TL;DR: Thinking of using PPH in Singapore after filing a request for examination? Think again.

With the patent system in Singapore currently experiencing a significant backlog in examination, it is understandable that applicants want to obtain grant as quickly as possible. Singapore’s Patent Prosecution Highway can be an effective way to accelerate examination.

IPOS currently offers an apparently attractive procedure that, in our view, carries real legal risk. Applicants and advisers should consider that risk carefully before relying on it.

This post explains the issue in practical terms and suggests how to avoid the problem.

Why Applicants Use the Patent Prosecution Highway

The Patent Prosecution Highway (PPH) allows an applicant to request accelerated examination in Singapore based on claims that have already been allowed in a corresponding foreign application, typically at a major office such as the European Patent Office (EPO), Japanese Patent Office (JPO) or the United States Patent and Trademark Office (USPTO).

Once the Singapore claims are amended to correspond to the allowed or granted claims in the foreign application and PPH is requested, IPOS will fast track examination of the Singapore application. This can significantly shorten the time to grant.

There is an important constraint: the Singapore claims as presented for examination must match the allowed or granted foreign claims. If they do not, they must be amended to do so, before the PPH can begin.

The Timing Problem

Under Singapore patent law, voluntary amendments are generally not allowed once a request for examination has been filed. The only exception is if they are made in response to a Written Opinion.

This means that once you file a request for examination in Singapore, you are no longer free to amend the claims of your own volition. At the same time, the PPH requires that your Singapore claims already correspond to the foreign allowed or granted claims.

In practical terms, this means that the Singapore claims must be amended to correspond to the foreign claims at the latest by the time the request for examination is filed.

A Bit of History

When IPOS first adopted the PPH, the patent system in Singapore was widely regarded as one of the most efficient in the world. A first Written Opinion could often be expected within three to six months of requesting examination, and grant could follow quite quickly thereafter. In that environment, the additional procedural steps required for PPH were not always commercially compelling. Many applicants were content to proceed under the normal examination timelines.

The position today is starkly different. Examination timelines have lengthened significantly at IPOS and there is a big backlog of examination at that office. It is not uncommon for a first Written Opinion to issue up to two years after a request for examination is filed. In some cases, there may even be a prolonged administrative delay before the file is even sent to the examining division. Time to grant has slipped significantly.

Unsurprisingly, this has increased interest in the PPH as a means of accelerating patent prosecution in Singapore. The difficulty arises where an applicant filed a request for examination months or years ago, at a time when acceleration did not seem necessary. A granted or allowed corresponding foreign application may now be available, making PPH commercially attractive. However, under the Act and Rules, it is already too late to amend the Singapore claims in order to request PPH.

PPH After Requesting Examination

In an effort to address this, IPOS introduced an administrative process in October 2023. Under this process:

  1. You have an application for which you have already requested examination.
  2. If you later decide you want to seek PPH, you email IPOS to say so.
  3. If examination has not yet started, IPOS issues an Invitation to Amend.
  4. You amend your claims to match the foreign allowed claims and request PPH in response to the Invitation to Amend.

This process avoids having to withdraw and refile the examination request, and in some cases avoids paying extension fees. At first glance, this process looks efficient and attractive. The question is whether it is legally secure.

Why We Believe There Is Significant Risk

Restrictions on Voluntary Amendments After Requesting Examination

The availability, timing and restrictions on voluntary amendments are set out in the Patents Act and Rules. The Act and Rules generally do not allow voluntary amendments after a request for examination is filed. The only way you can do so after examination has been requested is by way of a response to a Written Opinion issued during examination.

Under the new IPOS “PPH after examination request” process, however, IPOS invites you to amend the claims after a request for examination has been filed, but before examination has started. That is precisely the period during which voluntary amendments are prohibited under the Act and Rules.

This is crucial because it raises a real question about whether those amendments have a firm legal basis. The fact that IPOS has invited an amendment does not, in our view, make valid what would otherwise be a prohibited voluntary amendment.

The Nature and Purpose of an Invitation to Amend

Invitations to Amend were introduced in 2022 to allow Examiners to deal quickly with minor defects identified during substantive examination. These include correcting claim dependencies and resolving minor formal issues.

This is not merely our view. IPOS has described the procedure in these terms in its communications, and the Second Minister for Law explained in Parliament that the change was intended to allow Examiners to invite minor amendments that would overcome objections, without issuing a full Written Opinion and requiring a formal response.

Invitations to Amend are therefore not intended as a general channel for applicants to make amendments for administrative convenience.

It is also less than clear that the law actually allows voluntary amendments to be filed in response to an Invitation to Amend. Rule 49(3)(b) and (c) read together with Rule 46(3)(b) of the Singapore Patents Rules expressly provide that the applicant may voluntarily amend the specification as part of a response to a Written Opinion. There is no corresponding provision in the part of the Rules dealing with Invitations to Amend (Rule 46AA).

The absence of any explicit statutory wording permitting voluntary amendments in response to an Invitation to Amend is highly significant, in our view. Yet, this is precisely what is happening within the IPOS “PPH After Requesting Examination” procedure.

Claim Alignment is a Voluntary Amendment

The Singapore Patent Act and Rules recognise two categories of amendment during examination:

  • amendments made in response to an objection raised by the Examiner, typically in response to a Written Opinion; and
  • voluntary amendments made at the applicant’s own initiative.

Where an applicant seeks to replace the claims originally offered for examination with a different set of claims corresponding to a foreign allowed or granted application, for example to pursue accelerated examination under the Patent Prosecution Highway, that change can only fall within the category of voluntary amendment. It is plainly not an amendment made in response to an objection raised by the Examiner.

It is therefore important to be clear about what the IPOS procedure seeks to achieve. In effect, it seeks to permit an applicant to substitute the set of claims submitted for examination with a potentially wholly different set of claims after a request for examination has already been filed.

In substance, this amounts to permitting voluntary amendments to the specification after the filing of the examination request, which is prohibited by the Act and Rules. Again, just because IPOS allows it does not mean that it is compliant with the Patents Act and Rules.

What Is the Real Risk?

The risk is not just procedural inconvenience, but rather to the validity of the eventual patent. This is because Singapore law allows a patent to be revoked if an amendment was made that “should not have been allowed” (Section 80(1)(e)).

If a third party later challenges the patent, it could argue that:

  • the amendment to the claims to match the foreign claims was voluntary and not permitted under the Act and Rules
  • the Invitation to Amend should not have been issued in those circumstances
  • it is not possible under the Act and Rules to file voluntary amendments in response to an Invitation to Amend
  • the amendment therefore “should not have been allowed”

Even if such a challenge is not guaranteed to succeed, the existence of a credible argument creates litigation exposure. That risk may complicate enforcement, affect licensing negotiations, reduce commercial certainty and increase due diligence risk in transactions.

For some portfolios, especially high value patents, that may be a material concern.

These concerns are not purely academic. The Association of Singapore Patent Attorneys (ASPA) has written to IPOS to raise the same issues and to seek clarification on the statutory basis for this procedure. We are awaiting IPOS’ response.

Until IPOS provides that clarification, applicants and advisers should avoid relying on the IPOS “PPH after requesting examination” route if they want to minimise risks to the validity of their patents.

Why This Matters for Commercial Decision Making

When patent applicants seek to accelerate the prosecution of their applications, the focus is often on speed. That is understandable. However, in our view, acceleration should not come at the cost of risking the validity of a patent. A patent granted quickly but carrying an avoidable procedural vulnerability may ultimately be less valuable than a patent granted slightly later but procedurally robust.

If there is any real doubt about whether an amendment was lawfully permitted, that doubt will surface during enforcement or revocation proceedings. Opponents routinely scrutinise file histories when considering litigation, and a visible procedural irregularity is an obvious target.

What Should Applicants Do Instead?

The safest approach is straightforward: if you intend to rely on the PPH, make that decision before filing your request for examination.

In practical terms:

  • review the foreign prosecution position early
  • decide whether you are likely to rely on foreign allowed claims
  • amend the Singapore claims before filing the examination request
  • request PPH at the same time you request examination

This avoids the need for any post examination request amendment and keeps you comfortably within the amendment provisions of the Pateents Act and Rules.

If examination has already been requested and PPH has not been sought, you need to carefully consider what to do. Withdrawing and refiling the examination request would be procedurally cleaner than relying on the IPOS “PPH after requesting examination” route, but might not be possible in some cases, or involve considerable expense. The correct strategy will depend on the importance of the application and the commercial context, and we would be pleased to provide further advice and guidance (including on other ways of potentially accelerating examination at IPOS).

Our View

The policy objective behind the current IPOS practice is understandable. Reducing backlog and improving turnaround times benefits the system. However, where a procedural shortcut raises doubt about the statutory basis for amendments, applicants should proceed with caution. Speed is valuable, but legal certainty matters more when the patent may need to withstand challenge.

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