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G1/15 – the death knell for poisonous divisionals
13 February 2017 by Lloyd Hoarton

Executive summary:

The threat of poisonous divisional attacks at the European Patent Office has been creating uncertainty for some years.  The February 2017 reasoned decision of the EPO's Enlarged Board of Appeal in G1/15 offers welcome respite.  In summary, whilst this decision does not directly address the question of whether or not a divisional application can be cited against its parent (or vice versa), if we follow the reasoning in the decision, the concept of a "poisonous divisional" necessarily disappears. This decision will be a strong tool to dispose of poisonous divisional attacks.

Detailed analysis:

The decision

The decision relates first and foremost to the issue of "partial priorities", i.e. whether a single claim can comprise subject-matter with different effective dates. This would generally occur where the claim is broader than the disclosure of the priority document.

Previously, it was thought that if a claim is not directed to "clear alternatives" (e.g. A or B) then the whole claim would lose its priority entitlement if only one alternative was disclosed in the priority document. This commonly occurred when a claim included continuous numerical ranges or Markush formulae in chemistry. 

The crux of this decision is that a claim may be "conceptually" divided into two parts, i.e. that which has a valid claim to priority because the subject-matter is disclosed in the priority document, and that which does not. Thus, even if the claim is not directed to clear alternatives by use of the word "or" or similar, it may still have partial priority. For instance, where the claim is directed to a numerical range (1-10), and only part of this range is disclosed in the priority document (e.g. 1-4), the range may be conceptually divided into two parts (e.g. 1-4 and 5-10), where the first part of the range has valid priority but the second part does not.

Relevance of the decision to a poisonous divisional scenario

The decision stops short of then applying this reasoning to a so-called "poisonous divisional" scenario. The fundamental question of whether a divisional can be cited against its parent, or vice versa was not considered. However, following the logic of the decision it appears that this decision may bring an end to the poisonous divisional issue in some circumstances.

In the above scenario, if a divisional application were filed it would necessarily have the same disclosure as the parent (i.e. it would disclose the range 1-10). As the divisional takes the same filing date as the parent, and claims the same priority, the same logic should apply. In other words, the range disclosed in the divisional application may also be conceptually divided, as it was in the parent claims, so that part of the range is entitled to priority, and part of it is not. If this is the case then the subject-matter of the divisional will always have the same effective date as the same subject-matter in the parent application and neither can be prior art against the other.

However, this favourable interpretation depends on how you apply Article 54(3) EPC, which states that European patent applications having a filing or priority date prior to the effective date of the claimed subject-matter, and a publication date afterwards, are citable against the claim for novelty (not inventive step).  The question is whether or not a divisional application may be such an Art. 54(3) EPC application. Specifically, this comes down to whether you adopt a "whole contents" interpretation, or a "same subject-matter" interpretation of Article 54(3) EPC. 

The above favourable interpretation employs the "same subject-matter" interpretation, which complies with the Guidelines G,5.1.1:"If the published European patent application [claims priority, the priority date replaces the filing date for that subject-matter in the application which corresponds to the priority application".

Applying these Guidelines, the 54(3) application may also be divided into parts which validly claim priority and parts which don't. It follows logically that only those parts of the 54(3) document which validly claim priority can be citeable against a later application, and then those parts are only citable against subject-matter within the later application which has a later effective date. Since the subject-matter disclosed in a divisional will always have the same effective date as the same subject-matter in the parent it seems would seem impossible for a divisional to be cited against its parent.

Note that this does not preclude a "toxic priority" problem where a priority application has a narrower disclosure than the priority claiming application and is published before the filing date of the priority claiming application.

The "whole contents" interpretation, on the other hand, suggests that the whole of the disclosure of a 54(3) document is citeable against the claimed subject-matter if the claimed subject-matter is not entitled to priority,  regardless of whether or not the  specific subject-matter within the divisional application which is being cited against the claim is actually entitled to priority. This comes from a literal interpretation of The Guidelines G, 5.1, which states that "By the "content" of a European application [referring back to Art. 54(3) EPC"] it is meant the whole disclosure, i.e. the description, drawings and claims,…"

This "whole contents" approach seems inconsistent with this new decision which advocates  conceptually carving up a claim or application into parts which do, and parts which do not claim priority (see especially reasons point 5.1.2).

Thus, whilst this decision does not directly address the poisonous divisional problem, it goes some way to addressing it if we follow the overarching logic of the decision.