UK Supreme Court confirms Warner-Lambert patent claims insufficient…

35 minute read
21 November 2018


…and leaves readers wondering whether the internet is yet available in the Supreme Court's library (!)

The UK Supreme Court has handed down its long-awaited judgment in Warner-Lambert v Generics & Anr [2018] UKSC 56. It took the form of separate judgments from four Law Lords, who agreed that key claims of Warner-Lambert's patent were invalid and could not be amended, but disagreed about almost everything else.

Deciphering what exactly the Supreme Court has ruled is not straightforward. What we can say is that the concept of plausibility is now not a "low, threshold test" (as the Court of Appeal had indicated); but the Law Lords were split on what the test should be. Consequently the law in this area has become unsettled. Further, the interpretation of Swiss form claim language and the operation of the infringement provisions in respect of such claims has been unsettled by the Supreme Court's obiter reasoning on these issues, some of which appears to conflict with previous judgments of the court without express departure.

What is clear is that the Supreme Court's latest patent judgment gives commentators much to discuss, and it is to be expected that the issues of sufficiency and infringement of Swiss form claims will need to be revisited by the court in another case.


Swiss form claims are a construct introduced by the European Patent Office (EPO) as a way of enabling patent protection to be awarded for inventions residing in a new therapeutic use of a known medicine - which can require considerable research investment - while navigating past the legislative provisions preventing both the re-patenting of a substance per se and the patenting of a process of treating a patient. Such a claim takes the general form "use of X in the manufacture of a medicament for the treatment of Y".

The legislation has since been altered to enable second medical use inventions to be claimed in "X for the treatment of Y" (known as 'purpose-limited product' or 'EPC 2000') format. Claims in Swiss form subsequently ceased being granted. However, we can expect the courts to be called upon to resolve disputes concerning existing Swiss form claims until the 2030s. The enforcement of such claims in practice has at times proved to be problematic, as demonstrated by the Warner-Lambert case.

The Warner-Lambert case also raised issues going to the heart of patent law more generally, including the interpretation of claim language and the requirement of sufficiency, and on which the Supreme Court was also called upon to rule. Unusually, the case was heard at a time when the Supreme Court had no intellectual property specialist amongst its members.

Following a four day trial in February 2018, the judgment of the Supreme Court was handed down on 14 November 2018. It took the form of four separate judgments, written by Lords Sumption (with whom Lord Reed agreed), Briggs, Hodge and Mance. The extent of their agreement was limited, and the consequence of the Supreme Court's judgment for the direction of several aspects of patent law is likely to remain unsettled until further, clearer, Supreme Court guidance is handed down.

In this article, we take a look at what this means for you, covering the following:


The question of amendment arose after the first instance judge (Arnold J) had handed down his judgment but for the purposes of this article it is convenient to discuss this first.

Following the judge's finding that key claim 3 was invalid for insufficiency, Warner-Lambert applied for conditional amendment of that claim (in the event its appeals on validity were unsuccessful), to add words to the end of claim 3 with a view to limiting its scope down to the subject matter found by the judge to be plausible.

The Patents Court, Court of Appeal and Supreme Court were unanimous in refusing to allow Warner-Lambert to seek this re-writing amendment. In short, irrespective of Articles 105a-105c of the EPC 2000, which enables the claims of a European Patent to be centrally limited in all the designated Contracting States by a single application to the European Patent Office, Warner-Lambert's application to the English court was governed by national law and procedure. Applying the test articulated by the House of Lords in Johnson v Gore Wood & Co [2000] UKHL 65, the application was an abuse of process because it could and should have been made prior to trial. The judge had not erred in striking it out.


Interpretation of "neuropathic pain" in claim 3

Underpinning the question of whether Warner-Lambert's patent was invalid for insufficiency was a question regarding the interpretation of the language of claim 3. This claim was in Swiss form, to pregabalin for the treatment of "neuropathic pain". Should this be interpreted as covering both the peripheral and central types of neuropathic pain or as limited to "peripheral" neuropathic pain?

The Patents Court and the Court of Appeal agreed with the defendants that the claim covered both types of neuropathic pain, and this was confirmed by the Supreme Court. One of the Law Lords, Lord Mance, said that he would have been tempted by Warner-Lambert's case that in the context of the specification, claim 3 should be limited to peripheral neuropathic pain, but he noted "force" in points made by Lord Briggs (in paragraphs 104(4)&(5)) regarding the skilled person's understanding of the term, and in these circumstances did not press his reservation on construction.

The discussion of the legal principles regarding construction was confined to Lord Briggs' judgment. He referred to the Patents Act (section 14(5)(a)&(b) and section 125(1)&(3)), the Protocol on the interpretation of article 69 of the European Patent Convention (EPC) and article 84 EPC. He then considered jurisprudence regarding whether a claim capable of two constructions should be given the construction which would uphold the validity of the patent. Originating in contract law, the principle was considered in patent contexts in Parkinson v Simon (1895) 12 RPC 403 (House of Lords), Kirin-Amgen Inc v Roche Diagnostics GMBH [2002] RPC 1 (Neuberger J) and Smithkline Beecham plc's Patent [2003] EWCA Civ 872. Lord Briggs also noted dicta from the United States, Canada and Australia.

Lord Briggs concluded that particularly in the case of second medical use patents, there is a need for legal certainty in fixing the dividing line between the original use and the new one. An issue as to the construction of a Swiss form claim should therefore be addressed, as far as possible, by deciding what it really does mean, rather than by too easily accepting that there is ambiguity, and resolving it "by inventing a meaning which saves the claim from invalidity". Further, he did not consider claim 3 to be ambiguous in any case, so the condition to applying an interpretive presumption was not present.

Notable for its absence from the Supreme Court's judgment is any discussion of the modern jurisprudence on the general principles governing the interpretation of patent claims. Catnic v Hill & Smith [1982] RPC 182 (House of Lords) is noted as greatly diminishing the importance of dicta regarding validating construction in modern times. The judgments of the House of Lords in Kirin-Amgen v Hoechst Marion Roussel [2005] RPC 9, the Supreme Court in Actavis v Eli Lilly [2017] UKSC 48 and the Court of Appeal in Virgin v Premium [2009] EWCA Civ 1062, are not referred to or cited.


Having interpreted "neuropathic pain" as covering both the peripheral and central types of neuropathic pain, the Patents Courts and the Court of Appeal agreed that the assertion that pregabalin was effective for the treatment of central neuropathic pain was not, in light of the contents of the specification, "plausible". As a result the claim to "neuropathic pain" (claim 3) more generally was invalid for insufficiency (excessive claim breadth). This was despite there being no dispute that pregabalin is, in fact, effective at treating both the peripheral and central types of neuropathic pain. Similarly, claims 4 and 6, which were or could involve central neuropathic pain, were invalid.

However, the Patents Court and Court of Appeal were agreed that claims 10, 11 and 12 of Warner-Lambert's patent were to types of pain regarded as peripheral types of neuropathic pain. For peripheral types of neuropathic pain the claim to efficacy was plausible, and therefore claims 10, 11 and 12 were sufficient and valid.

The Supreme Court was unanimous in agreeing with the lower courts that claim 3, 4 and 6 did not meet the appropriate test for plausibility and were therefore invalid for insufficiency.

However, that was about the limit of the extent of agreement within the Supreme Court.

The majority (Lords Sumption, Reed and Briggs) disagreed with Floyd LJ's statement that the EPO and domestic cases "indicate that the requirement of plausibility is a low, threshold test" (paragraph 46 of the Court of Appeal's judgment [2016] EWCA Civ 1006).

Lord Sumption considered the EPO's Enlarged Boards of Appeal judgments in MOBILE G2/88 and BAYER G 6/88, the Technical Boards of Appeal judgments in EXXON T 409/91, AGREVO T 939/92, JOHNS HOPKINS T 1329/04, BRISTOL-MYERS SQUIBB T 0488/16, SALK T 609/02, IPSEN T 0578/06, INTERVET T 0716/08, ALLERGAN T 1437/07, BRISTOL MYERS SQUIBB T 950/13 ASTRAZENECA T 1677/11 and MERCK, SHARP & DOHME T 1329/04; the House of Lord's judgments in Biogen v Medeva [1997] RPC 1 and Conor v Angeiotech [2008] RPC 28; and Lord Neuberger's judgment in Prendergast's Applications [2000] RPC 446.

Lord Sumption said that plausibility is not a term of art, and its content is inevitably influenced by the legal context. In the present context ([37]-[39]):

the proposition that a product is efficacious for the treatment of a given condition must be plausible; it is not made plausible by a bare assertion to that effect, and the disclosure of a mere possibility that it will work is no better than a bare assertion;

there must be a reasonable prospect that the assertion would prove to be true based on a direct effect on a metabolic mechanism specifically involved in the disease; it is not enough that the patentee can prove that the product can reasonably be expected to work in the designated use;

where the condition identified embraces a number of different pathologies, and the claim is construed as asserting the efficacy of the product for each of them, the assertion must be plausible in relation to them all;

the effect on the disease process need not necessarily be demonstrated by experimental data; it can be demonstrated by a priori reasoning, for example by pointing to some property of the product which would lead the skilled person to expect that it might well produce the claimed therapeutic effect; or to some unifying principle that relates the product or the proposed use to something else which would suggest as much to the skilled person; and

later data cannot be relied upon to support efficacy; sufficiency is a characteristic of the disclosure.

Lord Sumption said that as Kitchin LJ put it in Regeneron v Genentech [2013] EWCA Civ 93 at [100], "it must be possible to make a reasonable prediction that the invention will work with substantially everything falling within the scope of the claim or, put another way, the assertion that the invention will work across the scope of the claim must be plausible or credible".

Applying this test, the same majority concluded that Warner-Lambert's claim to efficacy was not plausible in respect of both the central and peripheral types of neuropathic pain. Not only was claim 3 (and 4 & 6) invalid, but claims 10, 11 and 12 of Warner-Lambert's patent were invalid too. Let us explain briefly why:

The experimental data in the specification was predictive of efficacy in inflammatory pain rather than neuropathic pain. Warner-Lambert contended that the specification nevertheless rendered efficacy in neuropathic pain plausible because of a unifying principle known as 'central sensitisation', which the judge found was well-known at the priority date. Central sensitisation referred to sensitisation of neurons in the dorsal horn to peripheral painful stimuli. However while this was understood to contribute to inflammatory pain and peripheral neuropathic pain, both of which originate in the peripheral nervous system, the judge said that it could not contribute to central neuropathic pain, which has nothing to do with damage to the peripheral nerves. This meant that the claim to central neuropathic pain was not plausible. However, applying "a relatively low threshold" or "a low, threshold" test to plausibility, the judge and the Court of Appeal respectively were satisfied that efficacy in peripheral neuropathic pain was plausible. Arnold J said that the test was "just" met. However, Lord Sumption said that applying the test for plausibility as he had described it, the judge's findings did not support a conclusion that peripheral neuropathic pain was plausible. Lord Sumption said:

"The question, it must be remembered, is not whether it is plausible but whether the specification discloses something that would make it so in the eyes of the skilled person".

Lords Hodge and Mance thought Lord Sumption put the test too high. They agreed that ([181]):

"…the recent decisions of the Board (a) require that the therapeutic effect of the medication appears plausible from the data in the patent interpreted in the light of the common general knowledge, (b) do not require that the patent discloses experimental evidence to demonstrate that plausibility unless there is an allegation, supported by sufficient evidence, that the invention does not work, but (c) allow the plausibility to be reinforced by considering evidence which post-dates the patent (although later-published data are not admissible if they alone render the therapeutic effect plausible), (d) take account of the ease with which the therapeutic effect can be ascertained using straightforward tests which are known in the prior art, and (e) where the data in the specification have made the claimed therapeutic effect plausible, place a burden on an objector to substantiate doubt that the desired effect can be achieved."

Adopting this standard, the same minority concluded that the judge had not erred in finding that there was enough material to make it plausible that pregabalin would be efficacious for the treatment of peripheral neuropathic pain. Accordingly, both would have dismissed the defendants' cross appeal in respect of claims 10, 11 and 12 and confirmed them as valid. However, Lords Hodge and Mance also agreed that claim 3 (and 4 & 6) did not satisfy this test in respect of the central type of neuropathic pain, and so was invalid.

Notably, Lord Mance said that despite the use of phrases such as "reasonable prospect" and "might well produce", he thought there was a real risk that the test described by Lord Sumption would amount to, or be understood as, involving a requirement to establish a prima facie case on the material contained in the specification. In Lord Mance's opinion, the authorities analysed did not put the standard so high.

However, while upholding the approach of the trial judge, and the conclusion of both the lower courts, neither Lord Mance nor Lord Hodge expressly supported the Court of Appeal's statement of principle regarding the test for plausibility.

As noted above, the majority in the Supreme Court disagreed with Floyd LJ's statement of principle that plausibility is a "low, threshold test". In reaching this statement of principle (with which Kitchin LJ agreed), Floyd LJ had considered and drawn upon paragraphs 100-101 of Kitchin LJ's judgment in the Regeneron case and the reasoning of the Supreme Court in Human Genome Sciences v Eli Lilly & Co [2011] UKSC 51. The HGS v Eli Lilly case concerned challenges of lack of industrial application and insufficiency; the Supreme Court treated the approach to the issue of 'plausibility' for each challenge as aligned; the Supreme Court also considered the TBA's reasoning in Johns Hopkins T 1329/04).

A month after the Court of Appeal's judgment in the Warner-Lambert case, the Court of Appeal (again including Kitchin and Floyd LLJ) again considered the test for plausibility in Idenix v Gilead [2016] EWCA Civ 1089. Kitchin LJ gave the reasoned judgment. He also drew upon the Supreme Court's judgment in HGS v Eli Lilly and his own judgment in Regeneron. After quoting Floyd LJ's statement of principle in paragraphs 46-47 of the Warner-Lambert judgment, Kitchin LJ said that the same approach should be adopted when considering in the context of an Agrevo obviousness challenge whether a technical effect is plausible.

In contrast, in its judgment in this Warner-Lambert case, the Supreme Court did not cite or refer to its earlier judgment in HGS v Eli Lilly; nor did it refer to Kitchin LJ's later reasoning. Except for the Court of Appeal's judgment in the Regeneron case (noted above), the only English authority cited was that of Lord Mansfield in Liardet v Johnson (1778), as quoted in Hulme, "On the History of Patent Law", (1902) 18 LQR 280, 285.


Warner-Lambert's claim of infringement was based upon invalid claims 1 and 3, nevertheless the law regarding infringement and its application in the present case were discussed in some depth by each of the Patents Court, the Court of Appeal and the Supreme Court.

At the heart of the dispute lay two questions regarding the interpretation of Swiss form claims:

  1. Is the claimed process confined to the process of manufacturing the goods (i.e. the packaged medicine marketed by the alleged infringers)?
  2. In a Swiss form claim, what does the word "for" actually mean (i.e. what makes an alleged infringer's medicine for the treatment of the claimed indication)?

Unlike the interpretation of the "neuropathic pain" wording in claim 3 of Warner-Lambert's patent, these issues are relevant to all Swiss form claims.

The length of the Swiss form process and contributory infringement under s.60(2) Patents Act

The Patents Court held that the claimed process of the Swiss form claim was confined to the manufacturing process. This had the consequence that no steps taken by a later party involved in prescribing, dispensing or preparing the medicine for administration to the patient (for example by labelling it for use by the patient for the patented indication) could contribute to the fulfilment of the claimed process. Therefore the defendants' marketing of their medicine could not amount to contributory infringement under s.60(2) of the Patents Act 1977 because Actavis could not contribute to the infringement of a claimed process that had already completed.

The Court of Appeal disagreed. Floyd LJ (with whom Kitchin and Patten LLJ agreed) said that "[t]he process of preparing the composition can continue through any packaging step performed by the manufacturer and includes the labelling step performed by the pharmacist". This meant that if the necessary intention regarding the protected indication was present, Warner-Lambert could succeed under s.60(2) (if the patent claims relied upon were valid). Floyd LJ observed that this conclusion was consistent with that reached by the Danish Maritime and Commercial High Court in Warner-Lambert v Krka (25 June 2015).

The Court of Appeal's judgment on this point, albeit obiter, was consistent with its previous judgment on the same point in Actavis v Eli Lilly [2015] EWCA Civ 555. In that case, Eli Lilly's Swiss form claim concerned "pemetrexed disodium". In the ordinary course, before being administered to the patient (but after Actavis' dealings in the packaged medicine had ended), Actavis' pemetrexed containing medicine would be dissolved in and/or diluted in saline, an abundant source of sodium ions. Actavis' packaged medicine was therefore a means relating to an essential element of the invention for the purposes of contributory infringement under s.60(2). This was subsequently confirmed by the Supreme Court as correct, in Actavis v Eli Lilly [2017] UKSC 48 at [111]. Lord Neuberger explained that "[t]he pemetrexed disodium comes into the manufacturing process rather later than it would if the original medicament included pemetrexed disodium rather than pemetrexed dipotassium, but that cannot alter the fact that, before it is administered to the patient, the medicament includes pemetrexed disodium and vitamin B12".

The Supreme Court was unanimous in concluding that the process protected by a Swiss form claim is confined to manufacture for the designated purpose, and does not extend to later steps, for example anything done by the pharmacist. The reasoning of Lord Sumption (with whom Lords Reed, Briggs and Hodge agreed) indicates that the claimed process completes with the packaged product.

This meant that Warner-Lambert's claim for contributory infringement under s.60(2) failed.

The Supreme Court did not cite or refer to its own judgment last year in Actavis v Eli Lilly [2017] UKSC 48, in which Lord Neuberger (with - in that case - whom Lords Sumption, Hodge, Mance and Clark agreed) concluded that the process of the Swiss form claim in Eli Lilly's patent extended to mixing of the (previously) packaged medicine a saline solution for administration by the patient.

What makes an alleged infringer's medicine for the treatment of the claimed indication and s.60(1)(c) infringement

On the question of what makes an alleged infringing medicine for the protected indication, the parties in the Warner-Lambert case were in agreement that some sort of mental element concerning the patented indication was required. At the interim stage, Arnold J held that it required subjective intent on the part of the manufacturer. Following the Court of Appeal's judgment on the interim dispute, in the substantive Patents Court judgment Arnold J adjusted the test a little, suggesting that dispensation of the manufacturer's 'skinny label' product in fulfilment of a generically written prescription on which the pain indication was specified could be enough to satisfy the intent requirement. However on the facts of the case, he concluded that it was not foreseeable that there would be any more than de minimis intent to infringe. Thus Actavis did not have the requisite mental element at the time of first manufacture, and so there was no threatened or later infringement under s.60(1)(c) of the Patents Act by dealings in the medicine in the UK.

Again, the Court of Appeal disagreed. Floyd LJ thought that the judge had fallen into error in seeking to dissect the requirement for intent into that of the doctor, pharmacist and patient. Rather, it was only essential that the manufacturer was able to foresee that there would be intentional use for the claimed medical indication. This was to be distinguished from use where the drug was prescribed for a different indication and, without it being in any sense the intention of the treatment, the claimed indication was in fact treated. Floyd LJ explained that the question for the court was therefore whether the alleged infringer knew or could foresee that at least some of the prescriptions written generically for the active ingredient (pregabalin) for the treatment of the claimed indication would in fact be fulfilled with the defendants' medicine. To the extent liability for infringement was attached to medicines supplied for non-patented purposes, this could be remedied by adjusting the relief awarded by the court.

Floyd LJ noted that a uniform approach on the question of intent in Swiss form claims has not yet emerged in the EPC states. He noted the "only packaging will do" approach adopted by the German courts, but said that the parties in the Warner-Lambert case being in agreement that the word "for" imported a mental element, it could not possibly be the case that the contents of the packaging were the only means of doing this.

The Supreme Court was split on the issue of the meaning of "for" / the mental element of the Swiss form claim.

Throughout the first and second instances and until the end of the hearing before the Supreme Court, it was common ground between the parties that the "for" wording in the Swiss form claim language imported a mental element. The disagreement between them, and between the lower courts, was in the framing of the test for establishing the presence or the absence of the mental element (as well as the outcome of the application of the correct test to the facts of the case). However, in the Supreme Court, Lords Sumption and Reed were of the view that the parties and the lower courts had all been getting this wrong. Instead of a mental element test, they preferred an 'outward presentation' test, drawn from the German jurisprudence and based upon the physical characteristics of the packaged product including its patient information leaflet. Adopting such a test, a 'skinny label' medicine (i.e. one which does not include the patented indication in the list of indications for which it is approved), such as was alleged to infringe in the Warner-Lambert case, would not infringe the Swiss form claim, basically irrespective of its use in practice or the manufacturer's intent in this respect. Lord Sumption considered that this "properly reflects the critical feature of Swiss-form patents, namely that the patent is for the process of manufacture, not for the subsequent use that may be made of the product". Lord Sumption continued ([86]):

"It may be thought anomalous that the manufacturer of the generic product should be free of liability if he markets it for a patent-protected use provided that he labels it as being for a non-protected use. But to my mind it is a far greater anomaly that in a "charade" case the generic manufacturer's intention exposes to liability not just himself but any pharmacist who handles his product even if he scrupulously supplies it only for a non-protected use."

Lords Briggs and Hodge, on the other hand, were of the view that the Swiss form claim language necessarily involves a subjective mental element of some kind on the part of the manufacturer for infringement to be established. In their view, such a test would create a fairer balance between the various policy objectives than would be achieved with Lord Sumption's outward presentation test. Acknowledging that the 'mind' may be a corporate entity, Lord Briggs said ([165]):

"Even if the manufacturer is a corporation using a factory entirely staffed by robots, if the manufacturing process is only protected by the patent if it is carried out for a particular purpose, the requirement to identify a mental element on the part of the manufacturer is simply inescapable. The court is well versed in identifying the governing mind of a corporation and, when the need arises, will no doubt be able to do the same for robots."

Lord Mance noted that so far, the members of the court were equally divided and it was "with some unwillingness" that he pronounced on the issue at all. However, in the obiter consideration of the issues regarding infringement, Lords Sumption, Reed, Briggs and Hodge were all in favour of a conclusion of non-infringement in the present case; the question was where the test should be set in future cases.

Lord Mance's view was that Arnold J's 'subjective intent' test was not the correct approach. He preferred instead Lord Sumption's outward presentation approach, leaving open the question "whether there might be some circumstances in which a generic manufacturer could or should be expected to go further". Like Lord Sumption, he noted that more recent German case law focused less on the external presentation (including the instructions for its use) of the allegedly infringing product, but rather on its inherent suitability for the patented use. Lord Mance summed up his approach as follows ([218]):

"Normally, a generic manufacturer, and it follows others such as doctors, pharmacists and end users, should be protected from infringement of a Swiss-form patent if the manufacturer ensures that the generic product resulting from its manufacturing process is produced, prepared and marketed with a clear limitation to patent-free uses. … a generic manufacturer cannot control the activities of doctors, pharmacists and end users, with which it is in no contractual relationship. The protection afforded by a Swiss-form patent, analysed as protecting a process in the way that English law analyses it, is valuable, but necessarily limited."

Accordingly, the Supreme Court was unanimous in rejecting Floyd LJ's 'reasonable foreseeability' test and apparently supporting the judge's conclusion of no infringement.

What does all of this mean for you?

Well, it remains the law in the UK that a request to amend a patent by re-writing claim language (rather than excising invalid claims) made after a finding of invalidity will usually be refused if a second trial would be required to consider the validity of the new claim. Patent owners litigating or considering litigating their patents should consider in good time before trial the possible outcomes in their case and whether an amendment or conditional amendment application should be filed.

Turning to the issues of substantive patent law in the case, the Supreme Court's judgment in Warner-Lambert v Generics & Anr [2018] UKSC 56 has made it harder for patentees to defend challenges to validity based on lack of plausibility because the standard seems no longer to be a "low, threshold test" (as the Court of Appeal had ruled). The Supreme Court's approach in this respect is likely to impact not just the law regarding sufficiency, but also the applicable tests for Agrevo obviousness, industrial application and priority. Patent claims that include efficacy as a functional technical feature are likely to be most vulnerable in this respect. However, the split nature of the Supreme Court's judgment and the apparent departure from HGS v Eli Lilly [2011] UKSC 51 (albeit without expressly invoking the Practice Statement (Judicial Precedent) [1964] 1 WLR 1234; the effect of which on the Supreme Court was confirmed in Austin v Southwark London Borough Council [2010] UKSC 28), with respect to a principle involved in many aspects of patent law, means that the Supreme Court will likely be asked to revisit the area before too long. Lord Kitchin, alumni of the Patents Court, was sworn in as a Lord Justice of the Supreme Court in October 2018 and could be expected to hear such a case in the future.

On the correct interpretation of the Swiss form process (i.e. whether it is confined to the manufacturing process or extends to later steps taken in a pharmacy, for example labelling or making up for administration to the patient for the treatment of the protected indication), and accordingly on the availability of s.60(2) infringement as a cause of action in respect of sales of packaged medicine, the Supreme Court's departure from its own judgment in Actavis v Eli Lilly [2017] UKSC 48 (again without invoking the Practice Statement) is similarly expected to need a further judgment from the Supreme Court, in a later case, in order to bring clarity to this area of patent law. By Lord Neuberger's sole reasoned judgment in Actavis v Eli Lilly, the Supreme Court unanimously confirmed Actavis' liability for contributory infringement under s.60(2). Hence the reasoning in that case was ratio, Lords Mance, Sumption and Hodge all agreeing with Lord Neuberger. The Supreme Court's four reasoned judgments in this Warner-Lambert judgment were obiter, nevertheless the apparently unanimous reasoning will create a tricky navigational path for the next Supreme Court bench considering the issue.

On the presence (and type) or absence of a mental element in a Swiss form claim, the Supreme Court's reasoning is also obiter. Although formally not binding, obiter reasoning can be persuasive on lower courts and indicates to practitioners the direction of judicial thinking on the relevant point; and this is an area of patent law which has long awaited clarification. The reasoning may also prove applicable for purpose-limited product claims. Yet the Supreme Court's approach raises questions. The majority (Lords Sumption, Reed and Mance) indicated preference for the 'outward presentation' test. This was not an approach advocated by any of the litigants before the first second or third instances, and the parties' submissions and evidence had been prepared accordingly. Rather, the idea seems to have been unilaterally adopted from another legal system (Germany) by some members of the Supreme Court. In paragraph 168, Lord Briggs eloquently notes the risks entailed by this approach, the court lacking understanding of the relevant systems and conditions specific to the other jurisdiction but likely to have influenced the development of the approach in the other jurisdiction.

It is perhaps worth emphasising that in reaching a conclusion of their own accord, the same majority stepped beyond the issues presented to the court by the parties. Such sua sponte rulings (as they are referred to in the US) depart from the general principle underpinning adversarial legal systems that the court is the arbiter of issues presented rather than the inquisitor (see for example Singleton v. Wulff, 428 U.S. 106 (1976) and Hormel v. Helvering, 312 U. S. 552, 312 U. S. 556 (1941)). Such an approach deprives the parties of the opportunity to offer all the evidence they believe relevant to the issues, and also of an instance of appeal. Where the highest court takes this approach, the parties have no instance of appeal. In this Warner-Lambert case, the reasoning was obiter, making no difference to the outcome between the parties; litigants would therefore be well advised to consider in future disputes whether the sua sponte nature of the Supreme Court's ruling on mental element issue may temper its persuasive value.

Finally, practitioners will note that the Supreme Court did not address questions that have arisen in the jurisprudence of the Patents Court and the Court of Appeal, since the Supreme Court's judgment in Actavis v Eli Lilly [2018] UKSC 48, on the correct approach to the interpretation of claim language for the purpose of assessing the validity of a patent. It remains to be settled, for example, to what extent purposive construction remains the test and whether it may include consideration of equivalents.

So the Supreme Court's long awaited judgment in the Warner-Lambert case has given commentators plenty to discuss, but it is unlikely to have put to rest many of the issues upon which it ruled.

It is perhaps ironic that the House of Lords authority cited by Lord Briggs in respect of ambiguity in claim language (Parkinson v Simon (1895) 12 RPC 403) is also authority for the proposition that:

"The practice of giving decisions (which only amounted to dicta) on issues not necessary to decide on appeal was not to be recommended, and will not be adopted by the House."

The Supreme Court's judgment in Warner-Lambert v Generics & Anr [2018] UKSC 56 (14 November 2018) is available here.

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