Unexpected and easy ways to invalidate your priority claim in Europe

I came across this interesting article regarding a recent decision from the European Patent Office's (EPO's) Boards of Appeal relating to priority. In Europe, for a priority claim to be valid, amongst other criteria, a later filed priority claiming application must be to the "same invention" as an earlier filed priority application. The decision, T 1303/18, highlights the strict approach taken by the EPO when assessing whether the priority application and the priority claiming application relate to the "same invention".  

One of the easiest ways a priority claim can be found invalid in Europe is through making minor amendments to the specification of a priority claiming application, where these minor amendments do not appear in the specification of the priority application. This is because the EPO apply their strict added matter test when determining if the priority claiming application is to the "same invention" as the earlier filed priority application (again confirmed in T1303/18). This means that even minor amendments, such a changing the words used to describe a particular effect or apparatus, could result in an invalid priority claim.

To illustrate, imagine a hypothetical priority document that describes and claims "a robotic arm configured to operate in a warehouse to package goods". A follow up priority claiming application that claims "a robotic arm configured to operate in a factory to package goods" could struggle to have priority in Europe, unless there is a direct and unambiguous disclosure in the priority document that the robotic arm could operate in a factory to package the goods. In this hypothetical case, the wording may have been changed because it "sounds" better to the applicant, or translates better into other languages than warehouse. Indeed, from a patentability view there is no significant difference between a warehouse and a factory. Yet this minor different could cost the applicant priority in Europe.  

Another example of an amendment that could result in an invalid priority claim is changing the dependency of the claims. For example, the priority document may be filed with singly dependent claims (e.g. each dependent claim is dependent on only the independent claim). If the follow up priority claiming application is filed with the same claims, but with multiply-dependent claims, certain combinations of those dependent claims may not have priority, since the priority document did not claim those combinations. That is, it would have to be demonstrated that the combination of claims was directly and unambiguously derivable from the priority document in order for priority to be valid. As noted above, this can be challenging given the EPO's strict rules regarding what is directly and unambiguously disclosed in a document.

The take home message here is where possible ensure that the priority claiming application comprises the same content as the priority application. If the priority application describes a widget, use the term widget in the priority claiming application, i.e. do not change the words used to describe features of the invention. If it is necessary to describe new aspects of the invention in the priority claiming application, try to do so without deleting the previous description from the priority application. If it is expected that further applications will be filed in jurisdictions that allow multiply-dependent claims, such as Europe, it is good practice to file multiply-dependent claims in the priority application. When filing the initial priority application in countries where multiply-dependences are not allowed (or attract unduly expensive claims fees), it is good practice to instead add the claim language to the end of the description as a set of numbered clauses. In this way, the numbered clauses can have multiply-dependencies to the other clauses, and which can then be used to support a priority claim to multiply-dependent claims when filing a follow up priority claiming application in Europe.  

If you would like any advice on priority in Europe, please do get in touch.