the Canadian patent” [77, original emphasis]. While Manson J did consider the foreign prosecution history [85]–[90], he expressly stated that he would have come to the same conclusion in any event [79].

Justice de Montigny ultimately held that Manson J should not have referred to the foreign prosecution history on the facts in this case [77]. The FCA’s restrictive approach to the use of foreign prosecution history reflects the text of s 53.1, but at this point we cannot rule out the possibility that foreign prosecution history might be admissible if made part of the Canadian prosecution history with sufficient particularity. That is a question “left for another day” [74], and de Montigny JA emphasized that “I wish to express no firm views on the matter” [77].

More generally, de Montigny JA’s decision for the FCA provides a useful discussion of a number of issues, but ultimately refrained from deciding most of them, on the view that “courts [should] refrain from deciding beyond what is strictly necessary for the resolution of the case of which they are seized” [74]. In my view this is a salutary principle—I often wish the SCC would pay more heed to it. The result is that the decision illuminates the FCA’s thinking on this issue, while leaving the specifics to be developed in future cases that raise them more directly. This is the way the law should develop.

Value of foreign jurisprudence

Justice de Montigny noted that s 53.1 appeared to respond in part to disquiet expressed in some FC decisions about always excluding consideration of prosecution history, especially in some particularly egregious cases [51]–[53], and he also noted that “it can also be perceived as a step to better align Canadian law with its British and American counterparts” [53]. That is true in broad strokes—as de Montigny JA noted, US law of course has a well-developed doctrine of prosecution history estoppel [54]–[56], and even the UK has made some steps in that direction [57]–[62]. With that said, I do not see this as an invitation to draw detailed guidance from US or UK law (which are very different from each other), as de Montigny JA noted that s 53.1 “is carefully tailored, and it would go against statutory interpretation principles to try to go beyond its original intent” [70]. Our law relating to prosecution history will therefore turn on the interpretation s 53.1.

Need there be a specific representation?

Part of that careful tailoring is that prosecution history may be admitted “to rebut any representation” made by the patentee in the action. Justice de Montigny noted that a question has arisen as to whether there must be some specific representation as to the construction of the claim [65], or whether the emphasis “is not so much on the rebuttal of a particular representation, but rather on the interpretive process itself,” as suggested in Bauer Hockey 2020 FC 624 (discussed here): [66]. Justice de Montigny left this question for another day, as it was not necessary to decide the case at hand [67]. My impression is that he was leaning to the latter interpretation, but I can’t point to anything specific in the reasons to support that view, and in any event he expressly left the matter open.

Foreign prosecution history

The main issue raised on the facts was the use of foreign prosecution history. Justice de Montigny emphasized the need to adhere to the text of the provision [70], which suggests a very limited role, if any, for foreign prosecution history. Further, he noted that “There are also public policy reasons for treading carefully in allowing extrinsic evidence” [70]. Allowing foreign patent prosecution history into the analysis “might lead to overly contentious and expensive litigation,” given different law, differences in language potentially requiring translation, and differences in the registration system. He noted that “in this case, the patent application in the United States was eventually dropped, while registration in Canada was completed” [71]. Thus both textual and purposive considerations support a restrictive approach to the use of foreign prosecution history. At the same time he acknowledged the force of the argument for “keeping those who have previously disclaimed elements from their patent from re-claiming them in future infringement cases,” both in general [72] and on the facts of this case [73].

In this case, Manson J held that foreign prosecution history would be admissible in “extraordinary circumstances” [FC 73, 74, 77]. As noted above, Manson J described such circumstances as being where “that prosecution of the foreign application is made part of the prosecution history of the Canadian patent” [FC 77, original emphasis]; Canmar referred to this as an “incorporation by reference” theory [69]. On the facts of the case, “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” [FC 70], [68].

Justice de Montigny did not dismiss the possibility that some form of incorporation by reference doctrine might permit foreign prosecution history to be used under s 53.1, but he left this question “for another day,” as he was of the view that the facts at hand “do not lend themselves to a proper finding of incorporation by reference” [74]. Justice de Montigny noted that “There is nothing in the prosecution file of the ‘376 Patent that identifies with any detailed particularity what specific ‘written communication’ from the US prosecution history is incorporated and where that written communication can be found” [75]. The only mention is a response to the Examiner stating that the new claims correspond to those submitted during prosecution “of a related United States application” [75], and he remarked that “It is a stretch to say that the prosecution of the US Application is incorporated by reference when the specific application is not even cited within the document” [76]. There is some suggestion in the decision that US doctrine of incorporation by reference might provide some guidance [76], though it remains to be seen how influential this will be, as the matter will ultimately turn on the interpretation of s 53.1.

The FCA decision in Canmar therefore establishes that the foreign prosecution history cannot be used unless the Canadian prosecution history contains some fairly specific reference to the foreign prosecution history. It should be emphasized, however, that the converse is not necessarily true: this does not mean that the foreign prosecution history will be considered if there is a sufficiently specific reference in the Canadian file. Whether foreign prosecution history will be admissible at all, and if so, exactly what kind of reference is needed, is a question left for another day [74[.

In my view the FCA was entirely right to confine itself to the holding necessary to dispose of the appeal, while leaving other questions for another day. Section 53.1 is novel—it does not appear to reflect any particular foreign jurisprudence—and it is detailed. Accordingly it will be best for the law to develop incrementally, at least for a period as we get a better understanding of the issues that will be raised by s 53.1 in different factual contexts.

Prosecution History May Not Be Used to Rebut Representations Made by a Licensee

Allergan Inc v Sandoz Canada Inc 2020 FC 1189 Crampton CJ

2,507,002 / silodosin / RAPAFLO / NOC

Section 53.1 of the Patent Act permits the use of prosecution history in claim construction in certain circumstances. In this decision, Crampton CJ held that s 53.1 only permits use of prosecution history to rebut a representation made in litigation by a patentee, not representations made by a licensee. This is a truck-sized loophole in s 53.1, and Crampton CJ noted the prosecution history in question “provides a glaring example of the mischief that is implicitly permitted by the current wording” [135]. Nonetheless, Crampton CJ’s analysis of the provision is entirely compelling.

As noted in Monday’s post, the key issue on infringement was whether “wet granulation” was an essential element of the claims in question. Allergan argued it was not. Sandoz wished to rely on representations made during patent prosecution to rebut this assertion. The difficulty is that s 53.1 permits prosecution history to be introduced to rebut any representation “made by the patentee in the action.” Allergan is not the patentee; it is the exclusive Canadian licensee [1] and is the “first person” under the PM(NOC) Regulations [5]. The patent owner is Kissei Pharmaceutical and the patent was prosecuted on Kissei’s behalf [1], [3]. Kissei was also a defendant to this NOC action, joined pursuant to s 6(2), but crucially, Kissei took no position on the infringement issue, though it adopted Allergan's submissions relating to validity. (Kissei did not appear during the trial [7].)

So, Allergan’s argument was that the prosecution history could not be introduced because it can only be used to rebut a representation by the “patentee” and the patentee, Kissei had not made any representations. The question facing Crampton CJ was therefore whether s 53.1 should be interpreted to allow prosecution history to be used to rebut representations made by a licensee.

As noted, I find Crampton CJ’s reasons on this point to entirely convincing. I don’t have anything to add, so I will simply reproduce the key passage (with some references omitted):

[124] In my view, none of the arguments advanced by Sandoz can overcome the plain wording of subsection 53.1(1), a contextual reading of the Act or the jurisprudence in respect of the definition of the word “patentee” in section 2 of that legislation.

[125] It is trite law that “the words of a statute must be read ‘in their entire context and in their grammatical and ordinary sense harmoniously with the scheme of the Act, the object of the Act, and the intention of Parliament’”.

[126] The “chapeau” in subsection 53.1(1) plainly limits the scope of that provision to permitting certain written communications to be admitted into evidence to rebut any representation made by the patentee in an action or proceeding, in respect of the construction of a claim in a patent that is at issue in the action or proceeding. In the present proceeding, it is admitted that the patentee is the defendant Kissei, which has not made any representation to the Court with respect to the construction of the ‘002 Patent. Accordingly, in the absence of any clear indication elsewhere within the scheme or object of the Act that Parliament intended to word “patentee” to include a licensee of a patent, subsection 53.1(1) cannot be invoked in this proceeding.

[127] I do not agree with Sandoz’s position that a licensee falls within the meaning of the word “patentee”, as defined in section 2 of the Act, namely, “the person for the time being entitled to the benefit of a patent”. This position was specifically considered and rejected in Electric Chain Co of Canadas Ltd v Art Metal Works Inc, [1933] SCR 581 at 586-587 [Electric Chain]. The effect of that decision was that a licensee had no right to be a party to an infringement action in Canada. As a result, what is subsection 55(1) was added to the Act: American Cyanamid Co v Novopharm, [1972] FC 739 at paras 23-24 (FCA) [American Cyanamid]. That provision, which has undergone some minor amendments that are not germane for the present purposes, states:

“A person who infringes a patent is liable to the patentee and to all persons claiming under the patentee for all damage sustained by the patentee or by any such person, after the grant of the patent, by reason of the infringement.”

[128] It has since been confirmed that a person who is a licensee under a patent is a “person claiming under” the patentee within the meaning of subsection 55(1): Armstrong Cork Canada v Domco Industries Ltd, [1982] 1 SCR 907 at 914; American Cyanamid, above, at paras 31-32.

[129] What is instructive for the present purposes is that while the Act was amended to permit a licensee to sue for infringement, the definition of “patentee” was not amended following the interpretation that it was given in Electric Chain, above.

[130] Moreover, given that Parliament included the words “the applicant for a patent” in clause 53.1(1)(b)(i), but not in the “chapeau” of subsection 53.1(1), it can be inferred that (i) Parliament was aware of the distinction between a patentee and a person who is not the patentee, and (ii) Parliament decided to strictly limit the scope of the “chapeau” to a person who is a patentee.

[131] This interpretation of Parliament’s intent finds some support in the legislative history. In particular, in the submission that IPIC made to the [Senate Banking, Trade and Commerce Committee], discussed at paragraph 123 above, IPIC noted that the language of section 53.1 created a “loophole” that would permit “a patentee to circumvent the operation of this section by acting through a licensee”: IPIC Submission, above, at 12. To address this “loophole”, IPIC recommended that subsection 53.1(1) be amended to include “persons claiming under the patentee”. The specific amendment proposed by IPIC is the underlined wording in the chapeau of that provision:

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 or a person claiming under the patentee in the action or proceeding as to the construction of a claim in the patent if […]

[132] Ultimately, IPIC’s recommendation was not accepted, and Bill C-86 was passed without any change to the language of subsection 53.1(1). This legislative history provides additional support for the view that, at the time Parliament added subsection 53.1(1) to the Act, it was aware of the distinction between a patentee and a person who is not a patentee, yet it chose to limit the scope of section 53.1 to representations made by patentees.

While Crampton CJ did not rely primarily on the last point, I must say that I find it particularly compelling; this very issue was before the responsible Parliamentary committee, along with a very simple fix, and it was not implemented. The inference that it was considered and rejected is strong, which implies that the “loophole” was specifically intended.

[133] In summary, the plain and ordinary meaning of the language in subsection 53.1(1), together with a contextual reading of the Act and the jurisprudence discussed above, support the view that the word “patentee” in subsection 53.1(1) does not include a licensee. The legislative history also provides some additional support for this interpretation. Sandoz has not identified any contextual consideration to support the alternative interpretation that it has advanced.

While the considerations reviewed by Crampton CJ are textual and contextual, rather than purposive, and there is evidently some kind of purposive argument to be made that this loophole frustrates the operation of the provision, Crampton CJ’s textual and contextual analysis is so entirely compelling that I cannot see that any other conclusion would be possible without an impermissible usurpation of the legislative role.

Sandoz also argued that the prosecution history was admissible entirely apart from s 53.1, relying on the FC decision in Distrimedic 2013 FC 1043 at [210]: [116]. Crampton CJ rejected this argument, in part on the basis that Distrimedic is distinguishable [117]. More importantly Crampton CJ also observed that in light of the bar on the use of prosecution history set out in of Free World 2000 SCC 66 [66], Distrimedic has been “overcome” by the enactment of section 53.1 [115], [118]. I understand Crampton CJ to be saying that the use of prosecution history is now confined to the circumstances set out in s 53.1. This strikes me as undoubtedly correct. Any use of prosecution history in Canada now turns entirely on the interpretation of s 53.1 and any subsequent legislative amendments.

Crampton CJ therefore concluded that “given that no representation has been made by the patentee (Kissei) of the ‘002 Patent in the present action, the file prosecution history is not admissible in evidence in this action. It is barred by the prohibition against extrinsic evidence: Free World, above, at para 66" [133].

Crampton CJ’s holding was driven inexorably by the legislation; he did not necessarily welcome it. On the contrary, he observed “in passing,” that the “file prosecution history in question provides a glaring example of the mischief that is implicitly permitted by the current wording of subsection 53.1(1)” [135]. For those interested in looking at the prosecution history themselves, the documents 02507002 - 2011-08-25 - PRO and 02507002 - 2011-01-19 - PRO emphasize wet granulation to overcome various objections.

"Foreign Prosecution History Is Inadmissible"

Gemak v Jempak 2020 FC 644 Lafrenière J

            2,276,428 / 2,337,069

After a decade in which it was almost unheard of for the Federal Court to grant a contested motion for summary trial or summary judgment in a patent case, it seems they are now raining down upon us, with Lafrenière J’s summary judgment decision in Gemak v Jempak following Manson J’s decisions in Viiv v Gilead 2020 FC 486 (here) and Canmar 2019 FC 1233 (here). Lafrenière J’s decision in this case is a good example of summary judgment being used to dispose expeditiously of a far-fetched claim construction argument. It is also notable for holding expressly that foreign prosecution history is not admissible under s 53.1. This is in tension with Manson J’s holding in Canmar that foreign prosecution history should be admissible, albeit only in “extraordinary circumstances” [73], [74], [77].

Gemak’s 428 patent at issue was to a dishwasher detergent pod. These pods commonly use percarbonate as a bleaching agent which is activated on exposure to water. Percarbonate is susceptible to degradation by contact with other detergent ingredients or by moisture. For that reason, the percarbonate must be coated to protect it prior to actual use of the pod. Claim 1 is representative [13]:

A detergent composition comprising a granulated percarbonate and a blend which encapsulates the percarbonate, the blend comprising . . . carboxymethyl cellulose [CMC]

Jempak’s detergent pods included percarbonate encapsulated in a protective coating. It was not really disputed that the use of CMC was an essential element of the claim [119]. It was also established that the protective coating used by Jempak did not comprise CMC. Gemak’s main argument was that CMC was present in the other detergent ingredients in Jempak’s pods, and that once the pod was assembled, the CMC in the other ingredients could adhere to the percarbonate coating, and that the resulting coating with CMC adhering to it would constitute “a blend” comprising CMC which encapsulates the percarbonate [121]. Lafrenière J rejected this on the view that “encapsulation refers to a protective coating (a blend) that is applied to the percarbonate during its manufacture to maintain the stability of the percarbonate and to prevent it from decomposing prematurely before use” [123]. Gemak’s position was not helped by its “evasive and defiant” expert witness [104].

It strikes me that this is an excellent example of the kind of argument that should not be allowed to proceed to a full trial. The patent system is rife with the potential for abuse, in large part due to the cost and complexity of patent litigation. The cost-effective disposition of weak claims is essential to ensuring that the patent system encourages innovation, rather than impeding it.

The other notable point is that Jampak sought to adduce evidence of the US prosecution history. Lafrenière J refused to allow this evidence, in part because it was introduced too late [77] and in part because it would not assist the court [78]. But he also held expressly that “foreign prosecution history is inadmissible” under the new s 53.1 of the Act: [86], and generally [82]-[86]. This holding was primarily based on a straightforward textual argument:

[83] Subsection 53.1(1) provides that the prosecution history may be admitted into evidence in an action to rebut any representation made by the patentee regarding claim construction, but only when specific conditions are met. In particular, subparagraph 53.1(1)(b)(ii) provides that the communication must be between the applicant and “the Commissioner, an officer or employee of the Patent Office or a member of a re-examination board.”

[84] The definition of “Commissioner” is set out in section 2 of the Patent Act as meaning the Commissioner of Patents, who is appointed by the Governor in Council and exercises the powers and performs the duties conferred and imposed on that officer by or pursuant to the Patent Act. The Patent Office described in section 3 as an office attached to the Department of Industry, or to such other department of the Government of Canada as may be determined by the Governor in Council.

Further,

[86] There is a further presumption against the legislature impliedly changing established law, particularly the common law. If Parliament had intended that communications prepared in respect of the prosecution of the application for a foreign patent could be admitted, clearer language would be required to effect that result. In the circumstances, I conclude that section 53.1 did not change the existing rule, as enunciated in Free World Trust, that foreign prosecution history is inadmissible.

I made some similar points in my blog post on Manson J’s decision in Canmar 2019 FC 1233 [77], which held that in “extraordinary” circumstances foreign prosecution history should be admissible to aid in construction of the Canadian claims.

On the other hand, “[t]he language of section 53.1 is limited to communications between the patentee and the Canadian Patent Office” [70]. In particular, per s 53.1(b)(ii), the communication must be between the applicant and “the Commissioner, an officer or employee of the Patent Office or a member of a re-examination board.”

Further, prior to the enactment of s 53.1, it was clear law that “statements made during prosecution of Canadian patent applications or corresponding foreign patent applications were neither relevant nor admissible with respect to construing terms used in issued Canadian patents” [58]; and Free World 2000 SCC 66 [66]. As a matter of statutory interpretation, “[i]t is presumed that the legislature does not intend to make any change in the existing law beyond that which is expressly stated in, or follows by necessary implication from, the language of the statute in question”: R v T (V) [1992] 1 SCR 749, quoting with approval Maxwell on the Interpretation of Statutes; and see also Parry Sound v OPSEU [2003] 2 SCR 157 [39]. This implies that s 53.1, in providing for admissibility of communications to the Canadian examiner, did not change the existing rule that foreign prosecution history is inadmissible.

I’d say that someone owes me a beer.

In any event, there is evidently some tension with Manson J’s holding in Canmar that foreign prosecution history should be admissible, albeit only in “extraordinary circumstances” [73], [74], [77]. Lafrenière J did not directly discuss Manson J’s holding on this point.

No Specific Prerequisites Before Having Recourse to Prosecution History in Claim Construction

Bauer Hockey Ltd. v. Sport Maska Inc. (CCM Hockey) 2020 FC 624 Grammond J

2,214,748

In this decision, Grammond J held that no valid claims of Bauer’s 748 patent were infringed. The decision turned largely on claim construction and Grammond J noted that if the parties had brought a motion for summary judgment or summary trial “a considerable amount of judicial resources would have been saved, and each party’s legal costs would have been substantially reduced” [29]. This indicates that Manson J is not alone among FC judges in seeing the need for increased use of summary proceedings: see Viiv Healthcare 2020 FC 486 (here) and Canmar 2019 FC 1233 (here). One noteworthy point is Grammond J’s holding that there are no specific requirements that must be triggered before reference to the prosecution history is permissible under s 53.1 [65].

The invention at issue relates to hockey skates. The uppers were traditionally made with two “quarters” that were sewn together. The 748 patent essentially claimed a one-piece quarter. It may seem obvious that the two pieces should be joined together, and this is exactly what Grammond J held [154-58] [184]. Grammond J addressed the “Beloit question” – 'If it was so easy, why was it not done before?' (my paraphrase of Beloit (1986), 8 CPR (3d) 289 (FCA) at 295, quoted at [146]), by noting that it had not been done before because of cost considerations and not because it was not technically feasible [162-65]. Bauer tried to rebut the prima facie obviousness case with arguments based on commercial success, but Grammond J rejected these, explaining that an adequate causal nexus between the commercial success and the invention specified by the claims had not been established [171-79].

On claim construction there has been an on-going debate as to whether recourse to the disclosure is always permissible, or is permissible only if the claim terms are ambiguous. Grammond J came down very firmly in favour of the former position:

[49] Legal interpretation is not an obscure practice governed by arcane rules. It is, as Lord Hoffmann once famously said, not very different from “the common sense principles by which any serious utterance would be interpreted in ordinary life.”

[55] The modern method [of interpretation] aims at helping the interpreter find clues about the meaning of a legal writing. There is no hierarchy of these clues, nor any predetermined order in which they are considered. In particular, the modern method rejects what is known as the “plain meaning rule,” or the idea that if one category of clues – the text – provides a “clear” answer, the other categories of clues are to be disregarded.

He noted that “Most recent decisions of the Federal Court of Appeal are in line with this approach,” [57], quoting Tetra Tech 2019 FCA 203 [86] and Tearlab 2019 FCA 179 [33] saying that “[c]laim construction requires that the disclosure and the claims be looked at as a whole.” I am entirely in agreement with Grammond J’s observations in this regard.

Without detracting from this general approach, Grammond J noted that patents have “certain distinctive characteristics” that need to be taken into account [51]. One in particular is reference to the prosecution history under s 53.1 which provides that communications between the patentee and the Patent Office “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.” In the specific of the modern approach to interpretation, Grammond J held that there are no specific requirements that must be triggered before reference to the prosecution history is permissible (emphasis added):

[65] Although the use of prosecution history is described in terms of estoppel in the United States, section 53.1 squarely makes this a matter of claims construction. When an issue of claims construction arises, the patentee is always making representations to the Court as to the proper construction of the claims and the defendant is always attempting to rebut those representations. Therefore, in my view, as long as the issue is one of claims construction, section 53.1 applies and the prosecution history is admissible. In other words, there is no need to identify a particular representation and rebuttal every time a reference is made to the prosecution history. It is simply integrated in the interpretive process.

Grammond J did have recourse to the prosecution history, but it served only to confirm the interpretation that was plain from the patent itself. This is not very surprising; the examiner made an obviousness objection, the applicant amended the claims to overcome it, and in litigation the patentee sought to reclaim the lost ground [103-06]. This illustrates why recourse to the prosecution history is often likely to be redundant: when the examiner accepts an amendment intended to restrict the scope of the claims, it will not be very surprising that the new language does indeed restrict the scope of the claims.

Prosecution History and Summary Judgment

Canmar Foods Ltd v TA Foods Ltd 2019 FC 1233 Manson J
            2,582,376 / method for roasting oil seed

Canmar is the first case to invoke the new s 53.1, which provides that the prosecution history may be used in an action to rebut any representation made by the patentee regarding claim construction. As importantly, it is one of the first patent cases in many years to grant summary judgment on non-infringement / invalidity.

My previous post on Canmar discussed Manson J’s holding that foreign prosecution history may, in some conditions, be considered pursuant to s 53.1. I argued that despite this holding, Manson J did not actually consider the US prosecution history. He undoubtedly did consider the Canadian prosecution history, and moreover, he considered it in order to dispose of the action by way of summary judgment. In this post I will suggest that Manson J used summary judgment in order to side-step the restrictive approach to summary judgment that seems to have prevailed in patent cases for some time. The key claim construction question at issue is one that would often call for expert evidence, but invoking prosecution history turned the issue into a matter of law instead. In effect, Manson J solved a problem in the law relating to summary judgment by invoking prosecution history. The difficulty is that if indeed there is a problem with an overly restrictive approach to summary judgment, prosecution history is not a cure; it will work in only cases where the key prior art was the subject of an objection, and not where the applicant had drafted around it from the outset. Moreover, it is always risky to try leveraging one area of the law to fix a defect in another area, as that will often lead to law that is deficient in both areas.

Foreign Prosecution History Admissible under S 53.1 — or Is It?

Canmar Foods Ltd v TA Foods Ltd 2019 FC 1233 Manson J
            2,582,376 / method for roasting oil seed

Canmar is the first decision of the Federal Court to interpret and apply the new s 53.1, which provides that the prosecution history may be admitted into evidence in an action to rebut any representation made by the patentee regarding claim construction. The defendant, TA Foods, argued that key limitations in the claims were added to overcome prior art cited by the USPTO [57]. A central issue in the case was therefore whether foreign prosecution history falls within the scope of s 53.1 [69]. This is a very important issue because Canada is typically a jurisdiction of second filing and, as Manson J noted, “Prosecution of Canadian patents often follows prosecution of corresponding patent applications in other jurisdictions” [73].

Manson J held that under certain circumstances, the foreign prosecution history should be admissible to aid in construction of the Canadian claims [77], though his holding on this point was expressly obiter, in that he stated that he would have found there to be no infringement “[r]egardless of the US Application prosecution history” [79]. In this post, I suggest that Manson J’s holding puts significant strain on the text of s 53.1. I also point out that not only was his holding technically obiter, it was substantively obiter, in that Manson J did not rely on the US prosecution history at all in his analysis on the facts. This will no doubt diminish the precedential value of this holding.

Bill C-86 and the Use of Prosecution History in Claim Construction

Bill C-86 has introduced several proposed amendments to the Patent Act. The most problematic, in my view, is the proposed s 53.1 (introduced by s 191 of the Bill), which makes prosecution history relevant in claim construction. More specifically, the proposed s 53.1 provides a statutory definition of communications constituting the prosecution history, and provides that such communications “may be admitted into evidence to rebut any representation made by the patentee in the action . . . as to the construction of a claim in the patent.” (Section 187 of the Bill has an apparently related amendment to s 10(1) which would make the file history available to the public when the patent is laid open; and s 197 of the Bill introduces a new s 123.1 which provides that the same principle applies in respect of a certificate of supplementary protection.)

The proposed s 53.1 raises two questions: What is the intended effect? Is the change desirable? One might have thought that the effect of an amendment would be clear, and the difficult question is whether it is sound as a matter of policy. But s 53.1 is not entirely transparent, in part because “representation” is neither a term of art, nor even a commonly used term, in patent law. In Canadian law, at least at present, claim construction is an inquiry as to how a person of ordinary skill in the relevant art (the POSITA) would understand the claim, in light of the relevant context. The relevant context includes things such as the common general knowledge of a person skilled in the art, but not, under current law, the prosecution history. The relevant context is established on the basis of evidence, such as expert witnesses or textbooks. With the context established, the parties make submissions to the court (aka arguments) based on this evidence, as to how the POSITA would understand the claim. Does “any representation” in the proposed amendment refer to the evidence, or the arguments? And what would it mean to “rebut” a representation? Consider the parallel with the question of using legislative history in statutory interpretation – a patent is deemed to be a regulation by s 2(1) of the Interpretation Act, claim construction is like interpreting the statute (Whirlpool 2000 SCC 67 [49(e)]), and the prosecution history corresponds to the legislative history. Suppose that legislative history could not be used in statutory interpretation, and an amendment were made to the Interpretation Act saying that legislative history may be admitted into evidence to “rebut representations” made by a plaintiff in litigation as to the interpretation of the statute. What effect would that have?

Rather than trying to further parse the proposed s 53.1 directly, I will consider the various ways in which prosecution history is used in other legal systems which permit its use; whether s 53.1 might be understood as amending Canadian law analogously; and whether such a change would be desirable. (To emphasize the main points, I am overstating the distinction between these various approaches, which may run together at the margins.)

Is it Time to Revisit the Rule Against Using Extrinsic Evidence in Claim Construction?

Pollard Banknote Limited v BABN Technologies Corp 2016 FC 883 Locke J
            2,752,551

In this declaratory action brought by Pollard, Locke J declared both claims of the ‘551 patent, owned by Scientific Games (the successor to BABN), to be invalid (Claim 1 for obviousness 242], Claim 2 for ambiguity [144]). On the infringement counter-claim, he held that the claims were not infringed in any event [2]. The decision raises a number of interesting issues, perhaps the most of important of which relates to prosecution history estoppel.

The ‘551 patent relates to a security feature for instant lottery tickets. These tickets have a scratch-off layer covering the “game data” which the customer scratches off to reveal whether the ticket is a winner and the amount of any prize. (In cheaper tickets a paper pull-tab may be used to cover the prize instead of the scratch-off layer.) To prevent fraud, the tickets normally also have validation information, in the form of numbers and/or a bar code, which is checked against the lottery’s online system on redemption to confirm that the ticket had been legitimately sold, that it was indeed a winner, and that it had not previously been redeemed [12]. As additional security, the validation information may also be hidden by a scratch off layer. This was all part of the prior art.

More File Wrapper Estoppel in Canada

Eli Lilly Canada Inc. v. Mylan Pharmaceuticals ULC / tadalafil (NOC) 2015 FC 125 de Montigny J
            2,371,684 – tadalafil dosage form – CIALIS

The ‘684 patent was for tadalafil in a dosage form of less than 20mg, with separate claims to various specific dosage forms (eg “5. The dosage form of claim 3 comprising about 5 mg of the compound in unit dosage form”). A question arose as to whether a maximum daily dosage of 20mg should be considered to be an essential element of the claims [150]. de Montigny J rejected this argument, relying in part on the file history. The application originally filed with the Patent Office contained claims reciting the method of treating sexual dysfunction comprising administering about 1 to 20 mg tadalafil, up to a maximum total dose of 20 mg per day. These claims were rejected for claiming a method of medical treatment. In response, Lilly redrafted these claims as “use” claims and removed any reference to a maximum total dose per day [154]. Citing his own prior decision in Distrimedic 2013 FC 1043, [209-10], held that it was proper to use this file history in interpreting the claims:

[154] While the file history of a patent application is generally considered as extrinsic evidence and not admissible, I have already held that a change in the wording of a claim as a result of an objection from the Patent Office is an objective fact that can be considered and from which an inference may de drawn

This is notwithstanding the SCC’s insistence in Free World 2000 SCC 66 that in light of the objective nature of claim construction “To allow . . . extrinsic evidence [such as statements or admissions made in the course of patent prosecution] for the purpose of defining the monopoly would undermine the public notice function of the claims, and increase uncertainty as well as fuelling the already overheated engines of patent litigation” [66]. As I argued in my post on Distrimedic, de Montigny J is right to allow this use of the file history and the SCC is wrong. This Tadalafil Dosage Form decision provides another illustration of why it is wrong to allow a patentee to try to reclaim in litigation a limitation that it gave up in prosecution. As discussed here, the alternative approach to dealing with this kind of shifting position is to invoke s 53(1), potentially resulting in the invalidation of the entire patent. Patentees might prefer to embrace file wrapper estoppel.

Prosecution History Estoppel Meets Section 53

NOV Downhole Eurasia Limited v TLL Oil Field Consulting 2014 FC 889 Mosley J

            2,255,065

The pigeons are coming home to roost from the SCC’s ill-advised holding in Free World 2000 SCC 66, [66], that prosecution history is not to be used in claim construction (for my critique of the SCC decision, see here).

The invention at issue in NOV Eurasia v TLL Consulting is a downhole oilwell tool which comprises a valve. The defendant alleged that during patent prosecution the applicant had amended the application to restrict the claims to embodiments which included a transverse valve, and they now sought to assert the patent against the defendants even though the allegedly infringing tool does not have a transverse valve [9].

If we had a doctrine of prosecution history estoppel, this would be a straightforward matter. If indeed the applicant had given up the scope in question during prosecution, then the patentee would be estopped from reclaiming that scope in litigation, and the patent would be construed accordingly. The claim, and the patent, would remain valid, but the defendant’s tool (assuming it did not in fact contain a transverse valve), would not infringe. This is an eminently fair and sensible result.

But because the SCC in Free World held that prosecution history cannot be considered as a matter of claim construction, the defendant in this case pleaded that the applicant’s statements were made “with the intention of misleading the Patent Office,” and so the entire patent is void pursuant to s 53(1) [9], which provides that:

A patent is void if any material allegation in the petition of the applicant in respect of the patent is untrue, or if the specification and drawings contain more or less than is necessary for obtaining the end for which they purport to be made, and the omission or addition is wilfully made for the purpose of misleading.

The patentee in this case brought a motion to have the paragraphs pleading s 53 struck. Prothonotary Milczynski granted the motion, but Mosley J reversed, holding, after a review of the case law, that “[i]t remains a live issue whether section 53 of the Patent Act may void an entire patent due to steps taken in the application process” [32]. I think Mosley J is right on this point, but given the low threshold for allowing the pleading to stand I will not review the case law in detail.

The broader point is that the SCC’s Free World holding has created an unpalatable dilemma for the lower courts. If s 53 cannot be used in this manner, then a patentee may be able to narrow the scope of its claim during prosecution to obtain the patent and then try to reclaim that scope in subsequent litigation. On the other hand, if s 53 can be used, then what would have been a battle over claim construction turns into an atomic bomb of patent invalidity. This will increase uncertainty, as opposed to the option of admitting prosecution history in claim construction, because the intent element of s 53 is inherently uncertain. Moreover, to the extent that there is any justification for excluding prosecution history, it is to simplify the claim construction exercise; but to introduce exactly the same evidence under s 53 means that while claim construction is simpler, the litigation as a whole is at least as complex. Indeed, it will be more complex, because the stakes have been raised from scope to validity, ensuring that all the more money will be put into this uncertain issue.

It is not unlikely that in this case the s 53 issue will ultimately become moot, even if it does go to trial. The claims themselves refer to “the valve member being transversely movable,” and the court may well construe the claims to exclude tools without a transverse valve even without the aid of the prosecution history. That will be all the more unfortunate, as parties in future litigation will have to engage the s 53 issue, instead of what could have been a much simpler matter of claim construction. The SCC in Free World feared opening the “Pandora’s box” [66] of file wrapper estoppel. By refusing to do so, it opened the far more dangerous box of s 53.

Use of Prosecution History in Claim Construction: The First Crack in the Free World Wall?

Distrimedic Inc v Dispill Inc 2013 FC 1043 de Montigny J
            2,207,045

I had somehow missed this decision last fall and was only alerted to it by the case note in the most recent IPIC bulletin. I am very glad it did not slip by me entirely, because it the case that we needed to generate a rational approach to the use of prosecution history in claim construction.

Residents of nursing homes often need a variety of different medicines to be dispensed on a weekly schedule at different times of the day. The ‘045 patent concerns a system for preparing a pill dispenser which facilitates keeping track of which pills are to be dispensed to which patient at what time of day. It consists of a plastic tray (“container-defining sheet”) with depressions to make a series of containers for holding pills to be taken four times per day (breakfast, lunch, dinner, and bedtime) over seven days [22]. After the pills are placed in the container, it is then covered by a sealing sheet on which is printed information about the prescription such as the names of the patient and the pharmacist, the date, and the medications in each container. All this was known in the prior art. It is important that the sealing sheet be properly aligned with the container, and because nursing home staff prepare many of these dispensers on a weekly basis, it is desirable to have a mechanism for aligning the container and the sealing sheet quickly and reliably. This was the problem facing the inventor [24]. The preferred solution, as described in the specification (p 3 line 13-15) was a positioning means comprising “one and preferably two upwardly projecting protuberances on the top surface of the recessed support,” and a corresponding number of “holes” in the container-sealing sheet (and see similarly p 8-9, describing the preferred embodiments).

Of course, an inventor is not confined to the most advantageous embodiment set out in the specification, and all the independent claims originally claimed a broader positioning means [206]:

Positioning means provided on at least the top surface of the container-defining sheet and on the container-sealing sheet to ensure that, in use, after the container-defining sheet is fitted onto the recessed support, the paper covering is peeled off from the bands of the container-sealing sheet and said container-sealing sheet is positioned on top of the top surface of the container-defining sheet, the bands covered with a self-adhesive material and their tearing lines be in exact superposition on top of the flanges and the dotted lines of the container-defining sheet.

These claims were originally allowed by the Patent Office, but the Notice of Allowance was withdrawn, and the claims were rejected when prior art, the Braverman Patent, was brought to the attention of the Patent Office [207].

In correspondence with the Patent Office, counsel for the applicant acknowledged that the Braverman Patent anticipated the invention as claimed, but pointed out that [208]:

BRAVERMAN does not disclose or suggest the following structural feature, which is the key feature of the present invention, namely:

d) positioning means provided on at least the top surface of the container defining sheet and on the container sealing sheet.

Such positioning means were defined in former claims 3 and 4 as being preferably protuberances and holes identified by reference numerals 5, 7 and 15 in the drawings of the present application.

Consequently, in order to overcome the objection based on the Braverman Patent, all the independent claims were amended to add a “wherein” clause specifying that the positioning means comprises

at least one upwardly projecting protuberance provided on the top surface of the recessed support, at least one hole provided into the container-defining sheet and at least one other hole provided in the container-sealing sheet, said at least one hole and one other hole being sized and positioned to correspond to and be engaged by said protuberance.

The defendant’s allegedly infringing container device had a raised outer edge of the container, and the sealing sheet was cut to fit, so that the sealing sheet was positioned by slipping it into the container. Prima facie, the defendant’s device did not use “holes” in the sealing sheet, so a key claim construction question was whether the positioning means defined by the wherein clause was an essential element of the claim.

Counsel for the defendants submitted that “it is difficult to imagine a clearer indication of the essentiality of a claim element than its addition to a claim in order to overcome an objection from the Patent Office” [208]. In my view this argument is entirely compelling. How can we allow a patentee to reclaim in litigation ground that was expressly given up in prosecution? This is the fundamental argument for the doctrine of file-wrapper estoppel, and the facts of Distrimedic powerfully illustrate the force of this argument.

Counsel for the patentee responded that prosecution history simply cannot be used in claim construction, relying on this paragraph from Free World 2000 SCC 66:

[66] In my view, those references to the inventor's intention refer to an objective manifestation of that intent in the patent claims, as interpreted by the person skilled in the art, and do not contemplate extrinsic evidence such as statements or admissions made in the course of patent prosecution. To allow such extrinsic evidence for the purpose of defining the monopoly would undermine the public notice function of the claims, and increase uncertainty as well as fuelling the already overheated engines of patent litigation. The current emphasis on 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. If significant representations are made to the Patent Office touching the scope of the claims, the Patent Office should insist where necessary on an amendment to the claims to reflect the representation.

de Montigny J responded by distinguishing Free World:

[210] While statements or admissions made in the course of patent prosecution shall not be used for the purpose of interpreting a claim, this is not what the Court is called upon to do in the case at bar. A change in the wording of a claim as a result of an objection from the Patent Office is an objective fact from which an inference may be drawn, and is not the same as representations made to the Patent Office.

There is a valid distinction between a statement or admission and a change in the wording of the claim, but, in my view, it is not enough to distinguish Free World, as statements and admissions were given only as examples of extrinsic evidence, and not an exhaustive definition. The general thrust of Free World is that extrinsic evidence and prosecution history generally are to be excluded.

However, the SCC’s holding in Free World is unpersuasive and unprincipled. The specific arguments made in [66] are unpersuasive:

[66] To allow such extrinsic evidence for the purpose of defining the monopoly would undermine the public notice function of the claims,

It would not undermine the notice function, because it operates purely as an estoppel. The worry seems to be that the public might be read the specification and claims, and believe they are safe, only to discover, after the prosecution history is consulted, that they are actually infringing. That would indeed be undesirable, because the public could not tread confidently based on the claims alone, but would have to consult the prosecution history before making any decisions. But this cannot happen. On the usual view, the prosecution history could only be used as an estoppel, preventing the patentee from reclaiming subject matter that it had given up in prosecution. The use of prosecution history can only narrow the claims, not expand them.

and increase uncertainty as well as fuelling the already overheated engines of patent litigation.

It will not increase uncertainty, because the prosecution history estoppel is not a free-standing tool. It will normally operate to clarify the meaning of claims that are uncertain on their face. In principle, the claim might be clear on its face, and then equally clear, but to the opposite effect, when the prosecution history is consulted, but this must be exceedingly rare in practice because it would mean that the examiner accepted a revision to the wording which, on its face, said the opposite of what the examiner had demanded. But in any event, even in that worst case, there would be no increase in uncertainty.

The current emphasis on 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.

It curious that Binnie J considers purposive interpretation to focus on the language of the claims, when Lord Diplock in Catnic [1982] RPC 183, 243 (HL) rejected a “purely literal” approach. The thrust of purposive construction, as compared to what went before, it to place more emphasis on the way a skilled person would read the claims. This necessarily requires going beyond the language of the claims, because a skilled person’s understanding is affected by the context of their experience in the field, their knowledge of the problems faced, and so on. Purposive construction clearly requires more extrinsic evidence, not less, than the lawyerly textual approach which it rejected. I do not see how it is inconsistent with using prosecution history. de Montigny J was quite right to say that “[a] purposive construction should obviously focus on the wording of a claim, obviously, but this is a far cry from saying that nothing else should be considered” [210]

If significant representations are made to the Patent Office touching the scope of the claims, the Patent Office should insist where necessary on an amendment to the claims to reflect the representation.

The Patent Office did insist on an amendment to reflect the representation, and the very reason we want to consult the prosecution history is to clarify the meaning of that amendment. We might always say that the Patent Office should have insisted on a clearer amendment, but the fact that textual expression is never perfect is the reason why claims construction is a crucial exercise in the first place.

The SCC’s position on the use of prosecution history estoppel is also unprincipled. As the SCC noted in Whirlpool 2000 SCC 67 [49e], a patent “is an enactment within the definition of ‘regulation’ in s. 2(1) of the Interpretation Act.” Purposive interpretation is really nothing more than the modern approach to statutory interpretation applied to the specific context of patents: see my article on “The Essential Elements Doctrine” (2011) 22 IPJ 223, 226-40. Prosecution history is the equivalent of legislative history. At one time there was an exclusionary rule against using any extrinsic aids to statutory interpretation, subject to a few narrow exceptions. That rule corresponds almost exactly to the exclusionary rule set out in Free World [66] – but that rule has long been abandoned in respect of legislation generally. (See generally Sullivan on the Construction of Statutes, 5^th ed, Ch 22.) The SCC now routinely consults legislative history in interpreting statutes. The practice is so common that citations are otiose; a quick database search will reveal multiple recent instances from the SCC alone. It is unprincipled to say that legislative history can be used to interpret legislation, and to acknowledge that patents are legislation as a matter of the Interpretation Act, and yet to refuse to use prosecution history, which is the equivalent of legislative history. Indeed, if anything, the argument in favour of considering prosecution history is even stronger than the argument for considering legislative history, as some of the traditional reasons for excluding legislative history, such as the difficulty of deciding who speaks for the legislature (see Sullivan at 595-98), have much less force in the patent context.

We should return briefly to de Montigny J’s distinction between representations and “[a] change in the wording of a claim as a result of an objection from the Patent Office [which] is an objective fact from which an inference may be drawn.” This is a sound distinction. The closest parallel in general statutory interpretation is legislative evolution, which is to say changes made in the succession of enacted texts. The use of legislative history is well established and is relatively uncontroversial, precisely because, as de Montigny J says, it is an objective fact (see Sullivan 577-78). If there is any kind of prosecution history which should be considered, this is it.

Finally, I note that the prosecution history was only one factor considered by de Montigny J in holding that the positioning means specified by the wherein clause was an essential element, and it was almost certainly not a determinative factor (see eg [211-12]). Consequently, de Montigny J’s holding regarding the use of the prosecution history could easily be distinguished by subsequent courts. It will be very interesting to see whether de Montigny J’s holding is indeed ignored, or if it is confined to changes in claim wording, or if it represents the first crack in the Free World wall, which might eventually lead to a more rational and principled approach to the use of prosecution history.