It is quite common, and sometimes crucial, for applicants to amend the claims in their patent applications during examination in Singapore. However, in Singapore amendments carry particular risks that can catch out even experienced practitioners.

Two issues arise repeatedly in practice. The first is added subject matter, where an amendment introduces a something that was not clearly disclosed in the application as filed. The second is unsearched subject matter, where the amended claims define an inventive concept that falls outside the scope of the search relied upon for examination. Either problem could derail prosecution, and in some cases can place a granted patent at risk.

Understanding these potential issues at an early stage is critical for applicants and their advisers.

If you are unfamiliar with the wider Singapore prosecution framework, you may find it helpful to first review our overview of the Singapore patent system here:
Singapore patent prosecution overview

Choosing the Right Examination Route

Every Singapore patent application must be both searched and examined before it may be granted. The request for examination must be filed by 36 months from the earliest priority date (or the filing date, where no priority has been claimed).

There are two primary routes for patent examination in Singapore. The main difference between the two routes is the source of the search report on which the Singapore patent examiner conducts his or her examination.

The first route is combined search and examination, where IPOS conducts both the patent search and the substantive examination of the patent application. This is the more robust route because the claims examined will always correspond directly to the claims searched. It is particularly suitable where amendments are likely or where the scope of the invention may evolve during prosecution.

The second route is to request examination relying on an existing search report. The existing search report could be the search report of a foreign corresponding application, or more commonly the International Search Report if the Singapore application is the Singapore national phase of an International Patent Application (PCT). This route can reduce cost and avoid duplication of work, but it should be used only where the subject matter of the claims intended to be pursued in Singapore is clearly covered by the existing search report.

Added Subject Matter

An amendment is only allowable in Singapore if the amended subject matter is directly and unambiguously derivable from the application as filed.

The test for added subject matter in Singapore is not whether the skilled person could arrive at the amended feature, but whether the application actually discloses it. Such a disclosure may be set out explicitly in the specification, or implied by it, but the specification must clearly and unambiguously disclose the subject matter of the amendment in question. Ideally, we should be able to point to some literal disclosure of the exact words or phrases we wish to use in the amendment, although this is not strictly necessary.

In Singapore, the standard for assessing added subject matter is reasonably strict, and is closely aligned with that applied by the United Kingdom Intellectual Property Office and the European Patent Office. The standard tends to be stricter than that applied under other jurisdictions such as the United States of America, where there is greater freedom to reshape claims after filing.

Risks of Intermediate Generalisation

During prosecution, it may be necessary to amend the claims to a narrower feature if a claim with a broad feature is not considered to be novel or inventive. However, if that narrower feature is not disclosed in the application, the amendment will introduce added subject matter and will not be allowed.

In the worst case scenario, a specification as filed might only use a broad term and disclose just a single example. If it turns out during prosecution that the claim using the broad term is not new or inventive, the applicant will need to narrow the claim to restore patentability. However, if the specification as filed does not disclose any features that may be used in an amendment to an acceptable narrower version, the only safe amendment is to limit the claim to the exact narrow feature in the example. That can leave the applicant with a claim that is technically valid but which may have very little commercial value.

As an example, a claim as filed might include the feature a “flexible element”, with the description only disclosing a specific example using a “rubber member”. In this case, it may not be possible during examination to amend the claim to recite an intermediate feature of an “elastomeric element”, for example, unless this is specifically disclosed in the specification as filed. Even though rubber is an elastomer (and a person skilled in the art would understand that to be so), that specific broader class has not been disclosed in the specification, and such an amendment would be considered as having added subject matter under Singapore practice.

Consequences of Added Subject Matter

The consequences of added subject matter being introduced during examination are potentially serious.

Under Singapore patent law, a patent may be revoked by application of a third party. One of the grounds for revocation is that the application has been amended so that it includes added subject matter. As Singapore patent law requires that any amendment to a granted patent not to broaden the protection afforded by the patent, it might not be possible to amend the patent post-grant to remove an undisclosed added feature, if doing so would broaden the patent. At the same time, the presence of the added feature makes it vulnerable to revocation on added subject matter. The patentee may then be caught in a trap or squeeze.

For these reasons, it is important for applicants and their advisors to be aware of the rules regarding added subject matter in Singapore, and to take care not to introduce by amendment any such added subject matter.

Unsearched Subject Matter in Practice

In Singapore, the Examiner is only required to examine subject matter that has been searched. If an amended claim defines an inventive concept that was not previously searched, the Examiner is not obliged to examine the claim (Section 29(7) and Rule 46(1)(e)). The only recourse at this stage is to file a divisional examination to restart the application process. Not only is this troublesome, it may be expensive and delay grant of a patent.

The issue of unsearched subject matter arises more often than many applicants expect.

One common example arises from an objection of lack of unity of invention during the International Stage. In such a case, if the International Searching Authority (ISA) searched only a first invention and left further inventions unsearched, any later attempt to amend the claims to one of those unsearched inventions may result in unsearched subject matter.

Unsearched subject matter can also arise where a feature that defined the inventive concept at the time of search is removed during amendment. In such a case, the Examiner may raise an objection that the “claims […]result in an inventive concept that was not reasonably apparent at the time of the initial search”. Here, although the original claims were searched, the amendment results in a new inventive concept which the Examiner regards as not having been searched. This issue is particularly relevant in the biotechnology and life sciences areas.

A further trap arises where the United States Patent and Trade Mark Office (USPTO) acts as International Searching Authority (ISA). Under USPTO practice as ISA, any multiple dependent claims that depend from other multiple dependent claims are not searched (PCT Rule 6.4(a), MPEP § 1843.03). When such claims are later pursued in the Singapore national phase, the Examiner may object that the scope of the claims contains subject matter that falls out of the scope of the search report. This is despite the fact that under Singapore patent law and practice, it is perfectly acceptable to pursue multiple dependent claims that depend on other claims which are themselves multiply dependent.

The situations set out above fall into two broad categories. In “whole-claim cases”, the invention now being pursued was never searched at all and a new search is usually required, often via a divisional. In “part-of-claim” cases, the invention was searched but the applicant amended the claims and by doing so changed the inventive concept. Such cases may sometimes be resolved by reverting the amendments so that the search report covers the subject matter of the claims.

Practical Guidance for Foreign Applicants

The most effective way to avoid both added and unsearched subject matter problems is to draft with structured fallback positions. The specification of the patent application should be drafted to disclose cascading levels of generality so that meaningful intermediate positions are available if the main claim fails. Dependent claims should be drafted to contain distinctive technical features that may be relied on for novelty or inventive step during examination. Doing so takes care and effort (and some thinking), but this effort will be rewarded if these dependent claims are able to provide useful fallback positions during examination.

When choosing the examination route, you should only request examination relying on an existing search report only where the subject matter of the claims as presented for examination falls clearly within the scope of the search report relied on. If a lack of unity of invention objection has been raised, or if substantial amendments have been made or are likely during prosecution, then the alternative of requesting combined search and examination is usually safer.

During prosecution, when seeking to amend the claims, applicants and their advisers should ensure that each amendment is clearly disclosed in the specification as filed. If the Examiner raises an objection citing unsearched subject matter, the applicant will need to make a strategic decision as to whether to revert the amendment or to file a divisional to obtain a new search for the claimed invention.

Final Thoughts

Singapore’s approach to added subject matter and unsearched subject matter reflects its emphasis on legal certainty and examination grounded in properly searched prior art. The standards applied will feel familiar to practitioners with UK and European experience, but may be a surprise to those more accustomed to US-style amendment practice. With careful drafting, thoughtful examination strategy and disciplined amendment practice, the risks can be managed and strong, enforceable patent protection can be secured.

Please feel free to get in touch if you would like to discuss Singapore prosecution strategy for a specific case.

Contact Cantab IP

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