Common General Knowledge and a Reasonably Diligent Search

Gemak Trust v Jempak Corporation 2022 FCA 141 Mactavish JA: Gleason, Roussel JJA revg Gemak v Jempak 2020 FC 644 Lafrenière J

            2,276,428 / 2,337,069

In the decision under appeal Lafrenière J granted summary judgment dismissing Gemak’s action for patent infringement against Jempak. My last post dealt with the FCA’s holding that Lafrenière J erred in deciding the matter on a motion for summary judgment. While that was sufficient to dispose of the appeal, the FCA went on to hold that Lafrenière J also made two further errors, namely an error of law in assessing the common general knowledge, which Mactavish JA chose to address in order to provide guidance in future cases [92], as well as error in assessing testing evidence.

Common General Knowledge

On the first point, in a passage quoted by Mactavish JA [94], with emphasis added, Lafrenière J stated that in assessing the common general knowledge:

[FC 97] The Court must assess what knowledge the skilled person would have obtained through a diligent search conducted using the means available at the relevant time.”

Focusing on the emphasized phrase, Mactavish JA pointed out that there is a well-established distinction between the prior art—any matter available to the public, no matter how obscure [97]—and the common general knowledge, which is more limited than the entire prior art, and indeed does not even encompass all information available to the skilled person.*

Mactavish JA then held that it was an error to apply the concept of a reasonably diligent search to the common general knowledge:

[99] The requirement of the reasonably diligent search has been applied - not with respect to the identification of the common general knowledge of the POSITA - but rather with respect to the discoverability of prior art relevant for the purpose of the obviousness or anticipation analyses: see, for example, E. Mishan & Sons, Inc. v. Supertek Canada Inc., 2015 FCA 163 at para. 22.

As a preliminary point, Mishan v Supertek was an obviousness case, and, so far as I know, the the requirement of the reasonably diligent search has never been applied in the context of anticipation; it has long been accepted that all prior art is relevant to novelty (subject to historical restrictions restricting foreign prior art to printed matter, presumably for evidentiary reasons, which were removed by the new Act in 1993). The concept of a reasonably diligent search had been applied in the context of obviousness, though, as Mactavish JA went on to note, that was changed by Hospira 2020 FCA 30, so that all prior art is now potentially potentially relevant for the purpose of the obviousness analysis [99]–[100]. (To be clear, that is not to say that all prior art is part of the CGK even in the obviousness context.)

Mactavish JA continued:

[100] That said, knowledge that is only discoverable through a reasonably diligent search is not, and has never been, considered to be part of the common general knowledge. The Federal Court thus erred in finding otherwise.

This is a negative definition—it says that information that is only discoverable through a reasonably diligent search is not considered to be “generally known” and so cannot form part of the CGK. This raises the question of whether the CGK excludes information requiring any kind of search. Lafrenière J [FC 97] had begun that paragraph by defining the common general knowledge as being “the knowledge generally known by the skilled person at the relevant time, and includes what the skilled person may reasonably be expected to know and be able to find out.” Mactavish JA [93] quoted this passage as being a correct statement of the law, “at least to the extent that the common general knowledge includes what the skilled person may reasonably be expected to know,” thus casting doubt on the phrase “and be able to find out.” However, in Novopharm v Janssen-Ortho / levofloxacin 2007 FCA 217 [25.3] the FCA defined the CGK as including “what the person may reasonably be expected to know and to be able to find out” (my emphasis). That was recently endorsed by the FCA in Tetra Tech v Georgetown Rail Eqpt 2019 FCA 203 [28]. Mactavish JA cannot have intended to cast doubt on these cases, which were not mentioned.

Further, allowance for at least some degree of search seems necessary. As Laddie J noted in Raychem Corp’s Patents [1998] RPC 31 (Pat) 40:

for something to qualify as common general knowledge it is not necessary to show that all or a majority of the workers in the field knew it, in the sense of having memorised it. For example in the days before the ready availability of pocket calculators, most technicians needed to use log tables for mathematical calculations. Few if any of them could memorise any of the log conversions in such a table yet those conversions would be common general knowledge in the patent sense.

Thus the view that information that can only be found through some sort of search, albeit perhaps very limited, is thus well supported by authority and logic.

This does not imply that the CGK extends to knowledge discoverable only through a reasonably diligent search. Looking up logarithms is routine. Perhaps the CGK includes information that the skilled person would reasonably “be able to find out,” but does not include information that is only discoverable through “a reasonably diligent search.” This distinction would reconcile Mactavish JA’s holding that knowledge that is only discoverable through a reasonably diligent search is not part of the CGK with the FCA decisions in Levofloxacin and Tetra Tech. I have not seen this distinction explicitly made before in Canadian law, but it does have antecedents in UK law.

In Raychem, Laddie J noted that in General Tire [1972] RPC 457 (CA), which remains the leading case on CGK, in Canada as much as in the UK, the Court at 482 described the CGK as being derived from “a common-sense approach to the practical question of what would in fact be known to an appropriately skilled addressee.” Laddie J continued (my emphasis):

The court is trying to determine in a common sense way how the average skilled but non-inventive technician would have reacted to the pleaded prior art if it had been put before him in his work place or laboratory. The common general knowledge is the technical background of the notional man in the art against which the prior art must be considered. This is not limited to material he has memorised and has at the front of his mind. In includes all that material in the field he is working in which he knows exists, which he would refer to as a matter of course if he cannot remember it and which he understands is generally regarded as sufficiently reliable to use as a foundation for further work or to help understand the pleaded prior art.

The notion that the technical background of the skilled person is not restricted to what they would have memorized has been extended to what is sometimes called the secondary common general knowledge. (That phrase seems to have been coined by Arnold J, as counsel in Actavis v Novartis [2009] EWHC 41 (Ch) [128]; while it does not seem to have caught on, even in the UK, it is a convenient term.) As Pumfrey J explained in Novartis v Ivax [2006] EWHC 2506 (Pat) [25]:

It is well settled that the common general knowledge is knowledge that must be attributed to the skilled person, without which the latter may be taken not to be skilled. To it must be added any knowledge that every skilled person should be taken to acquire before he embarks on the problem to which the patent provides the solution, as, for example, the relevant properties of cyclosporin if the problem is to formulate cyclosporin.

As this passage indicates, knowledge that a skilled person would acquire only when faced with a particular problem is not strictly part of the CGK. In KCI Licensing [2010] EWHC 1487 (Pat) [108], Arnold J has described it as “information that, while it was not part of the skilled addressee's common general knowledge, would have been acquired by him as a matter of routine before embarking on the problem to which the patented invention provides the solution.”

So, some information which the skilled person would not have memorized, but would always have readily to hand, is part of the CGK (logarithms), while other such information which the skilled person would acquire as a matter of routine, but only when faced with a specific problem (the properties of cyclosporin), is not part of the CGK. (Always with the proviso that the information must be regarded as a good basis for further action.) Jacob LJ made this distinction in Generics v Daiichi [2009] EWCA Civ 646 [25]:

Of course material readily and widely to hand can be and may be part of the common general knowledge of the skilled person – stuff he is taken to know in his head and which he will bring to bear on reading or learning of a particular piece of prior art. But there will be other material readily to hand which he will not carry in his head but which he will know he can find if he needs to do so (my emphasis).

This distinction may be important in some cases, as Jacob LJ went on to explain at [25]–[28]: in addressing the problem solved by the invention, the skilled person may acquire certain information through routine inquiry, and that information can then be brought to bear on that particular problem. But, unlike the common general knowledge, the skilled person would not have that information at hand in addressing an entirely different problem. If A would be discovered by routine inquiry in addressing problem X, and B would be discovered by routine inquiry in addressing problem Y, this does not mean that it would be obvious to combine A and B to solve problem Z, even though it might be obvious to combine A and B to solve problem Z if both A and B were part of the CGK, strictly defined.

In effect, UK law draws a distinction between two types of information that the skilled person would not have memorized, but which they would find as a matter of routine: there is information which they know is of general usefulness, and which they would apply to any problem, and information which they would only seek out in when faced with a specific problem. The former is part of the CGK, and the latter is not. To draw an analogy, a mechanic might have a toolbox he carries with him to work sites, corresponding to information the skilled person has memorized; then there are tools, such as a hex wrench in a non-standard size, that he does not have in his toolbox, but that he keeps back at the shop, and he knows it is available if necessary, corresponding to logarithm tables. These are both part of the CGK. Then there are special tools to remove a custom fastener on a particular brand of machine. When the mechanic comes across such a fastener, he will know he can readily get it from the manufacturer, and he will know how to use it to fix the machine, without the exercise of any ingenuity on either front; this corresponds to the secondary CGK. But he will not think to combine the special tool for one machine with the special fastener from another machine, to solve a problem he faces on a third kind of machine.

So, at least in English law, there is a distinction between information which the skilled person knows is available as a matter of routine, and information which the skilled person can find without undue burden when faced with a specific problem. The former is part of the CGK and the latter is not.

This may be the kind of distinction Mactavish JA had in mind, though I’m not entirely sure. After all, she seemed to cast doubt on the idea that the CGK includes information that the skilled person would be able to find out, but it is clear that information may be part of the CGK even if the skilled person would not have it memorized. And it is by no means clear that the distinction necessary to reconcile Mactavish JA’s decision in this case with Levofloxacin and Tetra Tech—which is to say the distinction between information the skilled person would be able to find out and the information discoverable in a reasonably diligent search—corresponds to the distinction drawn in UK law. On the other hand, if we consider that the information discoverable in a reasonably diligent search corresponds to the secondary common general knowledge, as that term is used in English law, then it is indeed true that such information is not and never has been part of the CGK.

I must say that it strikes me as somewhat harsh for Mactavish JA to have criticized Lafrenière J on this point. The distinction is “subtle,” at least in the opinion of Kitchin J (now of the UKSC), at first instance in Generics v Daiichi [2008] EWHC 2413 (Pat) [40]. Moreover, the error, such as it was, made no difference in this case. There was no dispute as to the common general knowledge [FC 4], [FC 101], so there is no particular piece of information that was include by Lafrenière J that would be excluded by Mactavish JA’s approach.

Further, it is worth pointing out even if information that is only discoverable in reasonably diligent search is not part of the CGK, that does not imply that it cannot be applied outside the context of obviousness. For example, it is very well established that patent is enabling even if the skilled person cannot practice the invention without carrying out some experiments, so long as those do not require undue effort: see BRP v Arctic Cat 2018 FCA 172 [78]. Presumably the skilled person can also be expected to carry out a routine literature search. When the patent claims a compound that can be made using conventional methods, it is common for the specification to say as much, typically referring to a leading handbook or a journal article for the details of the method. Such a specification is undoubtedly sufficient, even if the ordinary skilled person might have to actually consult the work referred to in order to carry out the synthesis. Suppose the specification stated that the compound could be prepared by conventional methods, but failed to actually cite the leading textbook. The specification would no doubt still be sufficient if the details of the method could be found in the standard textbook that the skilled person would consult as a matter of routine. The parallel with secondary CGK in the obviousness context is exact, as the skilled person attempting to practice the invention in light of the specification is faced with a specific problem, and so can be expected to carry out routine research to address that problem.

So far as I can tell, the distinction between information that a skilled person knows of and would be able to find out as a matter of routine, and information that the skilled person would find out after a search in light of a particular problem, only matters in the context of obviousness, and the problem of combining obscure prior art. The point made by Jacob LJ, that secondary CGK is not CGK strictly speaking, means that two pieces of prior art that are both only secondary CGK cannot be combined to make the invention obvious. This point would be better addressed explicitly, as part of that ongoing discussion, rather than with an abstract definition of the CGK.

*As an aside, Mactavish JA stated that a piece of knowledge only becomes general knowledge “when it is generally known” and “accepted without question” by those skilled in the art [96], quoting from Cefaclor liability 2009 FC 991 [97], which quoted from General Tire [1972] RPC 457 (CA) 482–83, which in turn quoted from British Acoustic Films Ltd v Nettlefold Productions (1936) 53 RPC 221 (Ch) 250. However, as the English Court of Appeal noted in General Tire, 483, in a passage also quoted in Cefaclor liability 2009 FC 991 [97], “accepted without question” may be “putting the position rather high”; the Court of Appeal indicated that “generally regarded as a good basis for further action” is preferable. The “good basis for further action” formulation is now generally accepted: see also Mylan v Eli Lilly / tadalafil 2016 FCA 119 [24]. Nothing turned on the point and I am sure that Mactavish JA did not intend to hold that “accepted without question” is the correct standard, as her focus was on the distinction between the prior art and the common general knowledge; that is, the decision focuses on what it means for information to be eligible to be part of the CGK because it is “generally known”, while recognizing that not all information that is generally known is part of the CGK.

Testing Evidence

Turning to the testing evidence, a key issue was whether Jempak’s detergent pods had detectable levels of carboxymethyl cellulose [CMC] in the coating, which was an essential element of the claims. Jempak’s expert gave evidence that there was no detectable CMC, and this evidence was criticized by Gemak’s expert on the basis that the testing method used by Jempak’s expert was not sufficiently sensitive. Lafrenière J rejected this, partly on the basis that Gemak’s expert did not have experience with the kind of detergent formulations at issue, and consequently he “did not provide an opinion from the perspective of the skilled person of the Patents” [FC 129], [107]. But Mactavish JA pointed out that Gemak’s expert was not construing the claims, but rather was providing expert evidence with respect to the question of infringement. Infringement is a question of fact. In this case, the question was whether or not the coating in fact contained CMC, not whether a person skilled in the art would have been able to detect the CMC as of the date of publication. Consequently, there is no requirement that the testing method used by the expert witness is one that would have been used by the skilled person:“Reviewing courts have . . . endorsed the use of analytical chemistry techniques that would not have been available to a POSITA at the relevant time or that would have been beyond the abilities of a POSITA” [108].

Putting the Brakes on Summary Disposition?

Gemak Trust v Jempak Corporation 2022 FCA 141 Mactavish JA: Gleason, Roussel JJA revg Gemak v Jempak 2020 FC 644 Lafrenière J

            2,276,428 / 2,337,069

The past couple of years have seen a significant shift in practice related to summary judgment and summary trial. The old practice, as I understand it, is that summary judgment was almost never granted, on the view that patent trials normally turn on the expert evidence and the credibility of expert witnesses can only properly be assessed in a viva voce trial. As Manson J put it in Canmar v TA Foods 2019 FC 1233 [45]–[46], for a decade after the FCA restricted the availability of summary judgment in MacNeil Estate 2004 FCA 50, “summary judgment as a just, efficient and expeditious means to resolve disputes on a proportionate basis was lost” [45], until Hryniak v Mauldin 2014 SCC 7 resulted in “a culture shift” that “opened the door for a more reasoned approach to the use of summary judgment motions” [46]. I believe Canmar, affd 2021 FCA 7, was the first in the new wave, but since then we have seen an upsurge in decisions granting summary disposition. The FCA decision in Gemak v Jempak suggests that the brakes might need to be applied.

In the decision under appeal Lafrenière J granted summary judgment dismissing Gemak’s action for patent infringement against Jempak. Lafrenière J acknowledged that the court has been reluctant to grant summary judgment in patent cases, because they often turn on the credibility of expert witnesses [77], [FC 4], but he nonetheless held that summary judgment was appropriate in this case because “there is no substantial conflict of opinion evidence. Jempak’s expert is the only witness who provides an informed and purposive claim construction of the terms at issue from the perspective of a skilled person” [FC 4], [78]. Lafrenière J entirely dismissed the evidence of Gemak’s expert, Dr Frankenbach [FC 110], [81]–[82], on the basis that she gave “evasive and defiant responses”, “conducted herself like an advocate instead of a neutral objective expert” and generally “failed to provide fair, objective and non-partisan opinions” [FC 104], [FC 110], [80]–[81]. However, Mactavish JA pointed out that much of the difficulty in Dr Frankenbach’s testimony was due to the combative stance taken by counsel for Gemak, and the conduct of counsel should not reflect negatively on the credibility of the witness [84]–[85].

Further, Lafrenière J remarked on “evasive and defiant responses from Dr. Frankenbach” and found the evidence of Dr. Frankenbach to be “wanting and problematic in many respects.” But Mactavish JA stated that

[86] a review of the transcript of her cross-examination suggests other possible interpretations of her evidence. Rather than being ‘evasive and defiant’, the transcript could be read to suggest that Dr. Frankenbach was a careful witness, one who wanted to be sure that she understood questions before answering them, and one who would not allow herself to be pushed around by counsel.

Importantly, she went on to state that “it is very difficult to infer a hostile attitude on the part of a witness from a bare review of a transcript, in the absence of an ability to evaluate his or her viva voce testimony” [87].

The FCA consequently held that it was “a palpable and overriding error on the part of the Federal Court to make the negative credibility findings that it did with respect to the evidence of Dr. Frankenbach based on a transcript of her testimony, and to decide the case in reliance on those findings” [90]. The FCA directed that the matter proceed to trial [112].

The interesting question arising from this decision is whether it is a signal from the FCA that the recent enthusiasm for summary disposition needs to be tempered, or whether the decision simply turned on the facts of the particular case.

In support of the view that it turned on the facts of the case, the key point in the FCA holding was that Lafrenière J’s decision explicitly turned on a negative credibility findings, and it was an error to make such a finding based on a transcript. On the other hand, the FCA took the opportunity to review the principles governing summary judgment at some length [61]–[74], even though there was no dispute between the parties as to those principles [61]. Many of Mactavish JA’s statements were phrased in general terms, and she emphasized the importance of viva voce evidence: “The jurisprudence is clear that issues of credibility ought not to be decided on motions for summary judgment” [68]; “the difficulty in assessing the credibility of expert witnesses in complex patent cases on the basis of voluminous paper records was long recognized” as a defect in the old PM(NOC) procedure [69]; and “ the lack of viva voce testimony provided for in the NOC Regulations was one of the inadequacies in the old regime” that led to it being modified to provide for a full trial [70]. These are exactly the reasons why summary judgment was traditionally avoided. Further, Mactavish JA summarized by saying that “[c]ases should therefore go to trial where there are serious issues with respect to the credibility of witnesses” [71]. This was phrased as a general propostion. Moreover, in support she cited, inter alia, MacNeil Estate 2004 FCA 50—the decision which, in Manson J’s account, put the brakes on summary trial in the first place. She also relied on Suntec v Trojan Tech 2004 FCA 140, which also predates Hryniak. Mactavish JA made the general observation that “while patent infringement issues are not by definition excluded from the ambit of the summary judgment process, they tend to raise complex issues of fact and law that are usually better left for trial” [91]. While she did go on to say that “this is not a hard and fast rule” and “there will be cases where use of the summary judgment process is appropriate,” this is a clear statement of a general principle, not a point that was confined to the facts of this case.

While the FCA discussion focused entirely on summary judgment, it seems to me that many of the observations, such as those related to the need for viva voce evidence, apply with equal force to summary trial; the FCA’s central holding was that it was “a palpable and overriding error on the part of the Federal Court to make the negative credibility findings that it did with respect to the evidence of Dr. Frankenbach based on a transcript of her testimony, and to decide the case in reliance on those findings” [90].

Time will tell, but for now my sense is that the FCA is sending a message that the Federal Court should be more cautious in granting summary disposition, at least when the credibility of witnesses is involved—but that will often be the case.

The problem is a difficult one. On the one hand, it would be desirable to reduce the cost of patent litigation, particularly in contexts where the expense of patent litigation is exploited to extract unjustifiable settlements. On the other hand, assessing patent validity and infringement on a reduced record may be unfair. Encouraging access to justice is certainly desirable, but the ‘justice’ aspect is as important as the ‘access’ part. Flipping a coin would be much cheaper than trial as a means of settling patent disputes, but no one thinks it is better for that reason. How to strike the balance is a very difficult question, as the cost and complexity of patent litigation cuts both ways.

With all that said, I will end with a very tentative proposal. Before American Cyanamid [1975] UKHL 1, a motion for an interlocutory injunction required a showing of a prima facie case on the merits. My understanding is that parties would use this to get what amounted to a non-binding opinion on the merits, on an abbreviated record, from the judge who would ultimately be hearing the case. The parties would often then settle in light of that opinion, but a party who thought they could do better on a full record was fully entitled to go to trial. (Over time the abbreviated record got longer and longer—the hearing in Cyanamid was three days at first instance and eight days in the Court of Appeal. One solution to that problem is better case management, rather than doing away with consideration of the merits, and it seems that most jurisdictions are now going that way.)

I wonder if it might be possible to adapt the motion for summary disposition to a similar effect. (I expect this would require an amendment to the Federal Courts Rules.) In particular, if the judge hearing the motion for summary disposition is of the view that one side had a prima facie weak case, but the matter was not suitable for summary disposition because, eg it was necessary to assess credibility viva voce, the judge might dismiss the motion, but at the same time issue what would amount to a non-binding direction on costs, to the effect that if the case turned out to be as weak as it appeared to be, costs would be assessed against the party with the weak case at a substantially elevated scale — say 75% rather than 25%. It would be non-binding, in the sense that the elevated costs award would not be automatic if the party against whom it was issued lost at trial. Rather, the trial judge would take it into account and award elevated costs if the party against whom it was issued had not improved their case at trial. If the party lost, but the judge was of the view that the full trial really had improved the court’s ability to assess the evidence, it would be open to the judge to ignore their prior directive and award costs on the normal scale. The party with the weak case would thereby be put on notice that there would be significant costs consequences if it proceeded to trial, unless it was confident that a trial really was necessary to present it’s position fairly. As with the old interlocutory injunction practice, this would provide an incentive to settle, based on a non-binding opinion on the merits from the judge who would ultimately hear the case. The difference is that in the interlocutory injunction case, the question was whether the plaintiff had a strong case, and in this suggestion, the question is whether one of the parties has a weak cases; but the basic concept of a preliminary assessment of the merits on reduced record is the same. Of course, a judge hearing a summary disposition motion would not be required to issue any such directive in dismissing the motion; it would remain open to the court to simply hold that the matter was not suitable for summary disposition.

I’m not a litigator, so I don’t have a good sense of whether this would work in practice. Indeed, I hesitated to post the suggestion at all. But I decided I might has well make the suggestion for consideration.

Date for Assessing Sufficiency Redux

Pharmascience Inc v Bristol-Myers Squibb Canada Co 2022 FCA 142 Locke JA: de Montigny, Monaghan JJA affg 2021 FC 1 Zinn J FC Selection

2,461,202 / 2,791,171 / apixaban / ELIQUIS

In Teva / sildenafil 2010 FCA 242 [79] and Idenix v Gilead 2017 FCA 161 [46], the FCA held that the correct date for assessing sufficiency is the filing date, not the date of issue. In my post “What Is the Date for Assessing Sufficiency?” I indicated that Locke JA in Pharmascience v Bristol-Myers Squibb 2022 FCA 142 may have reopened the question, with a decision that might be taken to suggest that the date of issue was appropriate. Steve Hundal, has a recent blog post arguing that on the contrary, Locke JA was simply saying that it is the specification as issued that is relevant in assessing sufficiency, without disturbing the prior FCA holding that sufficiency is assessed in light of the common general knowledge as of the filing date. This is in the same way that novelty is assessed as of the claim date, but on the basis of the claims as issued. On reflection, I’m sure that is indeed the best way to read Locke JA’s decision.

In my defence, I will say that Locke JA indicated that the question was “the date for determining sufficiency” [26] “the relevant date for determining patent sufficiency” [28], and he spent several paragraphs discussing Zoledronate 2013 FC 283 [179]–[188] which clearly concerned the date for assessing sufficiency. (He also adverted to Merck v Apotex 59 CPR(3d) 133 (FCTD) [115]–[120], which also, on it’s facce, concerns the date for assessing sufficiency, though both the argument and the analysis in Merck v Apotex were a bit peculiar.)

But Mr Hundal is right to point out that there are other passages that indicate that Locke JA’s was simply saying that sufficiency is assessed in light of the specification as issued, not at some earlier date: see [32], [33]; and [31], which draws the parallel with assessing claims as issued for novelty and obviousness as of the claim date, and for utility as of the filing date. Further, I now see that the distinction between the date for assessing sufficiency, and the document to be assessed—the specification as filed or at some later date—is made very clearly by Zinn J at first instance: see eg [FC 37], [FC 43]. And this way of reading Locke JA’s decision has the great virtue that it is entirely consistent with the holding in Teva / sildenafil or Idenix v Gilead that sufficiency is assessed as of the filing date; it also explains why Locke JA did not mention those cases.

So, I think we can consider it still settled that the filing date is the correct date for assessing sufficiency, though it is the specification as issued that must be sufficient, not the specification as it was at some earlier date.

Now, there is still a problem. Some of Locke JA’s remarks could be taken to suggest that amendments to the specification might make a specification sufficient even thought it was insufficient as filed: eg “subsection 27(6) and section 38.2 of the Patent Act, while limiting the matter that can be added to a patent application by way of amendment, do permit amendments, and without restriction as to whether such amendments might buttress the sufficiency of the specification” [36, my emphasis]; and “it would effectively read out subsection 27(6), which contemplates amendments to bring the application into compliance with the sufficiency requirements” [33]. This raises some difficulties. In Idenix, the specification at filing did not enable a skilled person to synthesize the claimed compound, and indeed, the applicant did not know how to do so. The information on how to make the compound was subsequently made public, prior to issuance. It would be problematic if the applicant could have incorporated that into the specification, thereby rendering it sufficient: as Lord Hoffmann noted in Biogen v Medeva [1996] UKHL 18 [81],“[i]t would be illogical if a patent which ought to have been rejected [on examination by the Patent Office] is rendered immune from revocation [by the court] by advances in the art between the date of application and the publication of the specification.”

I think the answer to the problem is that, as Mr Hundal notes, “[t]here is the practical question of whether the specification as issued can differ appreciably from the specification as filed, given that section 38.2 of the Patent Act does not allow amendments that cannot be reasonably inferred from the specification and drawings contained in the application on its filing date.” Locke JA is right to say that s 27(6) and s 38.2 contemplate amendments to the specification, and they do not expressly exclude amendments which buttress sufficiency. But the “reasonably be inferred” standard from the 38.2 is restrictive, and probably does, as a practical matter, exclude amendments that would cure an insufficient specification. And while Locke JA noted that 27(6) “contemplates amendments to bring the application into compliance with the sufficiency requirements” [33], any such amendments are still subject to s 38.2.