The EPO Board of Appeal decision T0557/13 has been published and with it, the questions being referred to the Enlarged Board of Appeal for guidance on the issue of partial priority of a claim.

In G2/98, the Enlarged Board of Appeal held that a claim reciting a generic term or formula may be entitled to multiple priority dates if it gives rise to the claiming of “a limited number of clearly defined alternative subject matters”.  This opinion has generally served as a legal test for assessing whether a claim is entitled to more than one priority date.

However, in recent years, the Board of Appeal decisions have reflected a diverging approach in interpreting the phrase “a limited number of clearly defined alternative subject matters”.

In T1877/08 and T0476/09, a strict interpretation of the test of G2/98 was adopted. However, in the more recent T1222/11 and T571/10 decisions, a more liberal interpretation was adopted, allowing for the conceptual division of the claim into the required “limited number of clearly defined alternative subject matters”.

T0557/13 was an appeal against a decision of the Opposition Division, which found that the claims of the patent did not validly claim priority from the priority application.  As a result, the claims were deemed to have an effective date of the filing date of the application.

The issue of “poisonous priority” (or in this case, “poisonous parent”) arose however because the patent in question was a granted divisional application.  Since the parent application was entitled to the priority date, the parent application constituted prior art to the claims of the divisional patent for novelty purposes only under Art 54(3) EPC, similar to the Australia “whole of contents” concept.  Given that the parent and divisional applications disclosed identical subject matter, the claims of the divisional patent were found to lack novelty over the parent application.

On appeal, the patentee argued that a parent application and a related divisional application could not have different effective dates.

Following oral proceedings, the Board of Appeal decided that clarification as to the meaning of “a limited number of clearly defined alternative subject matters” is required and has referred the following questions to the Enlarged Board of Appeal for consideration:

  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?

The Enlarged Board now has an opportunity to eliminate the chance of self-collision of patents/patent applications once and for all.  Whether or not they will avail of the opportunity to do so remains to be seen.  However, it is at least expected that some clarity will be provided as to how “a limited number of clearly defined alternative subject matters” should be interpreted.  Unfortunately, it is likely to be at least a year before the Enlarged Board provides some answers.

In Australia, section 43(3) of the Patent Act 1990 provides for a claim to have multiple priority dates in the case where it defines more than one form of an invention.  However, similar to the situation in Europe, the Australian courts seem to have taken a mixed approach in interpreting this provision.

In AstraZeneca AB v Apotex Pty Ltd [2014] FCAFC 99, a strict interpretation was adopted by the Full Federal Court and it was held that not every possible variation of the claimed invention can be treated as a different form of the invention entitled to its own priority date.  However, more recently in Nichia Corporation v Arrow Electronics Australia Pty Ltd [2015] FCA 699, the claims were recast in a format that recognised different forms of the invention, each being entitled to its own priority date.  For the moment, it seems that the possibility of self-collision of patents/patent applications in Australia will need to be assessed on a case-by-case basis.

In contrast, in New Zealand, section 62 of the Patent Act 2013 allows a claim to have only one priority date, that being the date on which the claimed subject matter is first disclosed in combination.  As a result, there does not seem to be an easy fix to the problem of “poisonous priority”.  Accordingly, self-collision of New Zealand patents/patent applications is a real possibility.

In general, the trap of self-collision is set when a patent application includes claims directed towards a broader or more generalised version of the invention disclosed in the priority application.  Regardless of whether or not the invention was simply described too narrowly in the priority application or indeed, as the case may be, it only became clear during the priority period that the invention may be claimed in a broader form, serious consideration needs to be taken when crafting the more generalised form of the claim to afford the best chance of the claim being deemed entitled to partial priority.  In particular, to the extent possible, the claim should clearly define the narrow form of the invention and the more generalised version of the invention as clear and distinct alternatives.  Otherwise, if the priority application is published or a divisional application is filed and published, the application or its divisional may fall foul of the trap of self-collision.