IP Cases & Articles

Poisonous divisionals (G1/15)

In our April 2015 edition of this newsletter we discussed the concept of multiple priorities and how, based on a strict interpretation of comments made in decision G2/98 concerning priority, the situation has arisen whereby a patent can be found invalid with respect to the disclosure of its own priority document, or its own parent/divisional application.

The Technical Board of Appeal in case T 557/13 had indicated that questions were to be referred to the Enlarged Board of Appeal on this matter, and their written interlocutory decision has recently been published setting out the questions to be referred to the Enlarged Board, along with a detailed discussion of the background to partial priority [see note 1 below].

As promised, this article provides a more detailed discussion of the case from which the referral emanates.

First instance

The patent at issue was revoked by the Opposition Division (OD). In particular, the OD found that the patent – a divisional application – lacked novelty under Article 54(3) EPC in view of the disclosure of its published parent application.

Claim 1 related to the use of an oil-soluble polar nitrogen compound, defined by a generic formula and present within specified limits, as an additive to enhance the lubricity of a fuel composition having a specified sulphur content.

Example 1 of the patent disclosed a specific polar nitrogen additive falling within the scope of claim 1 for the use defined in claim 1. The same example is disclosed in the parent application which was filed on 08 June 1995.

The parent application claims the priority of a GB national application filed on 09 June 1994 (the priority document). The priority document discloses the use of polar nitrogen compounds, but crucially not as generally as in claim 1 of the patent. Furthermore, the priority document contains the same example 1 as in the parent application and the patent [see note 2 below].

Accordingly, the OD found that the subject matter of claim 1, resulting from the generalisation of the more specific disclosure of the priority document, does not represent the 'same invention' as set out in the priority document. Therefore, the subject matter of claim 1 is not entitled to the priority claim, thus is effective as of the filing date. In contrast, example 1 of the parent application is the same as that disclosed in the priority document and thus this disclosure is entitled to the priority date.

Consequently, the OD concluded claim 1 lacks novelty over the disclosure of example 1 in the parent application under Article 54(3) EPC.

Second instance

Following the decision of the OD, the patentee filed an appeal alleging that the OD erred in its finding that claim 1 lacks novelty over the parent application.

In particular, the patentee argued that anticipation of a divisional application by its parent (so called 'self-collision') should not be possible because:

  • A broad interpretation of the test set out in reason 6.7 of G2/98 – "provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters" – is the correct approach to partial priority, so priority had to be acknowledged for the subject matter of claim 1 to the extent that it encompassed the subject matter disclosed in the priority document, ie, example 1. Accordingly, the parent application, although disclosing the same subject matter, did not have an earlier date and therefore is not prior art.
  • Article 54(3) EPC provides a statutory bar to self-collision as European patent applications which are the subject of this provision cannot include all European patent applications, or else the ludicrous situation could arise of a patent colliding with itself. Accordingly, Article 54(3) EPC cannot be directed to applications in the same family, and as such a parent application cannot be prior art for its own divisional application and vice versa.

The opponent rebutted each of the above points. In particular:

  • by advancing a stricter interpretation of "a limited number of clearly defined alternative subject-matters" based on that adopted by the Technical Boards of Appeal in earlier decisions; and
  • by arguing that the wording of Article 54(3) EPC precluded collision of a European application with itself but not of separate applications such as a divisional with its own parent.

In the reasons for the decision the Technical Board of Appeal gave careful consideration to the proper approach that should be adopted for assessing whether the subject-matter of claim 1 of the patent can be awarded a partial priority to the extent that the use of the additive of example 1 is encompassed by claim 1, rather than being spelt out in it.

Questions to the Enlarged Board of Appeal

The Technical Board of Appeal concluded that there is a divergent approach in the case law to the assessment of when to award partial priority. Furthermore, as this matter relates to a point of law of fundamental importance, it was found necessary to refer the following questions to the Enlarged Board of Appeal:

  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 G2/98 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?

Questions 1 to 4 see k to obtain clarity on the matter of partial priority, regardless of whether the potentially conflicting prior art is a priority document, divisional application or an unrelated application.

Question 1 essentially asks if, as a matter of principle, is it possible to deny partial priority for a generic 'OR' claim when it encompasses subject matter in the priority document. An answer of "no" would mark a move away from applying the test provided at reason 6.7 of G2/98 and mean that the toxic priority/divisional scenario could not occur.

However, if question 1 is answered in the affirmative, then questions 2 and 3 seek to establish if the test of G2/98 should be applied and how it should be applied. If that test is not to be followed, question 4 asks what test should be followed.

Question 5 is directed to the further issue of whether, even if partial priority may be refused for claim 1, it is possible for a parent to anticipate its divisional or vice versa.

Opportunities for the Enlarged Board of Appeal

The Enlarged Board of Appeal is now presented with the opportunity to endorse and clarify the test of G2/98 or develop a new approach to assessing partial priority.

The referring Technical Board of Appeal has provided the Enlarged Board of Appeal with a number of routes by which to potentially abolish the concept of toxic divisionals.

We can expect a decision from the Enlarged Board of Appeal in about a year or two. In the meantime we will of course keep our readers updated on the developments in this fascinating and fundamentally important matter. Should you have any questions please contact your usual D Young & Co advisor or the author of this article.


  1. Partial priority can be seen as a specific type of multiple priority wherein there is only one claim to priority, yet some subject matter has an effective date of the priority filing and some subject matter has an effective date of the filing itself. We will use the term partial priority in this article.
  2. The Board found that the example in the priority document contained an obvious typographical error with respect to the sulphur content of the fuel used in example 1, in that it should have stated 0.001% and not 0.01%.