In case G 1/15 the EBA has decided that partial priority claims are valid – a later broader claim cannot be anticipated by an earlier, narrower disclosure from which it claims priority.

An appeal to the EPO Enlarged Board of Appeal (EBA) has was made in order for the EBA to decide whether a first patent application that is published can be novelty destroying when cited against a further application that claims priority from the first application. In short, can a priority filing be ‘poisonous’ to the novelty of a later application? The EBA have supplied a short answer in Decision G 1/15: No it cannot.

The EBA have supplied a short answer in Decision G 1/15: No it cannot.

This appears to be a sensible conclusion and the decision provides a comprehensive analysis of the case law leading up to the decision, the legal framework supporting priority, the effects of priority and the purpose of the priority right.

Background: Why would a priority filing be “poisonous?”

Turning to why this case arose and how a patent application for an invention might be ‘poisoned’ by a priority application for the same invention.

First, we note that in producing an invention and inventor will normally create a specific embodiment of that invention that demonstrates the inventive concept in action. In then claiming an invention by way of the patent system, it is normal to submit a first application to a Patent Office disclosing this original embodiment of the invention in order that the inventor can stake their priority claim to the invention.

The inventor then has a window of opportunity of one year (the “priority year”) to further develop the invention. This development might include expanding the uses for the invention beyond the original embodiment, or might relate to components of the invention. For example, the earlier disclosure of the invention might only utilise, e.g. copper, whereas the broader, more developed, version of the invention might be disclosed as being for ‘metal’ in general. In this way the inventor is afforded an opportunity to fully explore and then claim the benefits of their inventive contribution to the state of the art.

Normally, such further developments are then claimed in a second patent application that claims the priority date of the first application. This second application may for example be an international application. The criteria for assessment of whether a priority claim is valid and should be accepted is whether the second application claims the “same invention” as the first application.

Necessarily the disclosures in the first and second applications overlap to a very considerable extent. In general, the second, normally more expansive, application is published and the first, more specific, application is allowed to lapse and so remains unpublished. In this way the earliest date of priority is available but only the later and broader disclosure is made available to the public.

However if the earlier application is allowed to proceed to publication the earlier application may be considered prior art in the second application.

Thus in the example above, the specific embodiment disclosed in the first application (for copper) falls within the scope of the broad claim of the second application (for metal). Accordingly, this may be considered to be novelty destroying for the second application. This effect on the second application has led such a first application to be termed a “poisonous priority”.

Decision G 2/98

An earlier Decision from the EPO Enlarged Board of Appeal considered the issue of whether a broader later application could claim priority to a narrower earlier application, questioning whether the applications were to the same invention. As a general indication the Board held that priority to the earlier application should be acknowledged only if the skilled person can derive the subject-matter of the claim of the later application “directly and unambiguously, using common general knowledge, from the previous application as a whole”.

More specifically the Board was asked to consider whether a claim can be considered to have multiple or partial priorities, in a situation as described above where a second application has an expanded claim compared to an earlier application from which is claims priority. The Board held that partial or multiple priority was acceptable provided that “it gives rise to the claiming of a limited number of clearly defined alternative subject-matters”.

In relation to the example described, this would seem to imply that a second application to copper or zinc or gold or silver would be acceptable as the claim in relation to copper could be accorded the earlier priority date while the claim in relation to zinc or gold or silver would attract the date of the second application. However, a second application to a metal would not be acceptable as this is a generalisation of copper and is not divisible into a limited number of clearly defined alternatives.

Decision of the EPO Enlarged Board of Appeal (EBA) for G 1/15

This is the situation that the EBA has been considering in case G 1/15.

Specifically the EBA was asked to consider the following question;

Where a claim of a European patent application or patent encompasses alternative subject-matters by virtue of one or more generic expressions or otherwise (generic “OR”-claim), may entitlement to partial priority be refused under the EPC for that claim in respect of alternative subject matter-disclosed (in an enabling manner) for the first time, directly or at least implicitly, an unambiguously, in the priority document?

The Board referred to the Paris Convention, which provides the foundation for the priority right, and noted that one of its primary purposes was to avoid “self collision” whereby an inventor’s disclosure of a technical advance in one jurisdiction would prevent that technical advance being patented and exploited in another jurisdiction. The Board concluded that priority is a right with the only substantive condition being that it is to “the same invention”. The Board also reviewed the travaux preparatoires to the EPC and recognized that both multiple priorities and partial priorities were specifically considered and intended to be encompassed by the EPC.

As a result the Board concluded that the EPC does not contain any other requirements for recognising the right of priority beyond that of the same invention. This applies to simple, multiple or partial priority, with partial priority being considered to be a sub-group of multiple priorities. Thus the proviso in G2/98 that the wording of the claims “gives rise to the claiming of a limited number of clearly defined alternative subject-matters” cannot be regarded as implying a further limitation of the right of priority.

In response to the question above the short answer from the EPO is “no”. An order was issued stating as follows:

Under the EPC, entitlement to partial priority may not be refused for a claim encompassing alternative subject-matter by virtue of one or more generic expressions or otherwise (generic “OR”-claim) provided that said alternative subject-matter has been disclosed for the first time, directly, or at least implicitly, unambiguously and in an enabling manner in the priority document. No other substantive conditions or limitations apply in this respect.

Thus a legal antidote has been asserted to cure poisonous priorities.

As several cases have been stayed pending the outcome of this Decision the effects of the Decision will quickly be felt and it is believed that this troublesome issue has now been fully and finally resolved.


Our articles are for general information only. They should not be considered specific legal advice, which is available upon request. All information in our articles is considered to be accurate at the date of publishing.

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