At the European Patent Office (EPO), the question of entitlement to partial priority appears when a claim covers alternative subject matters, and can appear after the scope of a claim is broadened by amendment, consequently encroaching on prior art. Such a situation can occur, for example, by the broadening of a chemical formula, of a range of values, or of chemical compositions relative to the disclosure of the priority document. How is the EPO testing the problem in case law?
G1/15 — the test for partial priority
Earlier this year, the Enlarged Board of Appeal of the EPO issued a decision in case G1/15 in relation to partial priority. The decision includes guidance on how to determine whether part of a claim is entitled to a claimed priority date when the claim “encompasses alternative subject matters by virtue of one or more generic expressions or otherwise”.
Claims of this type are sometimes known as generic OR claims. The guidance takes the form of the following two-step test:
- Determine the subject matter disclosed in the priority document that is relevant.
- Examine whether this subject matter is encompassed by the claim of the patent claiming priority.
If the relevant subject matter is encompassed, then the claim is conceptually divided: the encompassed subject matter is entitled to partial priority, while the remaining subject matter is not entitled to priority (but itself gives rise to the right of priority).
T0260/14 — the new test applied
In April this year, the two-step test was applied for the first time by the Technical Board of Appeal in T 0260/14.
The opponent argued that claim one of the patent was not novel over prior art document D5, published after the claimed priority date, and that claim one was not entitled to its claimed priority date.
The patentee argued that claim one of the patent was entitled to partial priority in respect of a part of the claim concerning a working example contained in the priority document; therefore, D5 was not prior art, and claim one was novel.
Having used step one to determine that the relevant subject matter was the working example, step two involved the board having to decide whether the working example could be considered alternative subject matter by virtue of a generic OR claim.
Claim one was directed to a material comprising a base paste and a catalyst paste. In the description, the two pastes were described using generic features. It was therefore decided that the working example was to be considered one specific embodiment of the claim and that multiple alternative working examples would be possible, with different variants falling within the generic definitions of claim one. Therefore, the working example was considered alternative subject matter falling within the scope of claim one, and claim one was considered entitled to partial priority on that basis. The opposition was rejected.
Better for the patentee?
G1/15 appears to provide clearer guidance on determining entitlement to partial priority. This clarity will enable patent proprietors to benefit from claiming partial priority while safely avoiding the complex problem of so-called poisonous priority.