APAA e-Newsletter (Issue No. 38, December 2023)

Plausible Patentability: A Tale of Legal Lore From Europe to the Lion City

Gerald Koh - Viering Jentschura & Partner LLP (Singapore)


The requirement for plausibility has become an important consideration in patent applications in many jurisdictions outside of Singapore. This article examines the origins and rationale behind plausibility, its relevance to the Singapore context, and whether the introduction of such a requirement would be justified.

Origins in Foreign Jurisdictions

The plausibility requirement originated in Europe, particularly from case law of the European Patent Office’s Boards of Appeal. A key decision was the Factor-9/Johns Hopkins case, which stated that “The definition of an invention as being a contribution to the art, i.e. as solving a technical problem and not merely putting forward one, requires that it is at least made plausible by the disclosure in the application that its teaching solves indeed the problem it purports to solve.”[1]

Recently, the EPO Enlarged Board of Appeal in G 2/21 provided further guidance on plausibility, clarifying the role of post-published data in evaluating inventive step. While confirming such data cannot be disregarded solely for being post-published, the decision emphasized assessment should focus on “what the skilled person, with the common general knowledge in mind, understands at the filing date from the application as originally filed as the technical teaching of the claimed invention.”[2]

The rationale given for plausibility is that it helps distinguish truly inventive contributions from speculative or implausible assertions in patent applications. The EPO and other jurisdictions do not want to grant patents for speculative, unsupported possibilities that the applicant hopes may work, but has not demonstrated have any technical effect. Requiring plausibility aims to ensure patent rights are only granted for inventions that have been shown or soundly explained to have a technical effect and solution to a technical problem.

Applicability in the Singapore Context

Singapore’s Patents Act does not explicitly refer to a requirement for plausibility. The key provisions governing patentability refer to novelty, inventive step, industrial applicability, and sufficiency of disclosure.[3] There are presently no local court decisions that read in an additional requirement for plausibility not found in the Act.

It could be argued plausibility is inherent within the existing grounds of industrial applicability and sufficiency of disclosure. However, courts are usually reluctant to read in requirements not explicit in legislation. Industrial applicability requires the invention to be capable of industrial application. An implausible invention may indeed be capable of industrial application theoretically, albeit speculatively. Sufficiency of disclosure relates more to the adequacy of the description to enable performance of the invention.[4] A far-fetched or speculative invention can still be sufficiently described to allow reproduction by a skilled person, even if its effects may not be convincing.

Overall, Singapore’s current statute-based framework does not readily imply a need for plausibility without substantive addition to existing patentability criteria. Its introduction would likely require legislative amendment or at minimum, judicial activism in interpreting existing provisions.

Assessment of Justifications for Introduction

Notwithstanding the lack of clear legal basis, might there be compelling policy reasons to introduce plausibility as a patentability requirement in Singapore?

A key justification is improving patent quality by setting a higher threshold for demonstrations of technical effect at the application stage. This could discourage speculative patent applications and inefficient monopolies being granted. However, Singapore’s system already prevents undue speculative applications through stringent standards of disclosure and specificity. The bar for establishing industrial applicability and inventiveness is already comparable to other jurisdictions. Introducing plausibility risks adding complexity without significant incremental benefit.

Another argument is that it reduces the need for post-grant revocation actions by tackling deficiencies earlier during examination. However, Singapore already has efficient and cost-effective mechanisms for pre-grant submission of third party observations. Plausibility objections are also likely to lead to drawn out disputes similar to inventiveness, without adding much substantive benefit.

Potential negatives of introducing plausibility are that it adds uncertainty, reduces disclosure incentives, and disadvantages individual inventors and startups over corporations with greater resources to demonstrate plausibility upfront. It may be an excessive barrier in fields like pharma and biotech where efficacy testing is expensive and disclosure necessarily more theoretical at the application stage.


On balance, Singapore’s existing patentability standards seem adequately robust. While the goals of plausibility are laudable, current law already empowers examiners to reject speculative applications lacking substance and industrial applicability. A better solution may be more stringent examination guidelines and training for examiners for identifying dubious assertions of technical effects or solutions. Sharpening application of present law is preferable to introducing an additional stand alone ‘plausibility’ requirement which risks muddying the waters.



[1] T 1329/04 (Factor-9/JOHNS HOPKINS)

[2] G 0002/21

[3] Sections 13-16, Patents Act (Cap. 221)

[4] Sections 25(4) and 80(1)(c), Patents Act