UK: G1/15: Partial Priority For A Generic Claim Less Limited By Clearly Defined Alternatives

Last Updated: 18 April 2017
Article by Chris Cottingham, Susan Keston and Mark Lunt

On 1st February 2017, the Enlarged Board of Appeal of the European Patent Office issued its long-awaited decision in case G1/15 clarifying that entitlement to partial priority is not to be refused where a claim encompasses alternative subject-matters, each having their own effective date, using one or more generic expressions.

The Enlarged Board of Appeal were responding to a referral in case T 0557/13 from the Technical Boards of Appeal which asked the 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, and unambiguously, in the priority document?"

The Enlarged Board of Appeal answered the question in the negative, holding that partial priority may not be refused in such situations. In particular, a claim including a generic expression which covers subject-matters, only some of which is disclosed in a priority document, may enjoy partial priority in respect of the subject-matters disclosed in the priority document provided that it is disclosed directly, or at least implicitly, and unambiguously and in an enabling manner in the priority document.

A similar situation had previously been decided by the Enlarged Board of Appeal in case G2/98 which held that "The use of a generic term or formula in a claim for which multiple priorities are claimed... provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters" (Reasons 6.7). Some of the case law from the Boards of Appeal following G2/98 interpreted the phrase "a limited number of clearly defined alternative subject-matters" in a strict way, with the effect that some Boards of Appeal only recognised partial priority for a claim including "or", or similar, between explicitly recited alternative subject-matters in the claim, which seemed to place more emphasis on claim form than the substance of the invention.

However, the Enlarged Board of Appeal in the present case states that the claim can be "de facto conceptually divided into two parts, the first corresponding to the invention disclosed directly and unambiguously in the priority document, the second being the remaining part of the subsequent generic "OR"-claim not enjoying this priority". This is a broad interpretation of the language used in case G2/98 and implies that a generic term necessarily encompasses the limited number of clearly defined alternative subject-matters required in case G2/98. This is good for Patentees because it makes it less likely that a generic claim will be refused partial priority overall due to the form of the claim, safeguarding priority entitlement to what is clearly and unambiguously disclosed in the priority document(s). In fact, the decision of the Enlarged Board should entirely remove the limitation "provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters" and is a welcome return to a common sense approach. It is to be noted with some regret that a number of patents have been lost to their proprietors on the back of this (now defunct) limitation.

Partial priority is a situation that arises commonly when a first application for a patent discloses a specific subject matter. Subsequently, a second application is filed claiming priority from the first application. The second application discloses the subject matter of the first application, in addition to a generic term for the specific subject matter. The second application includes a claim to the generic subject matter which would encompass the specific subject matter.

A simple example is where a first European application, EP1, discloses a feature formed from oak, whereas a subsequent second European application, EP2, claiming priority from the first application, and filed prior to publication of the first application, discloses the feature formed from oak as well as disclosing and claiming the same feature formed from wood. "Wood" is a generic term which includes oak, but would also cover other woods such as pine and ash.

The disclosure of oak for the first time in EP1 is within the scope of the claim to the feature formed from wood in EP2. EP1 is also citable as prior art for the purposes of novelty only against any of the claims of EP2 not entitled to the priority date of EP1. It seems that the European Patent Office will now recognise that the only subject-matter of the claim of EP2 not entitled to priority from EP1 is also the very subject-matter of the claim of EP2 not disclosed in EP1, and so the claim in EP2 would be valid over the disclosure of EP1. Previously, the situation has been held to be the opposite by some Boards of Appeal because it would find that claims including a generic expression not found in the priority document could not enjoy partial priority. In such a case, the claim of EP2 would have been invalid due to the prior filing of EP1 which falls within the scope of the claim of EP2. This situation was previously termed "poisonous priority". Now, there should be no case of self-collision between applications that have a common priority claim, even if not entirely valid claims.

The decision in G1/15 is important because it should remove the risks to applicants from filing "top-up" applications in the priority year, including details of further developments related to their inventions disclosed in the priority application. Commonly, such top-up disclosure would include generic expressions for some specific subject matter disclosed using specific terms in the priority application. Previously, applicants following such a strategy may have been advised, due to uncertainty in interpretation of partial priority following G2/98, that priority applications were withdrawn prior to publication to reduce any risk of a poisonous priority situation.

This decision also provides an antidote to the analogous case of poisonous divisionals. In a poisonous divisional situation, a divisional application discloses specific subject matter entitled to priority. The parent application includes a claim using a generic expression found not entitled to priority, but covering the specific subject-matter disclosed in the divisional application. As a result, under some previous interpretations by the Boards of Appeal, the divisional application was considered novelty destroying prior art against the parent application.

The full text of the decision can be found here.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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