CA-2025-001040 - [2025] EWCA Civ 903

Grounds 4-6: the law concerning plausibility

AstraZeneca accepts that, if it fails on grounds 1-3, then claim 15 is insufficiently disclosed applying the Warner-Lambert standard. On that hypothesis, AstraZeneca nevertheless contends that claim 2 is valid. In outline, AstraZeneca argues that claim 2 satisfies the requirement of inventive step because the skilled team reading the Patent at the priority date would have no legitimate doubt that dapagliflozin would be useful for the treatment of diabetes, and that the invention of claim 2 is sufficiently disclosed because, as is common ground, the Patent discloses how to make dapagliflozin.

Before considering grounds 4-6 in detail, I would point out that claim 2 is significantly broader than claim 15. It covers all uses of dapagliflozin (including for the treatment of the diseases deleted from claim 14, as well as wholly unrelated diseases, and non-pharmaceutical applications), while claim 15 is limited to the use of dapagliflozin for the treatment of diabetes. As a matter of basic principle, a broader claim to monopoly requires more justification than a narrower claim. Yet AstraZeneca contends that the patentability of claim 2 should be subject to less stringent criteria than claim 15. Moreover, this contention is advanced even though precisely the same disclosure in the Patent is relied upon as supporting both claims. Counsel for AstraZeneca was unable to provide any convincing justification for this.

I would also point out that, as the judge recorded, AstraZeneca does not contend that the identification of dapagliflozin was a patentable invention. This is because the mere identification of a new chemical compound requires no invention: see e.g. T 939/92 Agrevo/Triazoles [1996] EPOR 171 at [2.5.3], Pharmacia Corp v Merck & Co Inc [2001] EWCA Civ 1610, [2002] RPC 41 at [20] (Aldous LJ) and Idenix Pharmaceuticals Inc v Gilead Sciences Inc [2016] EWCA Civ 1089 at [116] (Kitchin LJ). AstraZeneca’s argument for patentability rests upon the proposition that dapagliflozin is useful for the treatment of diabetes. Thus AstraZeneca simultaneously argues that (i) what makes the difference between claim 2 and claim 15 is that claim 2 does not include the therapeutic effect of dapagliflozin as a functional feature of the claim whereas claim 15 does, and (ii) the invention of claim 2 is patentable because of the therapeutic effect of dapagliflozin. Again, counsel for AstraZeneca did not provide any convincing justification for this.

Ground 4 is that the Warner-Lambert test sets too high a standard for plausibility, and must be revisited in the light of G 2/21. Ground 5 is that, in the light of G 2/21, the Court should have treated claim 2, as a claim to a product per se, differently to claim 15, as a claim comprising a functional technical feature. The plausibility of the former should be assessed under inventive step, and the plausibility of the latter under sufficiency of disclosure, with different standards for plausibility applying in those cases: ab initio implausibility in the former case and ab initio plausibility in the latter case.

The short answer to ground 4 is that, as I have already noted, it is common ground that Warner-Lambert is binding on this Court with respect to the sufficiency of medical use claims. Counsel for AstraZeneca did not argue that G 2/21 provided any basis for this Court to apply a different test of plausibility in such cases, and he accepted that the Enlarged Board’s (in English terms, obiter) conclusion at [77] was consistent with that of the majority in Warner-Lambert.

Accordingly, counsel for AstraZeneca concentrated his argument on ground 5. As he accepted, Sandoz v BMS is prima facie binding authority to the opposite effect. Furthermore, he did not challenge the reasoning in Sandoz v BMS at [92] quoted in paragraph 19 above. He nevertheless submitted that this Court was free to depart from Sandoz v BMS, and should do so, on the basis of the exception to the rule that a previous decision of this Court is binding on this Court (and on lower courts) recognised in Actavis UK Ltd v Merck & Co Inc [2008] EWCA Civ 444, [2009] 1 WLR 1186 at [95]: “we are free to decide what this court is to do if it finds that its earlier interpretation of the [EPC] is clearly inconsistent with a settled interpretation given by the Boards of Appeal” (Jacob LJ giving the judgment of the Court of Appeal).

As counsel for AstraZeneca emphasised, decisions of the highest authority in this jurisdiction have recognised the desirability, in the absence of any supranational court with jurisdiction to interpret the EPC, of the UK courts following the settled jurisprudence of the Boards of Appeal: see, for example. Human Genome Sciences Inc v Eli Lilly and Co [2011] UKSC 51, [2012] RPC 6 at [87] (Lord Neuberger). It is important that a harmonised approach to the interpretation of the EPC is adopted by the courts of the Contracting States even if that means the UK courts adopting an interpretation that is contrary to the interpretation they would have adopted if left to their own devices: see, for example, John Wyeth & Brother Ltd’s Application [1985] RPC 545 at 565-567.

Counsel for AstraZeneca’s principal submission was that G 2/21 is itself sufficient basis for this Court to depart from Sandoz v BMS. Although G 2/21 was considered in Sandoz v BMS, it had been common ground between the parties in that case that it made no difference whether the issue was viewed as one of inventive step or as one of sufficiency, whereas AstraZeneca contends that it makes a significant difference. As a result, G 2/21 had been misinterpreted in Sandoz v BMS. His secondary submission was that subsequent decisions of the Boards of Appeal and of courts of other EPC Contracting States confirm that G 2/21 was misinterpreted in Sandoz v BMS and supported AstraZeneca’s reading of it.

So far as G 2/21 is concerned, counsel for AstraZeneca emphasised that the Enlarged Board had expressly differentiated between inventive step and sufficiency at [73]-[77] (see paragraph 31 above). He argued that it followed that the Enlarged Board could not have intended to apply the same criteria to inventive step as to sufficiency, and in particular sufficiency of medical use claims. I acknowledge the force of this argument, but the question remains how the criteria articulated by the Board as being applicable to the assessment of inventive step are to be understood and applied.

Counsel for AstraZeneca submitted that the first limb of the test asks whether the relevant technical effect is part of what is taught by the document. If it is not, then it cannot be relied upon as a putative inventive step. The second limb is a question of technical substance in light of the skilled addressee’s technical understanding: in essence, whether the skilled addressee would understand, in light of their common general knowledge, that the subject-matter of the claim has the technical effect relied upon.

I did not understand counsel for the Claimants to dispute counsel for AstraZeneca’s reading of the first limb. As counsel for the Claimants expressed it, it is a disclosure test. Nor did counsel for the Claimants really take issue with counsel for AstraZeneca’s formulation of the second limb as set out in the preceding paragraph (which I have taken verbatim from paragraph 43 of AstraZeneca’s skeleton argument).

Where counsel parted company was with regard to counsel for AstraZeneca’s further submission that the second limb has no requirement for a positive teaching in the specification rendering the effect plausible, and is therefore akin to the ab initio implausibility test. Counsel for the Claimants disputed this.

Apart from the Enlarged Board’s differentiation between inventive step and sufficiency, counsel for AstraZeneca’s principal argument in support of this submission was that the Enlarged Board had treated the ab initio plausibility lines of cases as being reconcilable with the ab initio implausibility line of cases. He submitted that this could only be the case if one “levelled down” to the ab initio implausibility standard. Counsel for the Claimants riposted that that would mean that the ab initio plausibility line of cases were wrongly decided, and yet the Enlarged Board had affirmed them.

The conclusion I draw from these arguments, revisiting G 2/21 after an interval of two years since BMS v Sandoz, is that, while the Enlarged Board clearly intended to get away from the debates over plausibility in the context of inventive step, the truth of the matter is that the distinction between ab initio plausibility and ab initio implausibility is inescapable. The ab initio plausibility standard requires the claimed technical effect to be rendered plausible by the technical content of the application read with the skilled person or team’s common general knowledge. The ab initio implausibility standard permits a technical effect to be claimed that is not implausible in the light of the technical content of the application read with the skilled person or team’s common general knowledge. As is demonstrated by the arguments in Warner-Lambert, Sandoz v BMS and the present case, this difference can be decisive where the application claims a technical effect without providing either experimental data or theoretical reasoning to support that claim.

I would add that, as Lord Sumption pointed out in Warner-Lambert at [40], the difference between the two standards only really matters in cases where it has subsequently been demonstrated that the technical effect is indeed achieved. In cases like Sandoz v BMS and the present one, the technical effect has subsequently been proved not merely by the in vitro data that is missing from the specification, but also by in vivo experiments and then by clinical trials. In those circumstances it is tempting for courts and tribunals to be swayed by that hindsight knowledge. Tempting as it is, this is contrary to principle for the reasons explained in paragraphs 11-13 above.

I am therefore not persuaded that G 2/21 itself justifies this Court departing from Sandoz v BMS. I turn next to consider subsequent decisions of the Boards of Appeal and of the national courts.

So far as decisions of the Boards of Appeal are concerned, AstraZeneca primarily relies upon the decision of the referring Board of Appeal when it came to apply the Enlarged Board’s answers to the questions: T 116/18 Sumitomo/Insecticide compositions, unreported, 28 July 2023. The Board of Appeal began at [11.1] by expressing the view that the Enlarged Board’s focus in [93] on the application as filed and the filing date “is intended to prevent the filing of applications directed purely to speculative (armchair) inventions made only after the filing”. It reiterated this point at [11.8]. I note that this chimes with the reasoning of Lord Sumption in Warner-Lambert at [22] and [37 (third)].

At [11.10] the Board held that, for the first limb of the Enlarged Board’s test to be satisfied, “the purported technical effect together with the claimed subject-matter need only be conceptually comprised by the broadest technical teaching of the application as filed”, which did not mean that “said effect need … be literally disclosed in it by way of a positive verbal statement”.

At [11.11] the Board held that the second limb was satisfied unless the following question was answered in the affirmative: “would the skilled person, having the common general knowledge on the filing date in mind, and based on the application as filed, have legitimate reason to doubt that the purported technical effect can be achieved with the claimed subject-matter?”. The Board went on in [11.12] to reject the appellant’s argument that the second limb was only satisfied if “the application as filed contains experimental proof that the purported proof that purported technical effect is actually achieved with the claimed subject-matter”. I note that Warner-Lambert does not require experimental proof. On the contrary, plausibility may be demonstrated by experimental data falling short of proof or even by a priori reasoning unsupported by data: see Lord Sumption at [37 (fourth) and (sixth)]. The Board also held at [11.13] that it was not necessary for the application as filed to contain “a positive verbal statement about the purported technical effect”.

At [12] the Board expressly disagreed with this Court’s decision in Sandoz v BMS. It also partially disagreed with the Court of Appeal of the Hague in the case discussed below.

In AstraZeneca’s skeleton argument no reliance was placed upon any Board of Appeal decisions other than T 116/18. It was acknowledged in paragraph 88 that there were other Board of Appeal decisions that had sought to apply G 2/21 and that “they do not all take an identical approach to what G 2/21 means”. In oral argument counsel for AstraZeneca asserted that T 116/18 had been followed in “60-70” decisions, but he did not take the Court to any of these, and only made passing reference to two or three of them.

The Claimants relied upon T 314/20 Boehringer Ingelheim/Glucopyranosyl-substituted benzene derivative (unreported, a decision dated 19 November 2023, but the written reasons for which were only handed down on 20 December 2024) as demonstrating that the Boards of Appeal had not yet arrived at a settled interpretation of G 2/21. In this decision the Board agreed at [6.13.4] with T 116/18 that the purpose of the requirements laid down in G 2/21 was to prevent speculative applications for inventions which were only made after the filing date. At [6.13.5]-[6.13.11] the Board identified two issues with the reasoning in T 116/18. The first issue was that there was an inconsistency in the reasoning: the Board had stated that the Enlarged Board had not referred to any of the plausibility standards in its order, but instead adopted new requirements, and yet the Board had interpreted the second limb as imposing the ab initio implausibility standard. The second issue was that some of the Board’s inferences were not supported by the text of G 2/21. As the Board explained in [6.14], however, it did not need to reach a conclusion as to the correct test to be applied for the purpose of the case at hand.

In these circumstances it seems to me that it is not yet possible to say that the Boards of Appeal have adopted a settled view as to how the test in G 2/21 is to be interpreted and applied.

Turning to decisions of courts of other EPC Contracting States, AstraZeneca focussed on (translations of) decisions from the Netherlands, Spain and Switzerland, while the Claimants focussed on a decision from Norway. Before discussion of these decisions, it should be noted that many of the decisions cited in oral argument or referred to in the parties’ skeleton arguments concerned parallel decisions concerning the apixaban patent that was in issue in Sandoz v BMS. It is common ground that many other courts reached different conclusions to those reached by the UK courts. What matters for present purposes is the reasons for those differing conclusions. It is not uncommon for the courts of different EPC Contracting States to reach different conclusions on the same issue because of differences in the evidence and/or arguments. In the UK, an important aspect of the decisions is that Meade J made a finding, based on the expert evidence, that the skilled team would be aware of other potential reasons for apixaban having been prepared in greater quantities compared to other examples than the reason contended for by BMS, namely that apixaban was the most promising candidate of those exemplified in the application. This evidence does not appear to have featured in a number of the other decisions. There were also differences in the arguments. Finally, the reasoning of the courts differed from one another.

Of the Dutch decisions cited, it is sufficient to refer to those in the first case, which concerned an application for a preliminary injunction against a number of generic companies from marketing apixaban. The District Court of The Hague refused the injunction on the ground that the patent was probably invalid. The Court of Appeal disagreed and granted the injunction: [NL:GHDHA:2023:1593]. The Court considered G 2/21 at [6.5]-[6.13]. The generics argued that a stated technical effect may only be invoked if the skilled person “already understands from the patent application that the stated effect is actually achieved with the invention and the problem is actually solved, at least that this is made plausible”. The Court rejected this argument ([6.5]). The Court interpreted “would derive” in paragraph 2 of the Enlarged Board’s order as having the same meaning as the word “derivable” used in [72] ([6.6]-[6.7]). It noted that the Enlarged Board had differentiated between inventive step and sufficiency, and held that it would be incompatible with this to interpret G 2/21 as requiring that the alleged effect had been plausible when assessing inventive step ([6.8]-[6.9]). It agreed with BMS that the technical teaching of a patent “must be understood as ‘what is taught to the [skilled person] about how the technical problem can be solved with technical resources’” [6.10]. As can be seen from what the Court went on to say in [6.18] and [6.21.3] about the fact that the application disclosed a test with which the skilled person could easily determine that apixaban had a favourable Ki value, this amounts to an acceptance of the argument rejected by Lord Sumption in Warner-Lambert at [53] that it is enough for the application to encourage the skilled person to carry out simple tests identified in the application to confirm the efficacy of the claimed product if carrying out such tests would indeed show that the product is likely to be efficacious. That argument was not revived in Sandoz v BMS.

The Court then said at [6.12]:

“Contrary to what [the generics] argue, this interpretation of G 2/21 by the Court of Appeal does not lead to a free pass for speculative patents. After all, the fact that protection is granted based in a purely speculative patent for an invention that is only made afterward is prevented because it is required that the technical effect is already included by the technical teaching of the application and embodies the same invention that is disclosed therein. Moreover, it is established that EP 415 does not concern a speculative patent. BMS undisputedly argued that the inventors had already determined the favourable affinity and selectivity of apixaban experimentally prior to the submission of the application.”

The first two sentences appear to accept that speculative patents are not permitted by G 2/21. Counsel for AstraZeneca did not defend the reasoning in the second two sentences, which acquit BMS of speculative patenting on the basis that it had positive experimental data in respect of apixaban which it did not include in the patent application. This was not something relied upon by BMS in the English litigation, but it is also a point mentioned in a number of the other decisions. I cannot agree with this for the reasons given in paragraph 13 above. If reliance by the applicant upon secret data is ruled out, as it should be, then I remain of the view that I expressed in Sandoz v BMS at [93] that it is not possible to determine whether a claimed invention is speculative other than by assessing whether the application read in the light of the common general knowledge makes it plausible. As Lord Sumption said in Warner-Lambert at [37(third)], “[t]he disclosure of those grounds [sc. reasonable scientific grounds for expecting that it might well work] marks the difference between a speculation and a contribution to art”.

An appeal by the generic companies to the Dutch Supreme Court was rejected without reasons, from which it may be inferred that the Supreme Court agreed with the reasoning of the Advocate General in his opinion dated 20 December 2024 that the Court of Appeal had made no error justifying cassation. It is sufficient to note that the Advocate General expressed the view that G 2/21 “did not give an unambiguous answer” to the question of the extent to which the technical effect must have made plausible ([4.7]) and “does not solve all problems with plausibility inventiveness” ([4.11]) and that each case turned on its facts ([4.10] and [5.26]). Again, the Advocate General relied on what BMS had actually done before filing the patent, and not what was included in the patent, as an answer to the charge of speculative patenting ([5.8] and [5.14]).

Turning to Spain, AstraZeneca relied upon a decision of the Supreme Court concerning apixaban: Judgment 635/2015 dated 24 April 2025. It is common ground that that Court followed T 116/18 and applied an ab initio implausibility test. It does not appear that the Court was made aware of T 314/20. Furthermore, in concluding that the ab initio implausibility test was satisfied, the Court considered it significant that the ability of apixaban to inhibit Factor Xa, and its selectivity, “could be verified with tests described in the application”. The Court noted that the Court of Appeal of the Hague had reached the same conclusion concerning the application of the G 2/21 test to the apixaban patent.

As for Switzerland, AstraZeneca relied upon a decision of the Swiss Federal Patent Court concerning apixaban in Mepha Pharma AG v Bristol-Myers Squibb Holdings Ireland Unlimited Co dated 5 March 2024. As the Claimants pointed out, however, the Court held at [39] that:

“If the criterion that the claimed technical effect is considered by the skilled person to be embodied in the invention as originally disclosed is understood as the Boards of Appeal did in decision T 116/18 and T 1989/19 [a decision not cited to this Court that the Swiss Court stated had followed T 116/18], namely that this criterion is fulfilled if the skilled person has no reason to doubt that the invention achieves the technical effect, speculative applications are not prevented. In the case of a technical effect claimed in the original application without any basis, there are no reasons for its occurrence, but often also no reasons against its occurrence – especially since, in practically significant cases, it has subsequently been found that the invention achieves the claimed effect.”

This is a clear, and to my mind convincing, rejection of the ab initio implausibility standard.

The Court went on later in the same paragraph to interpret the second limb of the test in G 2/21 as follows (footnotes omitted):

“The second criterion is fulfilled if the technical effect is obvious to a person skilled in the art, taking into account the general knowledge at the time of filing, based on the application as filed. Experimental data or an express statement on the technical effect are not necessary for this purpose. However, since the purpose of derivability is to prevent abusive speculative applications, the hurdle must not be set too high, otherwise inventions that are worthy of protection will not be protected.”

I presume that by “obvious”, the Court meant “apparent”. In determining that this test was satisfied in the instant case, the Court held that it would not be unreasonable to expect the skilled person to determine the inhibition constants of all 110 examples disclosed in the application, and that when they did so they would find that apixaban had a Ki value of 0.08 nm and therefore conclude that apixaban was a potent and effective Factor Xa inhibitor ([42]). This reasoning is similar to that of the Dutch and Spanish courts, but it makes explicit the extent of the burden that this approach places on the public to carry out experiments that the patentee has not done (or if it has done them, not disclosed the results of) if the test is applied, as it should be, to the application. (If the invention is only plausible because of information in the granted patent which is not present in the application, then the patent is invalid for added matter: see Sandoz v BMS at [3] and [53].)

Inspired by the passage from the Swiss Court’s decision that I have quoted in paragraph 123 above, counsel for AstraZeneca argued that speculative patent applications were unobjectionable, and that it was only abusive speculative patents that were objectionable. I am unable to accept this submission for two reasons. First, it does not seem to me to supported by the decision. The Swiss Court accepted that “so-called ‘armchair’ inventions should not be rewarded with exclusive rights” ([39]). Its point was that it was important not to set the hurdle against speculative applications too high (a point which Lord Sumption recognised in Warner-Lambert at [36] and [37(third)]). As we have seen, the Board of Appeal in T 116/18 and the Court of Appeal of The Hague agreed that speculative applications should not be permitted. Secondly, I am unable to see what distinguishes an abusive speculative application from a non-abusive speculative application. Certainly, counsel for AstraZeneca was unable to articulate any workable criterion for distinguishing the two.

The Norwegian Court of Appeal in a decision concerning apixaban dated 3 March 2024 expressly rejected BMS’s argument that G 2/21 had “lowered the requirement for plausibility”. On the contrary, it held that:

“The decisive factor for whether a technical effect can be built upon in the assessment of inventive is whether at the time of application, based on the BMS application in combination with the general subject knowledge, it appeared credible – i.e. plausible – to the expert team that this effect would be achieved.”

On the facts, the Court considered that this test was satisfied. The reasoning was largely based on structural considerations rejected by Meade J on the evidence before him.

The conclusion I draw from this brief review of the case law of courts in other EPC Contracting States is that we are some way from unanimity as to what test G 2/21 lays down and how to apply it.There appears to be an emerging consensus that speculative patents are not permitted, but little agreement as to what constitutes a speculative patent. 

Accordingly, neither the jurisprudence of the Boards of Appeal nor the case law of courts of other Contracting States justifies a departure from Sandoz v BMS any more than G 2/21 itself does.

Even if AstraZeneca were to prevail on the law, and to establish that the correct standard to be applied to the assessment of inventive step was the ab initio implausibility, or no legitimate reason to doubt, standard, the Claimants contend that the Patent fails to satisfy even that standard. In support of this contention the Claimants rely, first, on the judge’s finding at [251] that the four Tanabe Seiyaku papers cited in WO 128 “would give the skilled team reason to doubt whether dapagliflozin would be an SGLT2 inhibitor”, and secondly, the judge’s finding in [259] that the absence of information about the EC₅₀ of dapagliflozin means that the skilled team cannot reasonably predict any useful effect on diabetes.

In my judgment the answer to the second contention is straightforward: there is nothing in the judge’s findings to suggest that the absence of information about the EC₅₀ of dapagliflozin would in itself give the skilled team a reason to doubt the efficacy of dapagliflozin to treat diabetes if they would not otherwise doubt the efficacy of dapagliflozin.

AstraZeneca advances two answers to the first contention in the alternative. The first answer is that there is an apparent inconsistency between the judge’s reasoning at [247]-[251] and what he said in [252] and [262]. At [248] the judge found that the skilled team reading the Patent would also read WO 128, and at [249] he found that they would also read the Tanabe Seiyaku papers. It is on this basis that he made his finding in [251]. Despite this, the judge went on to say in [252] that “it is not necessary to consider whether it would be permissible to rely on information in these cross-referenced documents to establish or support a case of plausibility applying … Warner-Lambert”. Moreover, in [262] he declined to decide whether the Patent satisfies a “legitimate reason to doubt” test on the ground that his findings of fact should be sufficient for a higher court to apply whatever test is appropriate. AstraZeneca contends that the better reading of the judgment is that the judge did not in fact make a finding about the effect of the Tanabe Seiyaku papers, since he did not decide whether they could be relied on. The Claimants dispute this.

In my view the better reading of the judgment is that the judge made findings at [248]-[251] that the skilled team would follow the cross-references and as to the conclusion they would draw from the Tanabe Seiyaku papers. In [252] he pointed out that this did not assist AstraZeneca. He left open the question of whether it was legally permissible for AstraZeneca to rely upon such information to establish or support plausibility. Although he did not spell out his reasons for leaving that open, it seems to me that it is probable that he considered that it was debatable applying Warner-Lambert whether it was permissible to go outside the four corners of the patent read together with the common general knowledge. By parity of reasoning, and having regard to [262], it seems to me that he also left open the question whether it was legally permissible for the Claimants to rely upon such information to establish or support ab initio implausibility.

Although the judge left those questions open, I consider that the logic of the judge’s reasoning applies whatever the test is. I see no reason why the skilled person or team should be confined to the four corners of the patent if it contains cross-references to other documents which they would follow up for the purposes of deciding whether the claims made were plausible or implausible. For the reasons the judge gave at [248] the skilled team reading the Patent would read WO 128 for that purpose, and for the reasons he gave in [249] they would also read the Tanabe Seiyaku papers. Having done so, they would reach the conclusion he set out in [251]. It follows that the skilled team would have legitimate reason to doubt that dapagliflozin is an SGLT2 inhibitor. That in turn means that they would have legitimate reason to doubt that it would be useful for the treatment of diabetes.

That takes me to AstraZeneca’s second answer to this point. If necessary, AstraZeneca contends by ground 6 that the judge erred (i) in taking the Tanabe Seiyaku papers into account and (ii) in finding that they would give the skilled team reason to doubt whether dapagliflozin would be an SGLT2 inhibitor. The difficulty that AstraZeneca faces with this ground of appeal is that it is a challenge to findings of fact made by the judge after hearing expert evidence.

AstraZeneca nevertheless submits that these findings were not open to the judge on the evidence. AstraZeneca argues that finding (i) was not open to the judge because none of the experts gave evidence that the skilled team reading the Patent would cross-refer first to WO 128 and then to the Tanabe Seiyaku papers. AstraZeneca argues that finding (ii) was not open to the judge because the upshot of Prof Potter’s evidence was that what was said about the compound called T-1095a “cannot inform you positively or negatively” about dapagliflozin.

I do not accept these arguments. In the case of finding (i), this was open to the judge on the evidence he referred to in [248] and [249]. In the case of finding (ii), it is fair to note that the judge did not expressly refer to the evidence of any of the experts in [251]. As counsel for the Claimants pointed out, however, Prof Potter was a cross-examined on this topic over 42 pages of transcript, and his evidence cannot be reduced to the soundbite relied upon by AstraZeneca. Furthermore, the judge had the advantage of being able to read the papers and see the experts cross-examined on them. This Court was not even provided with copies of the papers. This is island-hopping with a vengeance. Thus AstraZeneca has not demonstrated that the finding was not open to the judge. On the contrary, it appears to be supported by the abstract from the Hongu et al paper which the judge quoted at [250].