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.
Statutory Interpretation
The main argument in favour of using foreign prosecution history turns on a purposive analysis of the provision. To ignore the reference to the US prosecution history “would emasculate the intent and effect of section 53.1" [71] because limitations added in foreign prosecution and then adopted in the prosecution of the corresponding Canadian claims would be irrelevant, thus allowing applicants to “rely on co-pending foreign applications to effectively avoid any application of section 53.1” [72].
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.” Moreover, this is not a provision where adherence to the text is an apparent drafting error or otherwise results in an absurdity (see eg Egger [1993] 2 SCR 451). As Manson J explained, this textual point is buttressed by sound purposive considerations militating against the use of foreign prosecution history:
[62] To open up foreign prosecution file histories for purposes of Canadian claim
construction is to invite an opening of the proverbial “pandora’s box.” Proof of foreign
law, applicability to Canadian law and distinguishing differences in those laws and
doctrines were never intended in the limited changes introduced under section 53.1. This
new provision is specific to using Canadian prosecution file histories to rebut any
position taken on claim construction.
As a matter of statutory interpretation, “[w]hen the words of a provision are precise and unequivocal,” as in s 53.1, “the ordinary meaning of the words play a dominant role in the interpretive process” (Canada Trustco 2005 SCC 54 [10]), and “the clearer the ‘ordinary meaning’ of the text, the more compelling the contextual considerations must be in order to warrant a different reading of it” (Biolyse Pharma 2003 FCA 180 [13]). Given that the plain meaning of the text of s 53.1 is reinforced by significant purposive considerations, any interpretation that allows scope for the use of foreign prosecution history must place minimal stress on the text, notwithstanding the important purposive considerations in favour of considering foreign prosecution history. 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.
Consequently, 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].1 This is an admirable attempt to thread the needle. If it can reasonably be said that the foreign application, or some part of it, has been made part of the Canadian prosecution history, then it seems reasonable that it should be considered. But even this puts significant strain on the text of the provision.
Manson J held that “foreign prosecution history” would be admissible when it is part of the Canadian prosecution history [77]. Manson J’s interpretation would be entirely consonant with a text that provided that the “Canadian prosecution history” may be considered; but that is not what s 53.1 says. It provides that “a written communication, or any part of such a communication” is admissible if it is between the applicant and “the Commissioner, an officer or employee of the Patent Office or a member of a re-examination board,” which means the Canadian Commissioner and Patent Office (ss 3-4). The provision does not address the admissibility of the prosecution history as a whole, but rather the admissibility of specific documents, and on the face of the provision, such documents must be communications between the applicant and the Canadian examiner. This implies that it is not enough for the US prosecution history to have been made part of the Canadian prosecution history, for example by being referred to in Canadian prosecution. On the face of the text, the only documents that are admissible are communications between the applicant and the Canadian examiner, so that US prosecution history is admissible only to the extent it is discussed in such a communication. Even then, the US communication itself would not become admissible; it would have effect only to the extent it is discussed in the Canadian communication.
This is not necessarily to say that I disagree with Manson J’s holding that foreign prosecution history is admissible when it is made part of the Canadian prosecution history. My point is that it puts considerable strain on the clear language of the text. Nonetheless, some strain on the text is permissible in pursuit of a “harmonious” interpretation based on text, context and purpose. Whether Manson J’s interpretation strains the text too much, is a question best left for another day, particularly because, as discussed below, Manson J’s reasons are entirely consistent with the more restrictive view of the admissibility of foreign prosecution history.
Use of US Prosecution History on the Facts
Manson J held that “extraordinary circumstances” sufficient to warrant admissibility of US prosecution history arose on the facts for three reasons (my numbering). The applicant:
(i) specifically referred to the corresponding US application prosecution history in
communication with CIPO [70], [78];
(ii) “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” [70] (and see [74], [78]); and
(iii) acknowledged that the claims were amended to be substantially the same as claims
submitted in the foreign jurisdiction [74].
The applicant’s statements to CIPO that satisfied the conditions set out by Manson J are evidently those found in the applicant’s correspondence of 24 August 2012, responding to the obviousness rejection of 27 Feb 2012, in which the applicant stated at p2 that “[n]ew claims 1-19 correspond substantially to those submitted during prosecution of a related United States application,” and “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.”2 Manson J held that in light of these statements, the foreign prosecution history was “admissible to aid in a purposive construction of the claims of the Canadian patent” [77] (and see similarly [70], [74]).
Remarkably, after his extensive analysis of the issue and his conclusion that foreign prosecution history was admissible, Manson J never actually referred to the US prosecution history itself anywhere in his analysis on the facts. I suggested above that an alternative interpretation of s 53.1 is that foreign prosecution history is not admissible as such, and may only be considered to the extent it is referred to in communications between the applicant and the Canadian examiner. As I read it, Manson J’s analysis is entirely consistent with this more restrictive interpretation of s 53.1.
The only references to prosecution history in Manson J’s claim construction were as follows:
[70] The language of section 53.1 is limited to communications between the patentee
and the Canadian Patent Office, and generally should be applied in that context.
However, in this case, 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.
[85] In my view, section 53.1 is engaged, and the prosecution history of the ‘376 Patent
is admissible. The prosecution history aids in the purposive construction of the disputed
elements of Claim 1. During prosecution, the Plaintiff introduced both the “stream of air”
and “insulated or partially insulated roasting chamber or tower” limitations to Claim 1.
[86] In a letter to the Canadian Patent Office dated August 24, 2012, 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.” Further, the new claims were
submitted “to encompass both novel and non-obvious subject matter.”
[87] This communication to the Patent Office is clear evidence of the inventor’s express
intention that these two elements, introduced to advance novel and non-obvious subject
matter, are essential (Free World Trust at para 31).
[92] This limitation [to a “stream of air”] was introduced during prosecution to specify a
type of heating. This limitation to the scope of Claim 1 excludes heating by infrared
radiation in the absence of a stream of air.
Paragraph [70] is the only explicit reference to the specific US prosecution history at issue. However, this reference does not turn on the US prosecution history directly, but only on the patentee’s acknowledgment that the Canadian claims were amended to overcome objections made in the US prosecution, without specifying the US examiner’s objections. While somewhat ambiguous, I take it that the intent of Manson J’s statement is that the acknowledgement was made in a communication with the Canadian Patent Office, not the US Patent Office. (It was only after making this observation that he concluded that it was permissible for the Court to look at the US prosecution history; this would be circular if the acknowledgment made by the patentee were found in the US prosecution history.) The remainder of the analysis refers only to the Canadian prosecution history. The letter referred to in [86] is expressly a letter to the Canadian Patent Office, and “[t]his communication” in [87] clearly refers to the same letter. The reference to “[d]uring prosecution” in [85] might possibly be understood as a reference to US prosecution, but, read in the context of the following paragraphs, it is most probably a reference to Canadian prosecution. The statement at [92] is evidently a summary of the preceding discussion, rather than a reference to US prosecution. Only the letter to the Canadian Patent Office is quoted by Manson J; nothing from the US prosecution history is quoted anywhere, nor is any communication to the US Patent Office specifically identified, eg by date.
In summary, this was not a case where the judge discussed and applied the US prosecution history in arriving at his decision, while stating that he would have come to the same conclusion even without it; Manson J simply did not discuss the specifics of the US prosecution history at all. If Manson J had come to the opposite conclusion on the admissibility of foreign prosecution history, his subsequent reasoning could have stood unaltered. I’m not entirely sure what to make of this. The US prosecution history was before him. The specifics of the US prosecution history had been entered into evidence and the defendant TA Foods quoted extensively from the relevant US prosecution history in its supplementary factum of 20 August 2019. It is possible that Manson J implicitly relied on the US prosecution history, and simply failed to mention it in his reasons, but this kind of oversight seems unlikely, especially because the US prosecution history has passages that are much more damning than those relied on by Manson J. I am inclined to think that Manson J made a deliberate decision to refer only to the Canadian prosecution history, and the puzzle then is why he emphasized admissibility of the foreign prosecution history. In any event, the fact that his holding on the admissibility of foreign prosecution history was substantively obiter will no doubt reduce the precedential value of his decision.
Factors Relevant to Consideration of Foreign Prosecution History
Putting that aside, consider the specific circumstances identified by Manson J as justifying consideration of the US prosecution history. Manson J evidently did not intend that the conditions he identified should be considered a definitive test; rather, they constituted the specific “extraordinary circumstances” arising on the facts of the case. With that said, the textual and purposive considerations discussed above mean that some kind of stringent conditions must be imposed before foreign prosecution history may be referred to. It is worth considering the factors set out by Manson J to illustrate some difficulties that will arise in cabining the use of foreign prosecution history. (In this discussion, I assume that if the conditions are satisfied, the foreign documents would themselves be admissible.)
Factor (i) is that the applicant specifically referred to the corresponding US application prosecution history in communication with CIPO. In this case, that reference was found only in the sentence “[n]ew claims 1-19 correspond substantially to those submitted during prosecution of a related United States application” in the applicant’s letter of 24 August. It seems very unlikely that omitting that sentence would have made any difference to the Canadian prosecution, especially given that there was no mention of the US prosecution history anywhere in the requisition of 27 Feb 2012, to which the letter of 24 August was a response. (The examiner’s obviousness rejection was based on the International Preliminary Report on Patentability (IPRP), not on anything in the US prosecution history.)
If the reference to the US prosecution history were omitted, the purposive considerations for and against the use of foreign prosecution history would be unaffected. This suggests that a reference to the foreign prosecution history should not be a strict requirement. If a case arises in which there is a compelling purposive rationale on the facts for considering the foreign prosecution history, such that ignoring it really would emasculate s 53.1, it would be problematic if the use of foreign prosecution history were ignored simply because the applicant had the foresight to avoid mentioning it in correspondence with CIPO. On the other hand, if there is no reference by the applicant to the foreign prosecution history, it is difficult to see how it would be made “part of” the Canadian history. The textual considerations against considering communications with a foreign patent office are already substantial; if there is not a strict requirement of at least a reference to the foreign prosecution history, it becomes extremely difficult to reconcile the use of foreign prosecution history with the text of s 53.1. I see no entirely satisfactory way to resolve this difficulty, but if a choice has to be made, “When the words of a provision are precise and unequivocal, the ordinary meaning of the words play a dominant role in the interpretive process.”
A similar point arises in respect of factor (iii), acknowledgment that the claims were amended to be substantially the same as in the foreign jurisdiction, which is satisfied by the same sentence. What if the applicant refers to the foreign prosecution history, so (i) is satisfied, and Canadian claims were in fact amended to be substantially the same as the claims submitted in that jurisdiction, but the applicant did not specifically acknowledge the similarity, perhaps leaving it to the examiner to recognize the obvious? (Note that this factor was only stated once by Manson J, at [74].)
Factor (ii) is that the applicant must have admitted that the amendments to the Canadian claims limited the scope of the claims “to overcome novelty and obviousness concerns as raised in the US Application prosecution history” [70]. (The statement at [74] is ambiguous as to whether “the claims” refers to the US or Canadian claims, but the discussion at [70] — “to the claims in the ‘376 file history” — and [78] — “the amendments to claims in the Canadian patent” — makes it clear that this refers to the Canadian claims.) I must say that I have considerable difficulty seeing an admission in the statements quoted by Manson J at [86], for reasons I will discuss in more detail in my next post. In any event, even if this passage constitutes the requisite admission, it should be relatively easy for future applicants to avoid engaging this factor, perhaps by including a boilerplate statement to the effect that “I do not admit that these new limitations are essential to the novelty and obviousness of my claims, but in order to proceed to issuance, I will nonetheless agree to narrow them, under protest.”
Finally, factor (ii) also suggests that the use of foreign prosecution history should be restricted to issues of novelty and obviousness. I suspect that Manson J deliberately included this restriction to address the concern he identified about proving foreign law. If the US claims were limited in response to a written description objection, for example, it would certainly require evidence of US law to determine what relevance, if any, it might have for the Canadian claims. However, while Canadian law is generally more similar to foreign law on novelty and obviousness than it is in respect of issues such as utility, overbreadth, written description, plausibility, there are differences nonetheless. For example, the novelty grace period operates differently in US law, and European law does not have a grace period at all. In respect of obviousness, the relevant scope of analogous art for purposes of obviousness is, as I understand it, somewhat different in US law; in UK law, all prior art comprises the state of the art for the purposes of obviousness, while it is not clear whether that is true in Canada. And on the other hand, even though foreign law tends to differ more in respect of other doctrines, there may be issues where restrictions on other grounds may be clearly applicable, for example if the applicant narrows the claim to exclude an inoperable embodiment.
In summary, the text of s 53.1, buttressed by purposive considerations, militates against the use of foreign prosecution history, but there are also significant countervailing purposive considerations. To thread this needle, Manson J held that foreign prosecution history would be admissible where it had been “made part of” the Canadian prosecution history. While this seems reasonable, the specific factors relied on by Manson J appear susceptible to being avoided by a careful applicant. To the extent that foreign prosecution history may be considered even under less stringent conditions, there will be a serious tension with the text of the provision. This issue will likely take many years to work out as Canadian agents begin to tailor their current communications with the Canadian Patent Office accordingly, with the effect to be determined in litigation a decade from now.
I see no easy resolution to this problem. I was at one time inclined to think that prosecution history should be more generally admissible in claim construction (see generally here), but I have become much more skeptical after learning more about how prosecution history estoppel works (or doesn’t work) in the US. Binnie J in Free World was right to describe the use of prosecution history as a Pandora’s box. In Canada, I fear that deciding when foreign prosecution history is admissible will be a Pandora’s box all of its own. If foreign prosecution history is admissible, we will have one Pandora’s box inside another; a Russian doll of Pandora’s boxes, so to speak. This will certainly increase uncertainty certainty and cost in patent litigation. Whether those disadvantages will be offset by improved fairness remains to be seen. What we can say with confidence is that the problem will take many years to work out, particularly as patent prosecution practice today adapts to current case law in ways that will be tested in litigation a decade from now.
Endnotes
1 Manson J relied on the US decision in Abbott Labs v Sandoz 566 F3d 1282, 1290 (Fed Cir 2009) as supporting this approach. However, in Abbott it was the foreign specification itself, not the foreign file wrapper, that was “made part of” the US application, because the US patent at issue claimed priority from it. It seems that while reference to foreign prosecution history is not prohibited (see Caterpillar v Berco (1983) 714 F2d 1110, 1116), it has “a narrow application”: Abbott, 1290.
2 The letter of 24 August is the only communication expressly referred to and quoted by Manson J at [86], and I was unable to find any other reference to the US prosecution history in the Canadian prosecution history, so I take it that all three factors were established by this communication. That communication has no reference to the US prosecution history other than what I have quoted.
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