The Danger of Self-Colliding Divisional Applications in the EPO

Last week I had the honor of speaking at the 27th Annual Pharmaceutical/Chemical Patent Practice Update put on by the New Jersey Intellectual Property Law Association’s Chemical Practice Committee. The entire program was fantastic, but one presentation that got a lot of attention was by Matthew Fletcher, a partner at Abel & Imray in London, on the danger of “self-colliding” divisional applications in the EPO. He was kind enough to let me share his article on this issue from Abel & Imray’s October 2013 Biosciences & Pharma Group Newsletter.

Self-Colliding Divisional Applications in the EPO

A divisional application and its parent can self-collide, as novelty-destroying prior art documents that are citable against each other under Article 54(3) EPC. Whilst that theoretical possibility has been disturbing patent attorneys’ sleep for some time, there is now confirmation in Technical Board of Appeal decision T 1496/11 that nightmares can become reality.

Where a European patent application includes claims that are not entitled to the earliest priority date but includes other subject matter, such as a specific example that is entitled to an earlier priority date than the claims, self-collision will be an issue if a divisional application is filed. Once validly filed, a divisional application is treated as an entirely separate European patent application from its parent and so has the same potential to be part of the state of the art under Article 54(3) EPC as any other European patent application.

The Priority Date(s) of the Claims 

Enlarged Board of Appeal Decision G 2/98 confirmed that a single claim may be entitled to multiple priority dates if the claim concerns a limited number of clearly defined alternatives. However, where subject-matter disclosed in a priority document cannot be isolated as a clearly defined alternative from within the scope of a broad claim, the broad claim may not be divided into a part that is entitled to the priority date and a part that is not. Therefore, claiming priority from an application describing a specific embodiment that falls within a broader claim, the subject matter of which broader claim is first clearly and unambiguously derived from a filing made later than the priority application, is unlikely to entitle any part of the broader claim to the priority date.

A Self-Colliding Divisional Application

A European patent or application that includes a specific embodiment that is present in a priority filing, but whose claim scope is only entitled to the filing date of the patent or application, would of course be valid in the absence of any relevant prior art dating from before the filing date. However, the filing of a divisional application can create such novelty-destroying prior-art. Once validly filed, a divisional application is an entirely separate patent application, the priority entitlement of which is assessed independently from that of the parent. Under the whole contents approach, a specific example in the divisional filing, entitled to a priority date that is earlier than that of the claims of the parent application, would form part of the prior art under Article 54(3) EPC. Thus, the presence of that example in the divisional filing could deprive the claims of the parent application of novelty (and, potentially, vice versa).

In the much-discussed Technical Board of Appeal case T 680/08, the earlier European application disclosed a range of total drive specific energy (SEC) of from 0.325 to 0.415 kWh/kg. A subsequent European application was filed with claims to a revised SEC range of from 0.330 to 0.415 kWh/kg. As the specific end point of 0.330 kWh/kg was not disclosed in earlier application, the new range in the claims of the subsequent European application was held to be not entitled to priority. Furthermore, the new range could not be divided into a clearly defined subject matter that is entitled to priority and another clearly defined subject matter not entitled to priority. Thus, the claim of the later European application as a whole was only entitled to the filing date. On publication the earlier European application became part of the state of the art under Article 54(3) EPC and the SEC range of from 0.325 to 0.415 kWh/kg disclosed in that document deprived the claim of the later European application of novelty.

Enlarged Board Decision T 1496/11 

The case decided in T 1496/11 related to an application directed to a method of verifying a security document. The first application disclosed a self-verification means comprising an optical lens in combination with a security device that comprised a printed or embossed feature. A later filed European application which claimed priority from that first filing omitted the printed or embossed feature in the claims. Using the strict disclosure test, that claim was found to relate to different subject matter from the first filing, being an intermediate generalisation not directly and ambiguously derivable from the first filing. Thus, the claims of the later European application as a whole were not entitled to the priority date.

A divisional application was filed that included an embodiment that was identical to one present in the first filing, and which had the printed or embossed feature. That embodiment is entitled to the priority and so, on publication of the divisional application, that embodiment constitutes part of the state of the art citable under Article 54(3) EPC against the novelty of the claims of the parent application. The fact that that same embodiment was also disclosed in the parent application is immaterial the validity of the claims, as the claims could not be separated into subject matter including the embodiment that is entitled to priority, and a further clearly defined alternative subject matter  not entitled to priority. Therefore, the disclosure of the embodiment in the divisional that fell within the scope of the claims of the parent, deprived the claims of the parent of novelty and the patent was revoked.

It remains to be seen whether other Boards will follow the logic applied in T 1496/11, or whether a way round this harsh result will be found. A possible alternative is allowing a claim to be entitled to multiple priority dates even where clearly defined alternatives are not directly identifiable in the claim, as suggested in T 1222/11. However, the so-called “poisonous divisional” result does appear to be consistent with the EPO’s adoption of a strict disclosure test when it assesses entitlement to priority. For example, it already appears to be the case that a European patent can lack novelty over an earlier European patent application from which it claims priority (see T 680/08).

Mitigation Against Self-Collision

The only way of fully mitigating against the self-collision of members of the same patent family is to ensure that all parts of a European application are entitled to the earliest priority date, i.e. by making no changes to the first filing during the Paris Convention year. Of course, in practice that is not always possible. When changes are made, the possibility for self-collision is lessened where the subject matter from earlier filings is included in the final application in such a way that enables the claim to be rewritten as a list of clearly defined alternatives, each of which can be assigned their respective priority date.

Therefore, careful assessment of the priority situation would be prudent before filing any divisional applications, including consideration of whether it is possible to take action to mitigate against self-collision.