Partial Priority - questions for the Enlarged Board now revealed

Thanks to the comments posted by keen-eyed readers here and here, it has come to this Kat’s attention that EPO Board of Appeal decision T 0557/13 has finally been published (despite the patent in question having already expired...). Tufty the Cat covered this appeal in an article in January, as he pawed through the minutes of the Board of Appeal hearing, and has since already published an in-depth analysis of the recently published decision here. This Kat will therefore give but a brief overview of the situation.

But first, some background.

Even Merpel is subject to partial priority

This decision relates to patent number EP 0 921 183 (which is the result of a divisional application) in the name of Infineum. The patent is directed towards the use of cold flow improvers in fuel oil compositions - essentially, introducing additives to diesel such that the freezing point of the diesel is lowered, thereby avoiding undesired characteristics in cold temperatures.

The appeal itself derives from a decision by the opposition division to revoke the patent, based on the fact that the claims were not fully entitled to their priority - the granted independent claim was a generalisation of a more specific disclosure in the priority document. As a result, the published parent application constituted prior art under Article 54(3), and was novelty-destroying.

Enlarged Board decision G 2/98 was cited by the opposition division. The independent claim of the patent features a generic chemical formula which, due to the variable nature of the described substituents, encompasses a number of alternatives but does not specifically define each alternative. This can be viewed as a 'generic "OR"-claim', in the language of G 2/98. With respect to this type of claim, Reason 6.7 of G 2/98 states:

The use of a generic term or formula in a claim for which multiple priorities are claimed [...] is perfectly acceptable under Articles 87(1) and 88(3) EPC, provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters.

The opposition division did not believe that the claim gave rise to the claiming of a limited number of clearly defined alternative subject-matters, and so revoked the claim.

Appeal

In the present decision, the Board of Appeal recognised that first and foremost, the issue to be resolved was whether partial priority could be claimed:

The concrete question to be resolved here is whether Claim 1 enjoys partial priority to the extent that the use of [a specific compound] as disclosed in [the priority document] is encompassed by the more generic definition of Claim 1, rather than being spelt out in it.

It therefore follows that there needs to be clarification as to what the "limited number of clearly defined alternative subject-matters" of G 2/98 means.

The questions referred are as follows:

1. 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?

2. If the answer is yes, subject to certain conditions, is the proviso "provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters" in point 6.7 of G 2/98 to be taken as the legal test for assessing entitlement to partial priority for a generic "OR"claim?

3. If the answer to question 2 is yes, how are the criteria "limited number" and "clearly defined alternative subject-matters" to be interpreted and applied?

4. If the answer to question 2 is no, how is entitlement to partial priority to be assessed for a generic "OR"-claim?

5. If an affirmative answer is given to question 1, may subject-matter disclosed in a parent or divisional application of a European patent application be cited as state of the art under Article 54(3) EPC against subject-matter disclosed in the priority document and encompassed as an alternative in a generic "OR"-claim of the said European patent application or of the patent granted thereon?

This Kat is pleased to see that the Board purposely formulated the questions in terms broader than those suggested by the parties, such that they reflect the issues of partial priority generally, which can arise whenever there is state of the art potentially relevant under either Article 54(3) or 54(2) EPC, and not only in situations of "poisonous priority".

This Kat would like to thank his colleague Rob Barker for authorial assistance with this post.