I have written a lot about partial priority over the past few years (to see all of my posts on the subject, click here), and have always allowed conflicting views to be expressed about the subject, for example in various comments on the subject as well as in this post that expresses a view opposed to my own. The discussion to date has, however, been largely about which side should be taken on the issue of whether partial priority should be allowed for a generic claim, i.e. whether a broad or narrow view should be taken, and always within the framework of the EPC and associated case law. This will, of course, determine the outcome of the currently pending G 1/15 case. There are, however, other perspectives that can shed different light on the subject, one of which has been recently published in epi Information.
The article, titled "The History of Partial Priority System of the Paris Convention", by Kazuo Shibata, a Principal Examiner at the Japan Patent Office, goes through the long history of claiming priority for patent applications, going back to the Great Exhibition of 1851 in London. The author then provides details of the various legal developments, and reasoning behind them, that occurred throughout the world up to the establishment of the European Patent Convention in 1973. A key theme of the article, and what appears to be a favourite subject of the author, is what is described as the "umbrella theory" of priority (illustrated by the picture here, taken from the article). This theory, which apparently originated in Germany, was intended to protect an application from being affected by disclosure of the content of its priority document if it covered a combination of features that included subject matter in the priority document. Interestingly, this protects a combination of A+B as well as A OR B from being attacked by disclosure of A in the priority document.
As the author notes, umbrella theory has not been widely taken up, and appears now to be inconsistent with UK and EPO case law. It does, however, provide an interesting different perspective on the question of whether an invention can enjoy partial priority. The author ends with a scenario that he asks the reader to consider, which is similar to some of the scenarios considered in G 1/15. I my view, the scenario makes sense whether the broad view of partial priority is taken or the umbrella theory view is taken, but the author does not yet have an answer himself. I wonder if anyone else can take a view? Is umbrella theory simply outdated and no longer relevant, or does it have a part to play?