EPO Boards of Appeal Approach to Partial Priorities

EPO DECISION T0260/14

Following the Decision of the Enlarged Board of Appeal at the EPO in G1/15 regarding partial priorities, the EPO Technical Boards of Appeal have started applying the principles from this decision when deciding whether claims should be entitled to partial priority. This case sets out a two-step test which we expect to be used by future Boards of Appeal when examining partial priorities.

The applications relate to compositions for dental impression materials. Claim 1 of the granted patent read as follows:

"A dental impression material comprising a base paste and a catalyst paste, wherein the base paste comprises at least one polymerizable polyether material with a linear backbone having no side chains which is selected from the group consisting of

a) polyethers with at least one aziridino group,

b) polyethers with at least one olefinically unsaturated group and a compound with at least one SiH group and

c) polyethers with at least one olefinically unsaturated group and at least one SiH group and

d) polyethers with at least one alkoxysilyl group;

e) polyethers with at least one olefinically unsaturated group

and 0.1 to 15% by weight of a fluidity improver, the fluidity improver being a random copolyether of ethyleneoxide and at least one more alkyleneoxide which is not ethylene oxide, the copolymer comprising at least about 50% of structural elements from ethylene oxide as a fluidity improver, the fluidity improver having a molecular weight Mw in a range of 100 to 1900, and wherein the catalyst paste comprises at least one initiator or catalyst or both for initiating or catalyzing the polymerization of the at least one polymerizable polyether material."

At opposition, the opponent argued that as claim 1 of the patent as granted was different from claim 1 in the priority application, priority could not be validly claimed. Consequently, the published priority document became prior art under Art. 54(3) EPC and a working example disclosed in the priority application anticipated claim 1 of the granted patent.

At appeal, the Technical Board of Appeal applied the Enlarged Board Decision, G1/15. In applying the decision, they stated that there is a two-step test to deciding whether claimed subject-matter can be entitled to partial priority.

Firstly, it is necessary to determine what is disclosed in the priority applications by applying the principles laid out in G2/98 (namely what is clearly and unambiguously disclosed). In determining this, it is necessary to look not only at the claims of the priority application but also at the description.

Secondly, one must examine whether this subject-matter is encompassed by the claim of the patent in question. As G1/15 is concerned with generic “OR”-type claims, it is also essential to ensure that the claim in question is such a type of claim. Therefore, the subject-matter disclosed in the priority application must be alternative subject-matter by virtue of a generic “OR”-type claim. Although it is not necessary whether the subject-matter is expressly identified in the claims as an alternative, it must be envisaged that numerous alternatives exist.

In this case, the subject-matter relied on by the opponent as anticipating the claim was a working example. This working example clearly fell within the scope of the disputed claim and it was accepted that the working example was just one specific embodiment of the claim and that other alternative examples with different variants were possible and would fall within the scope of the claim.

Accordingly, the claim was entitled to partial priority and the priority document was not considered to be novelty-destroying pursuant to Article 54(3) EPC.

At appeal, the Opponent submitted that the situation in this case was distinguished from the case in G1/15, as in the present case, the scope of at least one of the features in the claim of the patent was narrower than the scope in the priority application. The priority application disclosed a molecular weight for the fluidity improver of 100-3800, whereas in the patent, claim 1 stated that its molecular weight was 100-1900. The Opponent argued that in G1/15 the disclosure in the priority document was narrower in all respects that the granted patent. The Board considered this issue irrelevant as the question being addressed was whether the part of claim 1 which concerns the working example was entitled to claim priority from the earlier application.