The UK Supreme Court has handed down its judgement in Warner-Lambert v Generics & Anr [2018] UKSC 56 in which the issue of plausibility was considered in-depth. The Supreme Court unanimously held that broad medical treatment claims were invalid, with the majority finding that the requirement of plausibility is not a low, threshold test. This approach is somewhat at odds with that adopted by the Australian Patent Office in Evolva SA [2017] APO 57, which relied upon earlier UK case law.


The UK Supreme Court recently delivered their decision on a long-running dispute between Pfizer (parent company of Warner-Lambert) and Generics (UK) Ltd (trading as Mylan) and Actavis Group. The dispute concerned the validity and infringement of Warner-Lambert’s patent which covered “second medical use” (Swiss-style claim) protection of the drug, pregabalin. Claim 1 and dependent claims 2 and 3 were principally relevant and are as follows:

  1. Use of (S)-3-(aminomethyl)-5-methylhexanoic acid or a pharmaceutically acceptable salt thereof for the preparation of a pharmaceutical composition for treating pain.
  2. Use according to Claim 1 wherein the pain is inflammatory pain.
  3. Use according to Claim 1 wherein the pain is neuropathic pain.

The patentability requirement of sufficiency (and the related concepts of enablement and plausibility) ensures that the monopoly granted by a patent extends only to that which could reasonably be said to be disclosed in the patent specification and no further. The sufficiency requirement is found in section 14(3) of the UK Patents Act 1977 which states “[t]he specification of an application shall disclose the invention in a manner which is clear enough and complete enough for the invention to be performed by a person skilled in the art.” A patent may be revoked on the grounds that the invention is insufficiently disclosed under section 72(1)(c).

Actavis marketed a pregabalin generic under the brand name “Lecaent”. In 2014, Actavis and Mylan separately sought revocation of Warner-Lambert’s patent on the grounds of insufficiency. Warner-Lambert commenced infringement proceedings against Actavis later in the same year. Arnold J of the High Court held claims 1 and 3 to be insufficient and that even if the claims are valid, they are deemed not infringed. It was further ruled that a post-trial amendment lodged by Warner-Lambert to limit the claims to valid subject matter would amount to an abuse of process and was thus rejected. Warner-Lambert’s appeal in 2015 was unsuccessful as, broadly, the Court of Appeal upheld the decision of the High Court.

The judgement of the Supreme Court was handed down on 14 November 2018 for which inter alia issues of insufficiency and infringement of Swiss-style claims were considered. Here, we will discuss the ruling on plausibility in detail.

The Supreme Court’s Decision

The Supreme Court unanimously agreed that it was implausible that pregabalin would be effective at treating any type of pain (claim 1) and all neuropathic pain (claim 3) including peripheral and central pain.

However, the Lords were split on their views of what the appropriate test for plausibility should be. The majority of the Supreme Court (Lord Sumption, Lord Reed and Lord Briggs) disagreed with the Court of Appeal’s statement that:

The EPO and domestic cases do, however, indicate that the requirement of plausibility is a low, threshold test. It is designed to prohibit speculative claiming, which would otherwise allow the armchair inventor a monopoly over a field of endeavour to which he has made no contribution. It is not designed to prohibit patents for good faith predictions which have some, albeit manifestly incomplete, basis. Such claims may turn out to be insufficient nonetheless if the prediction turns out to be untrue. A patent which accurately predicts that an invention will work is, however, not likely to be revoked on the ground that the prediction was based on the slimmest of evidence. Thus, the claims will easily be seen not to be speculative where the inventor provides a reasonably credible theory as to why the invention will or might work. The same is true where the data in the specification is such that the reader is encouraged to try the invention”.

Turning to some of the observations of the majority of the Supreme Court, it was stated by Lord Sumption:

Without some disclosure of how or why the known product can be expected to work in the new application, it would be possible to patent the manufacture of known compounds for the purpose of treating every conceivably relevant condition without having invented anything at all, in the hope that trial and error might in due course show that the product was efficacious in treating at least some of them…[t]he patentee must disclose some reason for regarding this assertion as “plausible”. (emphasis added); and

“The Court of Appeal’s statement of the effect of the plausibility test has already been quoted (para 20 above). They considered that the threshold was not only low, but that the test could be satisfied by a “prediction … based on the slimmest of evidence” or one based on material which was “manifestly incomplete”. Consistently with that approach, they considered (paras 40, 130) that the Board’s observations in SALK laid down no general principle. I respectfully disagree. The principle is that the specification must disclose some reason for supposing that the implied assertion of efficacy in the claim is true. Plausibility is not a distinct condition of validity with a life of its own, but a standard against which that must be demonstrated. Its adoption is a mitigation of the principle in favour of patentability. It reflects the practical difficulty of demonstrating therapeutic efficacy to any higher standard at the stage when the patent application must in practice be made. The test is relatively undemanding. But it cannot be deprived of all meaning or reduced, as Floyd LJ’s statement does, to little more than a test of good faith. Indeed, if the threshold were as low as he suggests, it would be unlikely to serve even the limited purpose that he assigns to it of barring speculative or armchair claims.” (emphasis added)

Applying the test for plausibility as Lord Sumption had described it, the majority were not satisfied that efficacy in peripheral neuropathic pain was plausible. Notably, 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.”

In contrast, the minority of the Supreme Court (Lord Hodge, with whom Lord Mance agreed) thought Lord Sumption has set the standard for plausibility too high. Lord Hodge said, “I do not interpret those principles as requiring the patentee to demonstrate within its patent a prima facie case of therapeutic efficacy”.

As explained by Lord Hodge:

“Adopting the lower standard of plausibility which the recent decisions support, I am inclined to think that Arnold J, who heard and analysed the expert evidence on this matter, including that of Professor Woolf, Dr Scadding and Professor Wood, did not err in his evaluation of that evidence when he concluded that Warner-Lambert had done just enough to satisfy the plausibility test in relation to peripheral neuropathic pain. The result of the rat paw formalin test demonstrated that pregabalin reduced inflammatory pain at phase 2. There was expert evidence which treated as credible the suggestion that the efficacy of pregabalin in reducing pain which that test revealed would not be confined to inflammatory pain and that the medication would also be effective in relation to peripheral neuropathic pain. As Arnold J stated (para 351), it was common general knowledge that central sensitisation was involved (at least as an amplifying mechanism) both in relation to inflammatory pain and in relation to peripheral neuropathic pain and that it played a role in the rat paw formalin test. The patent had not demonstrated that pregabalin had an effect on central sensitisation and a prima facie case had not been made out. But the plausibility test does not require that standard.” (emphasis added)

Nevertheless, Lords Hodge and Mance agreed with the majority that claim 3 did not satisfy the standard for plausibility in respect of the central neuropathic pain.

Implications for Australia

In Australia, since 15 April 2013 (Raising the Bar Amendment) a specification must disclose the invention in a clear enough and complete enough manner to enable performance by a person skilled in the relevant art (section 40(2)(a)).

According to the Explanatory Memorandum to the Intellectual Property Laws Amendment (Raising the Bar) Bill 2011 (Cth), the purpose of the change of law was to require enablement across the full width of the claims, while adopting language that is consistent with that used in other jurisdictions. The wording in section 40(2)(a) is similar to section 14(3) of the UK patents legislation and Article 83 of the European Patent Convention.  The intention is that paragraph 40(2)(a) be given, as close as is practicable, the same effect as the corresponding provisions of UK legislation and the European Patent Convention.

Although it is clear that Australian courts are not bound to follow UK or European legal precedent, the courts often seek guidance from the approach used and case law from UK and Europe. Since Parliament has explicitly indicated that the new enablement requirement is intended to align with UK law, it seems even more likely that the Australian Courts will consider UK case law on this topic carefully. While there have not been any Court decisions on the new enablement requirement in Australia yet, the Patent Office recently issued a decision in Evolva SA [2017] APO 57 (the Evolva decision) which considered the importance of plausibility and whether an invention would work across the scope of the claim.  In this regard, the Evolva decision agreed with the Court of Appeal’s interpretation that the requirement of plausibility is a low threshold test and may be based on the slimmest of evidence. The Evolva decision further drew reasoning from another UK decision (HGS v Eli Lilly & Co [2011] UKSC 51) where Lord Neuberger stated that in some cases a “reasonably creditable” claimed use or “educated guess” can suffice.

As noted above, the majority in the Supreme Court disagreed with the principle that plausibility is a “low, threshold test”.  Given the precedent established by the Australian Patent Office in following earlier UK law for plausibility and the statements to this effect in the Explanatory Memorandum, we would anticipate that an Australian court would carefully consider the Supreme Court’s decision, despite the Lords being split on the relevant test for plausibility.

Authored by Michael Christie, PhD

The purposes of the claims of a patent are to define the metes and bounds of an invention, and to place the public on notice of what constitutes an infringement. Generally speaking, the requirements for patent claims are that they must:

  • define the matter for which protection is sought, preferably in terms of the “technical features of the invention”,
  • be clear and concise/succinct, and
  • supported by matter disclosed in the specification, and enabled across their full scope.

There are arguably only 2 basic types of patent claim:

  1. claims to a physical entity (e.g., compound, product, apparatus) and,
  2. claims to an activity (e.g., process, use).

For many inventions, claims in more than one category are needed for full protection. In the field of chemical sciences (meaning chemical compositions such as those arising in the fields of chemistry, materials science, petrochemicals, pharmaceuticals, and biotechnology), to properly protect the invention a patent may protect any one or more of the following subject matter:

  • a compound, which may be defined as a class of compounds, as a specific compound, or group of specific compounds,
  • a composition containing the compound,
  • an article made from, or containing the compound,
  • a process for preparing the compound (and the compound when prepared by the process),
  • a composition when used in a particular manner or under some defined circumstances (generally understood as a pseudo method claim),
  • a compound for treating a medical condition,
  • a method of using a compound for a specific purpose (e.g., for curing a polymer composition), or for treating a medical condition (a method of treatment claim), and
  • the use of a compound in the manufacture of a medicament for treating a medical condition (known as “Swiss style” claims).

Another common claim type is a claim to a kit, which either comprises a novel component (compound or composition), or is constructed to ensure that the kit components are applied simultaneously/sequentially to produce a new product or synergistic affect, or the kit limited to use in a novel and inventive method.

In the field of biotechnology, patentable subject matter includes isolated naturally-occurring micro-organisms, peptides, or proteins, and (under some limited circumstances) gene sequences. Patent claims can therefore be directed to one or more of these categories, too. For protein-type inventions claims can be directed to a nucleic acid encoding the protein, a vector containing the nucleic acid, and a host cell comprising the nucleic acid or vector.

Depending on the circumstances, there are a myriad of other claim types that can be pursued. For example, claims to a precursor or an intermediate (e.g., such as a pre-polymer) may be appropriate. In another example, claims could be directed to a solution that has some specific use. For example, a copper electroplating solution that comprises a solution of copper sulfate, sulphuric acid, and wherein the pH has been adjusted to a specific range.

In another example, the invention may lie in methods of identifying compounds that achieve a certain technical effect (e.g., A binding assay for detecting one or more specific analyte(s) in a sample), or may lie in the particular spatial configuration of entities of a mixture (e.g., one entity may be an immediate release phase and the other entity may be a prolonged release phase).

Closing comments

In the field of chemical sciences (e.g., chemistry, materials science, petrochemicals, pharmaceuticals, biotechnology, etc) to protect an invention one or more different types of patent claims may be required.  The choice of claim types depends on the invention at hand, under what circumstances there may be infringement, who may license the patent, and should ultimately align with the applicant’s commercial objectives.

Outlined in this article is a summary of the main types of claims that are pursued when drafting a patent application in the chemical sciences field. It is impossible to foreshadow all the types of patent claims that may be pursued, and thus when an idea is an important commercial asset, it is wise to engage a qualified patent attorney to assist in the generation of relevant intellectual property rights that suitably protect that commercial asset. At Shelston IP, we have a number of highly experienced attorneys who can assist in navigating these complexities.

The content of this article is general in nature and must not be relied on in lieu of advice from a qualified professional in respect of your particular circumstances.

Authored by Michael Christie, PhD

In this, the first of a trilogy of articles investigating specific areas of Australian Patent Office examination practice, I consider how the High Court’s decision in D’Arcy v Myriad Genetics Inc [2015] HCA 35 (7 October 2015) (the Myriad decision) has been interpreted to render all non-naturally-occurring cDNA compositions patent ineligible. I also question the legitimacy of this current Patent Office practice in view of patent eligibility standards applied to other gene-based inventions.


When the High Court of Australia ruled against the patentability of isolated human genes in October 2015, biotechnology stakeholders were on tenterhooks as to how the decision would be interpreted and its impact on Australian biotechnology innovation.

It is now history that the Australian Patent Office’s narrow interpretation of the Myriad decision manifested only as an exclusion to patentability of isolated gene sequences encompassing “genetic information” that occurs in nature. Isolated naturally-occurring material other than genes, such as proteins and micro-organisms, remain unquestionably patent eligible under Australian law.  This contrasts with the US situation, where the Supreme Court “Myriad decision” resulted in a patentability exclusion for all isolated naturally-occurring materials.

Remarkably, however, up until the Myriad decision’s first anniversary, the Australian Patent Office implemented examination practice that excluded from patentability certain gene-based inventions that only came about as a result of human activity.  These inventions included codon-optimised nucleic acid sequences, and double-stranded interfering RNA compositions. The Patent Office’s rationale at the time was that although such compositions do not occur in nature, they encompass “genetic information” that is naturally occurring. This practice was reconsidered by the Patent Office in Cargill Incorporated v Dow AgroSciences LLC [2016] APO 43 (5 July 2016) (the Cargill decision), which confirmed the patentability of codon-optimised nucleic acid sequences) and Arrowhead Research Corporation [2016] APO 70 (13 October 2016) (the Arrowhead decision), which confirmed the patentability of interfering RNA compositions.

Australian Patent Office practice, however, currently maintains a patentability exclusion for all cDNA inventions.  It is, however, arguable whether this practice is consistent with the Patent Office’s own precedents set down by the Cargill and Arrowhead decisions.

cDNA: the current Patent Office position

According to the Australian Patent Office Manual of Practice and Procedure, if “genetic information” in a man-made molecule, for example cDNA, is the same as that in the genome, the molecule is not patent eligible”.  cDNA appears to have been specifically excluded from patentability because the Myriad decision states in obiter at paragraph 55:

The information stored in “… the sequence of nucleotides coding for the mutated or polymorphic BRCA1 polypeptide is the same information as that contained in the DNA of the person from which the nucleic acid was isolated. …. That characteristic also attaches to cDNA, covered by the claims, which is synthesised but replicates a naturally occurring sequence of exons”.

Based on this paragraph, which specifically concerns a prognostic invention and not the expression of a protein, the Patent Office has applied a broad exclusion to the patentability of all cDNA inventions.

cDNA consists of a nucleotide sequence of human-made fused exons (the exons encoding a protein), without intervening non-coding introns.  It is well known by molecular biologists that the removal of introns confers a multitude of advantages not exhibited by the corresponding genomic sequence, including ease of cloning and manipulation, and superior protein expression levels. Moreover, it is well understood that intron sequences include genetic information. This is a fact clearly identified by the Myriad decision at paragraph 201, where it is stated “[i]ntrons do not encode a protein but they contain information that helps regulate the utilisation by the cell of the encoded information in the exons”. Based on this point alone, it would seem clear that if a cDNA invention relates to the expression of a protein, cDNA could not be considered as encompassing the same information as that which occurs in nature.

Patent Office practice inconsistencies?

Most recently, I challenged the Patent Office’s position in a case where the claimed cDNA demonstrably exhibited commercial advantages over the corresponding genomic sequence. The Patent Office acknowledged that the claimed cDNA provided advantages which distinguished it from genomic genetic information. The relevant claims, however, were ultimately rejected because the Examiner formed a view that “[t]he key issue is that in the absence of an appropriate vector, isolated cDNA is in substance genetic information which encodes the same polypeptide as the genomic sequence” The Examiner also stated that the benefits of “efficiency and ease of expression or quantity of expression, arise as a result of a man-made expression construct and expression in a transgenic host”. This approach is arguably inconsistent with the position of the Patent Office in the Cargill decision, where the patentability of codon-optimised DNA was confirmed based on its utility. Relevantly, all of the points raised by the Examiner above, to support a case of patent ineligibility, also clearly apply to patent eligible codon-optimised DNA.

Specifically in the Cargill decision, the Delegate stated that codon-optimisation is an important man-made variation to the naturally occurring sequence, notwithstanding that such sequences code for the same protein as a naturally occurring sequence, because it facilitates optimal production of the encoded protein in certain cells above that which could be expected from the naturally-occurring sequence.  Such benefits, however, only come about as a result of an expression construct and expression in a transgenic host, which are the identical circumstances that confer the commercial advantages associated with cDNA.

Similarly, in the Arrowhead decision, it was found that the double-stranded nature of the claimed RNA compositions played a significant role in the working of the invention.

In both Cargill and Arrowhead cases, it was the advantages and economic utility of the claimed nucleotide sequences which provided basis for their patentability. However, the advantages and economic utility of cDNA sequences, which are directly comparable to codon-optimised sequences, are currently insufficient to confer patentability to cDNA inventions.


It is difficult to understand how Applicants claiming cDNA inventions that confer significant economic advantages over naturally-occurring sequences are receiving fair treatment from the Patent Office given that codon-optimised DNA sequences, which exhibit similar advantages, are patent eligible. Hopefully, in the future the Patent Office will have the opportunity to consider patent eligibility of cDNA in greater detail to ensure that consistent examination practice is clearly applied.

Authored by Michael Christie, PhD