Prior to 2023, the Singapore Court recognised only one type of insufficiency called “classical insufficiency”. Simply put, a patent is a quid-pro-quo. In return for a monopoly of 20 years, the patentee must teach its invention to the public. If the teachings do not allow a person skilled in the art to perform and/or recreate the invention, then the patentee should not be entitled to the monopoly and the patent must be revoked.

Statistically, in Singapore, patents are rarely invalidated on the basis of insufficiency. Even if the defendant is able to establish some gap in the teachings of the patent, the Court must still go on to consider whether that gap can be filled in by the common general knowledge of the person skilled in the art. This makes insufficiency a nebulous ground of invalidity, in particular because it requires the judge to put on a mantle of a person skilled in the art at the relevant time (which can be decades ago), and figure out what the person skilled in the art knows and does not know. For the latter, lawyers will know that it is immensely difficult to prove a negative. Consequently, insufficiency, while often relied on, is usually not the focus of any invalidation/revocation proceedings.

On 17 February 2023, the Singapore Court of Appeal released its judgment in IIa Technologies Pte Ltd v Element Six Technologies Limited [2023] SGCA 5 (“IIa”). In that judgment, the Singapore Court of Appeal not only revoked the patent in issue on the ground of classical insufficiency, it also recognised for the first time in Singapore a new type of insufficiency called “insufficiency by uncertainty”. This insufficiency arises where the person skilled in the art is unable to determine whether a particular product or process is within or outside the scope of the claim. In other words, the patent is so unclear that it is impossible for a person skilled in the art to figure out what he has created.

“Insufficiency by uncertainty” is not to be confused with lack of clarity, although they are similar. They differ in the extent to which the lack of clarity can be said to have impugned the validity of the patent. The test for clarity is whether a person skilled in the art can understand the words used in the claim. For uncertainty, the lack of clarity must be so great that it leaves the person skilled in the art unclear as to how to determine whether a particular product or process is within the scope of the claim.

In IIa, the subject patent concerns an allegedly new method of growing a diamond via chemical vapour deposition (“CVD”). The CVD diamond in the main independent product claim of the patent was described using qualitative parameters, one of which was that the diamond had to have birefringence where δ falls within π/2. The product claim further required that the CVD diamond is measured only with an esoteric measurement equipment called the Metripol. Less than 20 such machines were sold globally. Knowledge of how to use the machine was therefore scant.

It was common ground between the parties that the Metripol, on its own, does not give the person skilled in the art data to determine whether δ falls within π/2. The question was whether there were any other available solutions at the relevant time to solve this problem. The answer was no. The Singapore Court of Appeal found that a person skilled in the art would not know how to determine whether a particular diamond satisfied “δ falling within π/2”. Neither the Metripol nor the common general knowledge could plug this gap. Consequently, the main independent product claim was uncertain and therefore invalid.

But uncertainty proved to be wieldier than just merely to invalidate one claim.

First, since all the rest of the dependent claims ultimately referred to claim 1, the uncertainty of claim 1 infected the rest of the claims in the subject patent, and the patent was revoked in full.

Second, it can also prove non-infringement. English patent law accepts that even though lack of clarity cannot result in a patent being invalid, it can result in the patentee being unable to establish infringement because “[i[f you cannot define the invention claimed, you cannot conclude that it is being used”. The Singapore Court of Appeal in IIa did not expressly affirm and adopt this line of reasoning. But, in finding that the patentee failed to prove infringement because the test results from the Metripol could not prove that any of the alleged infringing diamonds satisfied “δ falling within π/2″, it appears that the Singapore Court of Appeal implicitly accepted that lack of clarity can be relied upon as a defence against infringement. It remains to be seen whether this will be interpreted as such in subsequent patent cases in Singapore.

IIa marks one of the rare instances where an entire patent was invalidated for insufficiency in Singapore. It is a signal to all patentees who are applying or intend to apply for a patent grant in Singapore to revisit their patent specifications to ensure not only that the patent clearly teaches the invention clearly and completely , but that it also clearly defines the invention to enable a person skilled in the art to determine whether a product or process falls within the patent claims.

IIa is also a caution to patentees who wish to draft their patent claims by referring to parameters measured by obscure and/or rare equipment. The risk is that if the patent does not fully teach a person skilled in the art how to achieve the said measurements using the equipment referred to, then then the patent is likely to be uncertain and consequently insufficient.

That, however, is not to say that patent claims can never rely on new measurement techniques or equipment to quantify the parameters in the claim. There may be circumstances where a particular characteristic can only be quantified with a particular parameter, and measured only in a particular way. Patentees should not, as a default, be penalised simply because of this. That would be the antithesis of the patent regime, which is to encourage discovery of anything novel and inventive. However, if and when a patentee chooses to rely on such an esoteric measurement technique or atypical equipment that is not in the common general knowledge, then the patentee bears the burden of fully teaching the person skilled in the art how to carry out that measurement. Afterall, a patent is only as good as it is understood.

In short, if you want to protect your patent, you must make sure that your patent is “crystal-clear”, like a diamond.

The author acted for lla at the trial and at the appeal.