A referral has been made to the Enlarged Board of Appeal at the European Patent Office (EPO) for consideration of the issues underlying the concepts of "toxic priority" and "poisonous divisionals". The exact questions to be answered by the Enlarged Board have now been determined, and are reported here.

As reported in detail in an article that featured in our Spring / Summer 2015 edition of Inside IP (see page 29), the related concepts of “toxic priority” and “poisonous divisionals” have caused a great deal of recent debate.  The underlying issue concerns partial and multiple priority rights for a claimed invention, the application of which is unclear following divergent decisions by the Technical Boards of Appeal at the EPO.

In view of this divergence a referral has been made to the Enlarged Board, for the matter to be considered further.  We have been waiting for determination of the exact questions to be answered by the Enlarged Board.  This has now occurred, following publication of Technical Board of Appeal decision T 0557/13.  

T 0557/13 provides a comprehensive review of the current state of play and makes for an informative read for those interested in the detail (see 10-15, 17.2.3 and 18.1.3, Reasons for the Decision, in particular).  A fundamental issue to be resolved in this case was “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”.  The answer to this question impacts on the assessment of novelty for the patent under review, and particularly novelty over that disclosed in the patent’s own parent application (a potential case of “poisonous parent”, rather than “poisonous divisional”, therefore)!

T 0557/13 refers back to an earlier decision of the Enlarged Board, G 2/98, in which it was stated that a claim directed to a generic term, formula or otherwise that encompasses, but does not specifically define, each of the possible alternatives (a so-called generic “OR”-claim) is entitled to claim multiple priorities “provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters”.  Having reviewed the legal framework and case law (both pre- and post- G 2/98) concerning partial priority, the Technical Board recognised that, in order to resolve the issue in T 0557/13, clarification is required as to what the “limited number of clearly defined alternative subject-matters” referred to in G 2/98 actually means.

The Technical Board expressly appreciated the right of priority as one of the cornerstones of the patenting system, and recognised that clarification of the issues surrounding partial priority will be of great practical importance for both claim drafting and filing strategies.  It therefore purposely formulated the referral questions in terms broader than those suggested by the parties involved.  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?

Thus, referral questions 1-4 have been carefully framed in terms which reflect the fundamental importance of partial priority in a general sense.  The issue of partial priority can of course arise whenever there is state of the art potentially relevant under either Article 54(3) EPC (so-called “novelty only” citations) or 54(2) EPC, and not only in situations caught by the concepts of “toxic priority” and “poisonous divisionals”.  These questions also address whether the condition referred to in G 2/98 can even be applied to partial priority for generic “OR”-claims, as opposed to claims involving multiple priorities (the true subject of G 2/98).

Referral question 5 is closely linked, but goes to the heart of “poisonous divisionals”, asking whether Article 54(3) EPC can be applied to potentially colliding European parent and divisional applications.

As we had hoped, therefore, the referred questions look set to rationalise how partial and multiple priorities should be applied.  An opinion or decision from the Enlarged Board in this regard should remove legal uncertainty and thus clarify the validity of priority-claiming European patents and applications.  Knowing when partial and multiple priorities are available would enable a better understanding of whether priority documents can ever be toxic or divisional applications poisonous.

In the meantime, readers are referred back to our earlier article for the steps that applicants for European patents can take in order to protect themselves against the alleged threat of “toxic priority” and “poisonous divisionals”.  

Tanya Heare