02:47 PM Victor Looi (LLB, BBM(Finance), Singapore Management University)

    The Amendment of Patent Claims, Protection of Subsequent Medical Uses, and Validity of Swiss-Style Claims



    In the recent decision of Warner-Lambert Company LLC v Novartis (Singapore) Pte Ltd [2017] SGCA 45, the five-judge Court of Appeal (the “CA”) examined two issues in patent law which had hitherto received scant mention by the local courts, viz, whether subsequent medical uses of known substances were protected under the Patents Act (the “Act”), and whether Swiss-style claims (i.e., purpose-limited process claims) were valid under the Act. To assist the CA with the said issues, amongst others, the esteemed Professor David Llewelyn was appointed as amicus curiae. While the CA’s eventual observations regarding these novel issues were obiter, they nevertheless provide some guidance and clarity to patent applicants as to how to draft claims that can more effectively protect the applicants’ inventions. 


    Warner-Lambert Company LLC (the “Plaintiff”) is a pharmaceutical company that owned a patent for the use of a substance known as pregabalin for the treatment of pain (the “Patent”). This Patent was filed in July 1997 and subsequently granted in Singapore on May 2000.

    In March 2015, the Plaintiff was notified of Novartis (Singapore) Pte Ltd’s (the “Defendant”) application to the Health Sciences Authority for product licences for pregabalin products. The Plaintiff then commenced a suit, seeking, amongst others, a declaration that the Defendant would be infringing the Patent if it carried out the acts that the product licences were sought for.

    In response, the Defendant filed its defence and counterclaim, seeking to revoke the Patent because it claimed protection over a method of treatment of the human or animal body, which was not patentable under Singapore law (see s. 16(2) of the Act).

    Subsequently, the Plaintiff applied for leave to amend the Patent in August 2015, from a method of treatment claim to a Swiss-style claim, to cure the invalidity therein.

    The trial judge, George Wei J, dismissed this application on the basis that (a) allowing the amendments would widen the scope of protection of the Patent, which would violate s. 84(3)(b) of the Act; and (b) such amendments were only sought for after an undue and inexplicable delay by the Plaintiff.

    This decision by the High Court prompted the Plaintiff to appeal to the CA.


    On a preliminary note, the CA pointed out that s. 83(1) of the Act allows the Court the discretion to refuse an amendment of patent specifications, even if the amendment does not widen the scope of protection conferred by the patent or disclose additional matter. The Court, in exercising such discretion, would take into account various factors, including whether the patentee delayed in seeking the amendment and whether he had sought to obtain an unfair advantage through the amendment.

    Delay in seeking amendments

    The CA first recognised that the Plaintiff’s delay in seeking amendments was for more than 10 years.

    Meanwhile, no reasonable explanation was proffered by the Plaintiff for such a delay. Instead, there was evidence that the Plaintiff knew or ought to have known about the defects in its Patent but had decided not to investigate into or to amend the Patent’s claim. For instance, the Plaintiff had started to adopt measures in other jurisdictions many years ago to remedy the potential invalidity arising from their method of treatment claims.

    Because of the Plaintiff’s unreasonable delay in seeking amendments, the CA concurred with Wei J’s decision to disallow the proposed amendments on the said basis.

    Scope of protection of patent

    Additionally, the CA held that it would disallow the proposed amendments, since the Patent was obviously invalid in its totality. In a self-assessment system, the onus was on a patentee to ensure that his patent was valid, given the monopoly rights that he could enjoy as a result of the patent protection. In the present case, the Plaintiff had clearly failed to do so.

    Also, the proposed amendments would change the scope of protection from the method of treatment using pregabalin to the manufacture of pregabalin for treatment purposes. This would amount to an extension of the scope of protection, which was prohibited under s. 84(3)(b) of the Act.

    Novel issues

    The CA stated that subsequent medical uses could be protected under s. 14(7) of the Act, which provides that “[i]n the case of an invention consisting of a substance or composition for use in a method of treatment of the human or animal body …, the fact that the substance or composition forms part of the state of the art shall not prevent the invention from being taken to be new if the use of the substance or composition in any such method does not form part of the state of the art” (emphasis added). In the CA’s view, the term “use” could be given a wider and purposive interpretation, to include subsequent uses of the substance or composition for medical treatment. This is in contrast with the narrower interpretation that the English courts have accorded to the term “use” in the equivalent provision in England, viz, the first use only.

    Based on the CA’s interpretation, patent applicants may then couch their claims in the form of purpose-limited product claims, which can be admissible in Singapore by virtue of s. 16(3) of the Act. This may obviate the need for applicants to rely on Swiss-style claims during drafting.

    Notwithstanding such comments, the CA proceeded with examining the validity and relevance of Swiss-style claims in Europe and the United Kingdom. In brief, the CA pointed out that while such claims are recognised in Europe and United Kingdom today, they have become less pertinent than before. This is because of the changes to the European Patent Convention and the enactment of the UK Patents Act, which now confer protection for subsequent medical uses via purpose-limited product claims.

    The CA concluded by stating that while Swiss-style claims are permitted by the Intellectual Property Office of Singapore (“IPOS”), they are but “a novel and perhaps questionable way” of protecting subsequent medical uses, which could otherwise be addressed by adopting the wider interpretation of s. 14(7) (see [96]).


    Scope of protection of patent

    The CA distinguished at [62] between a patent that was invalid because its claim was prohibited and a patent that was invalid due to anticipation by prior art, and stated that in the former case, because the patent failed to meet the criterion for patentability, such invalidity would be fatal to an amendment application. Critics might argue that based on this reasoning (which they disagree with), a patent in the latter case, viz, one that is anticipated by prior art, would be no different from a patent in the former case. The fact that a patent is anticipated by prior art means that it never satisfied the patentability requirement of novelty ab initio. Therefore, it should similarly follow that such invalidity would be fatal to any amendment application for patents that are anticipated by prior art.

    Detractors might also argue that the proposed amendments to the Patent, strictly speaking, would not extend the protection conferred by the Patent. To say that there would be an extension of such protection presumed that there was protection to begin with. However, since the method of treatment claim was invalid, such protection was absent ab initio. It thus followed that there could be no extension of something which never existed in the first place. Accordingly, the prohibition under s. 84(3)(b) could not apply to preclude an amendment of the Patent. 

    It is submitted that proponents of this argument are reading too deep into s. 84(3)(b). Such an argument is unlikely to comport with Parliamentary intention of precluding applicants from amending claims to expand the monopoly arising from their claims. Also, even if this argument were accepted, the Court, as rightly pointed out by the CA, has discretion in disallowing amendments, notwithstanding that no provisions in s. 84(3) have been contravened.

    Another point of contention that opponents may have is that while the Plaintiff may have sought to obtain an advantage from the amendment of the Patent, such advantage was not unfair for two reasons.

    First, any third party seeking to use pregabalin would, upon identifying the Patent, have immediately known that the Patent was invalid because it comprised a method of treatment claim. On this basis, the third party could just have applied to revoke the Patent, or have proceeded with using pregabalin for medical treatments without fear of being liable for infringement. Therefore, it could not be said that the Plaintiff had been enjoying a monopoly from the date the Patent was registered.

    Next, allowing the Plaintiff to amend its claim and to enjoy protection for the remaining period would not unduly prejudice the Defendant’s interests. This is because when the Defendant sought to revoke the Patent, the Patent’s statutory protection was already expiring in less than 3 years. Also, the Patent would have expired shortly after the matter was heard before the CA, and the Defendant would thereafter be able to proceed with obtaining product licences for pregabalin products with ease.

    Such assertions, however, can be refuted. The brevity of the remaining period of protection sought by the Plaintiff is inconsequential since the Patent should never have been granted and the Plaintiff should not be allowed to enjoy protection that it did not deserve in the first place. By allowing the Plaintiff to rectify its mistake, the CA would be condoning the Plaintiff’s expansion of its monopoly at the expense of the Defendant, notwithstanding the Plaintiff’s severely flawed claim. Additionally, as rightly recognised by the CA, to allow the amendment just because the original and amended claims pertain to the same product “would effectively make nonsense of the prohibition against method of treatment claims in s 16 of the Patents Act” (see [74]).

    Novel issues

    Previously, the local courts did not have the opportunity to consider the ambit of s. 14(7) of the Act, and whether it extended to protect subsequent medical uses of substances (Susanna Leong, Intellectual Property Law of Singapore (Academy Publishing, 2013) at [16.160]). Therefore, the CA’s efforts in the present case to address this novel issue, notwithstanding that its decision did not turn on such, are timely and commendable.

    However, the wider interpretation accorded to s. 14(7) is potentially controvertible. Opponents may point out that since s. 14(7) was modelled based on s. 2(6) of the UK Patents Act 1977, the local courts should be slow to depart from the UK courts’ interpretation of the equivalent provision, i.e., s. 14(7) should be read to apply only to the first medical use of substances or compounds. If the Singapore Parliament had intended for subsequent medical uses to be protectable under the Act, they would have replaced s. 14(7) with provisions that mirror s. 4A of the UK Patents Act 2004 (see s. 4A(3) and s. 4A(4)) more closely, i.e., have separate provisions protecting the first and the subsequent medical uses of substances or compounds. In fact, Parliament had multiple opportunities to make such changes in the numerous amendments made to the Act from 2005 to 2016 but chose not to. Therefore, according to detractors, it would not cohere with Parliamentary intention to adopt a strained interpretation of s. 14(7).

    If such an assertion were accepted, then purpose-limited product claims could only be valid in Singapore (subject to other patentability requirements being fulfilled) if the purpose stated was the first medical use of the product.  To protect subsequent medical uses of the product, prospective applicants would then have to rely on Swiss-style claims instead.

    It is recognised that difficulties may arise from the use of Swiss-style claims. They range from the broader concern of how to strike a balance between the two policy considerations (see [94]), to the more specific concern of whether dosage claims (e.g. the use of substance x for the preparation of a medicament for the treatment of y and where the dosage amount is z mg) are considered as Swiss-style claims or are, in substance, method of treatment claims which are prohibited (Leong, Intellectual Property Law of Singapore at [16.154]). In response to such difficulties, critics may assert that it is up to the local courts to give clarity to these issues rather than to sweep them aside and rely on a wider interpretation of s. 14(7) as an alternative route. While such an interpretation could be beneficial in spurring medical research into new uses of substances or compounds, until Parliament amends s. 14(7) to explicitly cover subsequent medical uses, the position should remain that s. 14(7) only protects first medical uses of substances or compounds, to give effect to Parliamentary intention.

    Key takeaways

    Notwithstanding the abovementioned arguments that critics may assert, it is submitted that there are several key takeaways from this case worth bearing in mind. 

    First, the fact that the Plaintiff could procure patent protection for a claim, despite its invalidity, shows a foible in the self-assessment patent system. Accordingly, the recent switch to a positive grant patent system is a timely move in the right direction. This is because it can provide greater assurance to the public that the patents on the register have passed rigorous examination by the IPOS and have satisfied the patentability criteria. This adds clarity to the ambits within which other industry players may operate. Simultaneously, having a positive grant system may reduce the number of patent revocation actions initiated in the local courts, thereby saving costs for parties, which could be channeled to more productive uses.

    Secondly, prospective patentees should seek legal advice regarding the validity and strengths of their patent claims ideally before applying for patent protection, or if not, expeditiously after the registration of their patents. This is to ensure that any potential invalidities in their claims are identified and rectified expeditiously through a Request to Amend Application Before Grant (see Patents Form 13 on the IPOS website) or an Application to Amend Specification After Grant (see Patents Form 17 on the IPOS website). A failure to do so might result in the Court precluding the patentee, in a revocation action against the patentee, from amending the claim because of undue delay. Additionally, parties owning multiple patents which cover the same subject matter across jurisdictions should ensure they have coordinated efforts to review (and if necessary, amend) their claims across these jurisdictions upon discovery of a defect in one of their patent claims.

    Finally, prospective patentees can consider phrasing their claims as purpose-limited product claims because the subsequent medical uses of the products, in light of the comments by the highest court of the land, appear to be protectable under the Act for the time being. Alternatively, patent applicants can rely on Swiss-style claims since such claims are allowed by IPOS (see [96]).  

    * This blog entry may be cited as Victor Looi, “The Amendment of Patent Claims, Protection of Subsequent Medical Uses, and Validity of Swiss-Style Claims”  (16 August 2017) (

    ** A PDF version of this entry may be downloaded here

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