Partial Priority In European Patent Applications – No, Mother You Can’t Eat Your Babies:


By Lawrence Hoffman

J.D., B.Sci. Electrical Engineering and Comp. Sci., U.S. Patent Attorney


A recent order of the Enlarged Board of Appeals of the EPO in G 1/15 appears to have set to rest a significant issue under the European Patent Convention (EPC) – the so-called “poisonous priority” that had been plaguing efforts to implement a comprehensive patent protection strategy. The reasoned decision has not yet been published but hopefully will be soon. We will report further at that time on the details. The patent being opposed was a divisional of an earlier one. The division claimed a genus while the parent only disclosed a species within the genus. The Enlarged Board’s order, issued on 29 November, reads:

Under the EPC, 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 other words, a generic claim encompassing alternative subject matter may not be refused partial priority, provided the alternative subject matter has been directly, at least implicitly, and unambiguously disclosed in the priority document. According to the board, its reasoned decision will follow. We will report further when it is published.



For those not having a detailed familiarity of EPO practice, some procedural and substantive background will help demonstrate the significance of this development.

Procedurally, appeals on substantive matters relating to the granting of European patents and oppositions under the EPC are decided by Technical Boards of Appeal comprised of two members having technical training in the relevant subject matter, and one member having a legal background.

The EPC also establishes an Enlarged Board of Appeal, one of whose functions is to decide cases referred to it by one of the technical boards appeal or by the EPO President for a decision on an important point of law or to secure uniform application of the law where two boards of appeal have given different decisions on the same question. In referral cases the Enlarged Board of Appeal is composed of five legal members and two technical members.

Substantively, a well-designed IP strategy should include establishing the earliest possible priority dates for your patent applications, trademark registrations, etc. If two parties file applications to protect essentially the same invention, trademark or other intellectual property, the one who files first will generally prevail.

Similarly, the novelty and in some countries, the inventiveness (or non-obviousness) of the claimed subject matter in a patent application will be judged against the state of the art as of the application filing date. A patent application, or a first application, should therefore be filed as soon as an enabling disclosure, i.e., one from which a person of ordinary skill in the art can make and use the invention, can be generated.

A practical way to get an early priority date is to file a U.S. provisional application. The official fees are low, provisional applications are never published and therefore can never be prior art against later applications filed to protect improvements or other evolving (perhaps broader) aspects of the invention, and don’t start the patent term clock running. As long as you follow up with a U.S. nonprovisional application or file an international (PCT) or other non-U.S. application within 12 months, you get the filing date of the provisional as your priority date for the followup filings.

In many cases, a PCT application or applications in only a few individual countries of interest) will be filed within the 12 month priority period rather than a U.S. nonprovisional application. In the case of a PCT application, the applicant will have another priority window (typically 30, 31, or sometimes 32 months from the earliest priority date claimed) to seek patent protection in one or more of the 151 countries and regions (i.e., groups of countries such as the European Union) that are parties to the PCT treaty.

Another option if one is interested in seeking protection only in Europe, or perhaps just in Europe and the U.S., is to file a U.S. nonprovisional, and follow up with an application under the European Patent Convention (EPC). If the EPO allows the application, the patent can be validated in one or more of the 28 EU countries. In any of these situations, the priority date of the first filing will pass through to the subsequent applications if the disclosure meets the enablement requirements noted above. For convenience, we will sometimes refer below to all of these collectively as the “first followup”.

Things get a bit more complicated when the invention evolves after the initial filing. Assume you have filed a U.S. provisional application that describes the invention as comprising features A, B, and C. Further work then reveals that feature A can be optimized (for example, in terms of a parameter range) as feature A* and that feature B has been described too narrowly (e.g., you have found that a substance B is part of a genus B* of workable substances), or your process is usable to manufacture B but also D, E, F, etc.).

If you discover these aspects within the 12 month provisional window, you can file a second provisional, disclosing the original and the new information. Alternatively, you can just include the new information in the first followup application. Either way, the first followup should include a priority claim to any provisional or other prior application that discloses the original subject matter. The priority claim should also be carried over to a national phase (NP) application derived from a PCT, and to divisional or other continuing applications. That will assure that claims directed only to the original information will have the earliest possible priority date. Of course, claims including the new subject matter will only get the date of the application in which the new subject matter was first disclosed.

A European application (whether filed directly or derived from a PCT application) creates the possibility for an even broader benefit. Under Article 88(2) of the EPC, multiple priorities or “partial” priorities may be asserted for a single claim! Article 88(3) clarifies that where multiple priorities are claimed, a particular claimed priority date applies to respective claim elements according to the date of the priority application in which the element is disclosed.

Thus, if a claim in an EP application recites elements A and B that are first disclosed in an application having an effective date P1, and element C is first disclosed in an application having a later effective date P2, elements A and B will get date P1 and Element C will get date P2.

But, as it is said, the devil is in the details. If features A and/or B are recited in the broad claims and are explicitly disclosed in the P1 application, priority as to those features won’t be questioned. However, what about a situation in which the features in question are not disclosed verbatim in the priority application? How is it determined whether priority will be recognized?

A 1998 opinion of the Enlarged Board in G 2/98 summarized the state of the law at that time. Historically, the right to claim priority is determined by the extent to which the subject-matter claimed in the later application had been at least implicitly disclosed in the first application. This was true if claims of the later application had been broadened in relation to the disclosure of the previous filing, and also where the invention was more narrowly defined in the European patent application than in the putative priority previous application.

In another case, T 73/88 priority was recognized even though the main claim contained an additional technical feature not disclosed in the priority application because the feature was not related to the function and effect, i.e., to the character and nature, of the invention. That rule had been followed in some subsequent cases. However, in other cases, the requirement for at least implicit disclosure was maintained.

Regarding multiple priorities, the legislative history as described in G 2/98 makes a distinction between so-called “AND”-claims and “OR”-claims. An “AND”-claim is one where a first priority document discloses a feature A, and a second priority document discloses a feature B for use together with feature A, and a claim directed to A+B. That claim cannot enjoy a partial priority from the first priority date, because the invention A+B was disclosed only at the date of the second priority document”. Besides, the application of the “umbrella”-theory would manifestly be at variance with Article 88(4) EPC.

An “OR”-claim is one for which a first priority document discloses a feature A, and a second priority document discloses a feature B for use as an alternative to feature A. Then, a claim directed to A or B can enjoy the first priority for part A of the claim and the second priority for part B of the claim. It had further been suggested that these two priorities may also be claimed for a claim directed to C, if the feature C, either in the form of a generic term or formula, or otherwise, encompasses feature A as well as feature B, provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters.

In the end, G 02/98 held that the determining allowance of priority required a narrow or strict interpretation of the concept of “the same invention”, equating it to the concept of “the same subject-matter” to which the feature of the claim in question needed to be directed.

In the present case G 1/15, the claim for which partial priority was sought recited in generic terms what had been disclosed only in terms of a species in the claimed priority document, i.e., the “OR” type claim. If priority was denied, the earlier application would have been prior art against the later application and would have “poisoned” it. The board categorically rejected the argument that separate publication of the content of the first application (e.g. in a divisional application) can be considered novelty destroying with respect to the broader subject matter i.e., the genus, since only a species of the genus was disclosed in the first application. Removal of this possible impediment to a sound patent protection strategy is definitely welcome news for patent owners and applicants.


News & publications:
More Newsletters: