The Singapore Court of Appeal Rules on Post Grant Amendments to Patents and Validity of Second Medical Use Claims

On 1 August 2017, the Singapore Court of Appeal in Warner-Lambert Company LLC v Novartis (Singapore) Pte Ltd [2017] SGCA 45 dismissed Warner-Lambert’s application to amend its patent for the use of pregabalin for the treatment of pain (the “Patent”).


On 21 April 2015, Warner-Lambert commenced an action against Novartis in Singapore for infringement of its Patent. Novartis filed a defence and counterclaim seeking revocation of the Patent on the ground that the Patent was invalid as it claimed a monopoly over methods of treatment of the human or animal body, something impermissible under Singapore’s patent law. Warner-Lambert thereafter applied for leave to amend the Patent to cure the invalidity in the Patent’s granted claims.

It is useful to note that Singapore’s patent system was a self-assessment system. Under this self-assessment system, the Intellectual Property Office of Singapore (“IPOS”) did not conduct an independent search and examination to determine if the invention was patentable. Instead, the burden was on the applicant to self-certify the patent’s compliance with the patentability requirements under the Patents Act. On 14 February 2014, the self-assessment system was replaced by a “positive-grant” system which remains in force today. Under the “positive-grant” system, IPOS makes a positive determination on whether the patent application complies with the patentability of the Patents Act.

Of importance to this judgment was the fact that Warner-Lambert’s Patent was filed under the self-assessment system.

The Court’s Exercise of Discretion to Allow Post-Grant Amendments

The decision is a timely reminder that the power to allow a post-grant amendment of patents pursuant to section 83 of the Patents Act, when parties are in the midst of court proceedings, is a discretionary one. The Court of Appeal stressed that even if the amendment does not disclose additional matter or extend the protection conferred by the patent, it retains the general discretion to refuse an amendment application.

Applying Smith Kline & French Laboratories Limited v Evans Medical Limited [1989] FSR 561, the Court of Appeal held that Warner-Lambert had unduly delayed in seeking the amendments for more than a decade. Notwithstanding the long delay indicating that it was an unreasonable one, the Court noted that Warner-Lambert had obtained an International Preliminary Examination Report from the European Patent Office acting as an International Preliminary Examining Authority under the Patent Cooperation Treaty which stated that “[c]laims directed to methods of treatment of the human or animal body by therapy might be found inadmissible in some patent systems” in February 1998. In December 1998, Warner-Lambert filed the Patent’s corresponding European application with an accompanying amendment to the claims from method of treatment claims to Swiss-style claims, but did not do the same for the Patent in Singapore. In addition, Warner-Lambert had also amended some of its other Singapore patent applications pre-grant from method of treatment claims to Swiss-style claims in 2005, 2007, and 2008. Accordingly, the Court of Appeal, stating that the appropriate juncture to question whether the amending party has been guilty of an unreasonable delay is the time it was first made aware of the need to amend, found that Warner-Lambert had known or ought to have known that the Patent was problematic but had chosen not to take any steps to find out more or to amend the Patent.

Further, the Court of Appeal emphasized that a strict approach was adopted as the Patent had been granted under the self-assessment system. Patentees under the self-assessment system are under an obligation to make a considered decision before proceeding to obtain a grant of the Patent, and should not be given the liberty of taking a lackadaisical approach in ensuring compliance with the requirements of patentability. The Court of Appeal further opined that a lenient approach would only encourage dilatory conduct and wilful blindness on the part of the patentees.

In addition to the unreasonable delay in seeking the amendments to the Patent, the Court of Appeal also held that a patent granted under the self-assessment system which is obviously invalid in its totality, and where such invalidity is attributed solely to the patentee, such invalidity would be fatal to any amendment application. As the Patent is obviously invalid as it claims a method of treatment, it confers no protection whatsoever. Thus, the Court of Appeal thus held that Warner-Lambert’s amendment application sought to validate that which is not valid from the beginning.

Validity of Swiss-style Claims and Subsequent Medical Use Claims

Recognising that the validity of Swiss-style claims has yet to be considered by the Singapore courts, the Court of Appeal, in obiter dicta, adopted a liberal interpretation of section 14(7) of the Patents Act, which mirrors section 2(6) of the UK Patents Act 1977, and opined that it recognises new uses of known substances as long as the new uses do not form part of the state of the art. In coming to its opinion, the Court of Appeal diverged from the English jurisprudence, and was of the view that the words “any such method” refer to a “method of treatment of the human or animal body by surgery or therapy or of diagnosis practised on the human or animal body” in the earlier half of the provision, and that in no way prevents section 14(7) from bearing the meaning that any use, first of subsequent, which is not part of the state of the art, is novel. If this wider interpretation is adopted, the Court of Appeal remarked that there would be no need to resort to Swiss-style claims, which involve, as observed by the High Court judge, a “fiction (implicit) behind the finding of novelty in the method of manufacture on the basis of a new therapeutic use“.

The Court of Appeal also recognised that there are certain practical difficulties in recognising Swiss-style claims and enforcing them in infringement actions: the law is struggling to balance rewarding the patentee for elucidating a new use for the drug, whilst not excluding competing manufacturers from making and marketing the drug for its known purpose (as observed by Floyd LJ in Warner-Lambert Company LLC v Generics (UK) Ltd (trading as Mylan) and others [2016] EWCA Civ 1006). However, the Court stated that if their interpretation of section 14(7) is given the meaning discussed above, the novel and perhaps questionable use of Swiss-style claims to get around the perceived meaning of section 14(7) will no longer be necessary; a purpose-limited product claim in the form of “Compound X for use in the treatment of disease Y” would suffice.


The first key takeaway, namely the exercise of the Court’s discretion to allow post-grant amendments and more specifically on the factor of undue delay, is a timely reminder for patentees in Singapore to make any such amendment where necessary expeditiously. This would be more pertinent where the patent in question was granted before 14 February 2014, under Singapore’s then self-assessment regime.

Second, as regards Swiss-style claims and subsequent medical use claims, while the Court of Appeal did caveat that parties had not made full arguments on this issue, it is clear that the Court is prepared to adopt a wider interpretation of section 14(7) in order to allow subsequent medical use claims. However, whether or not the Court will validate Swiss-style claims remains uncertain given that the Court had opined that the use of Swiss-style claims is questionable and rest on a legal fiction. Nevertheless, it appears that subsequent medical use claims will be accepted and patentable in Singapore as a purpose-limited product claim.