2022 updates to EPO Guidelines for Examination – Partial priorities

2. Partial priorities

This forms part of a wider report on the 2022 updates to EPO Guidelines for Examination.

The previous section of the Guidelines at Part F-VI, 1.5, relating to multiple priorities, has now been now extended to explicitly cover partial priorities. The amended text is shown for reference below.

The section retains the previous examples about multiple priorities, i.e. explaining that alternative claimed embodiments A and B may have different priority dates, whether claimed separately or as alternatives in a single claim, if those embodiments are disclosed in different priority applications. If A and B are only disclosed separately in the priority documents, then a claim to the combination of A and B will generally not be entitled to the claimed priority date.

The amended Guidelines now define partial priority as referring to a situation in which only a part of the subject matter of a claim is entitled to the claimed priority date.

Partial priority was previously only alluded to briefly, with reference to the basic conclusions of EPO Enlarged Board of Appeal case G1/15 – this was a case that clarified how priority claims are dealt with where a claim encompasses alternatives within its scope, but without explicitly spelling them out. For example, a claim may refer to “metals” (which encompasses iron, zinc and other metals as alternatives), but not explicitly refer to “iron” or “zinc”, and this may become significant if the priority application only discloses the use of zinc but not iron. In this type of case, the alternatives are not claimed in such a way that they are explicitly separable, and this type of claim is referred to as a “generic ‘OR’-claim”.

The decision G1/15 clarified the previous Enlarged Board of Appeal decision G2/98, which referred to recognising partial priority where a claim defined a “limited number of clearly defined alternatives”. Following that earlier decision, the case law diverged to some extent in terms of how generously or strictly the Appeal Boards applied the test for being able to divide the claim into a number of alternatives (i.e. whether this only needed to be done conceptually, or whether limited alternatives needed to be clearly identified in the claim). Decision G1/15 clarified that a claim could be conceptually divided into a number of alternatives, which could then be assigned different priorities, even if these alternatives were not explicitly claimed.

The amended Guidelines expand on the test for partial priority, and have imported a section of the text from the G1/15 decision, even though this decision was issued over 5 years ago.

The imported passage sets out the steps of identifying the relevant subject matter in the priority document, determining whether this subject matter is encompassed by the claim of the subsequent application, and then conceptually dividing the claim into two parts (one corresponding to the subject matter disclosed in the priority document, and the other part being the remaining part) and assigning the priority to the first part.

The Guidelines then include a specific example of a case in which the priority document defines the use of a specific composition, whereas the later application claims the use of a composition defined in more generic terms.

The new text goes on to note that the same rationale applies to determining whether a priority application is the “first filing” for particular subject matter, which is a requirement for claiming priority from the earlier application in respect of that subject matter. In other words, the priority document may disclose a generic definition which encompasses a narrower earlier disclosure from a different document, such that the generic definition then has to be conceptually divided and is only treated as the first filing for a part of that disclosure.

Finally, the new wording includes a comment about partial priorities being transferrable separately, and that a consequence of this is that the assignor is then no longer able to continue claiming a partial priority right that has been assigned. The new text also states that “the transfer agreement … gives respective partial priority rights to the assignor and the assignee corresponding to two clearly distinct and precisely defined alternatives”. It is not clear whether the intention is to point out that the alternatives need to be very precisely defined in any transfer agreement, or that the separation of the ownership of different partial priorities has very significant consequences for what the respective owners can claim priority to, but it is clear that such transfers would need to be considered very carefully.

It is interesting to note that the EPO has felt the need to add more text from the 2016 decision G1/15, together with a new example, which may suggest that the issue of partial priority is one that has arisen more frequently in recent times, or that it was simply not considered to have been covered clearly enough in the previous text.

“”Partial priority” refers to a situation in which only a part of the subject-matter encompassed by a generic “OR” claim is entitled to the priority date of a previous application (G 1/15).

The previous application may have been filed in or for the same or different states or members of the WTO, but in all cases the earliest application must have been filed not more than 12 months before the date of filing of the European application. Subject-matter of a European application will be accorded the priority date of the earliest priority application which discloses it.

If, for instance, the European application describes and claims two embodiments (A and B) of an invention, A being disclosed in a French application and B in a German application, both filed within the preceding 12 months, the priority dates of both the French and German applications may be claimed for the appropriate parts of the European application; embodiment A will have the French priority date and embodiment B the German priority date as effective dates. If embodiments A and B are claimed as alternatives in one claim, these alternatives will likewise have the different priority dates as effective dates.

If, on the other hand, a European application is based on one previous application disclosing a feature C and a second previous application disclosing a feature D, neither disclosing the combination of C and D, a claim to that combination will be entitled only to the date of filing of the European application itself. In other words, it is not permitted to “mosaic” priority documents. An exception might arise where one priority document contains a reference to the other and explicitly states that features from the two documents can be combined in a particular manner.

According to G 1/15, entitlement to partial priority may not be refused for a claim encompassing alternative subject-matter by virtue of one or more generic expressions or otherwise (generic “OR” claim) provided that said alternative subject-matter has been disclosed for the first time, directly, or at least implicitly, unambiguously and in an enabling manner in the priority document. No other substantive conditions or limitations apply in this respect.

In assessing whether subject-matter within a generic “OR” claim may enjoy partial priority, the first step is to determine the subject-matter disclosed in the priority document that is relevant, i.e. relevant in respect of prior art disclosed in the priority interval. This is to be done in accordance with the disclosure test laid down in the conclusion of G 2/98 and on the basis of explanations put forward by the applicant or patent proprietor to support the claim to priority, in order to show what the skilled person would have been able to derive from the priority document. The next step is to examine whether this subject-matter is encompassed by the claim of the application or patent claiming said priority. If the answer is yes, the claim is de facto conceptually divided into two parts, the first corresponding to the invention disclosed directly and unambiguously in the priority document, the second being the remaining part of the subsequent generic “OR” claim not enjoying this priority but itself giving rise to a right to priority as laid down in Art. 88(3).

For example, if the priority document discloses the use of a specific composition whereas the application claims the use of a composition defined in more generic terms, two alternative groups of subject-matters are identified as being encompassed by the claim, even if the claim does not expressly spell them out:

– alternative (a), concerning the use of a specific composition (e.g. calcium salt of the active ingredient and tribasic phosphate salt in which the cation was multivalent) and

– alternative (b), concerning the use of a composition defined in more generic terms (e.g. acid form or acceptable salt thereof as the active, inorganic salt in which the cation was multivalent, wherein active ingredient and inorganic salt were other than calcium salt of the acid and tribasic phosphate salt in combination).

Alternative (a) is the subject-matter disclosed in the priority document, not defined as such in the claim but encompassed by it. Alternative (b) is the remaining subject-matter of the claim, which was not disclosed in the priority document. In such a situation, the subject-matter of alternative (a) enjoys priority whereas that of alternative (b) does not.

The rationale of decision G 1/15 also applies in the context of deciding whether an application from which priority is claimed is the first application within the meaning of Art. 87(1). Just as a priority application and a patent claiming priority from it may partially relate to the same invention, the priority application and an earlier application filed by the same applicant may also partially relate to the same invention. In that case, the priority application would be the first application in respect of only that part of the invention which is not the same as in the earlier application (T 282/12).

Partial priority may also be transferable separately. This, however, has consequences for the remaining priority right because the assignor is left with a limited right and may no longer keep claiming that partial priority (an applicant can only claim a right which they own). The transfer agreement of the partial priority gives a respective partial priority right to the assignor and the assignee corresponding to two clearly distinct and precisely defined alternatives.”

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