G1/15 – The End of “Poisonous Divisionals”

On 29 November 2016, the decision in case number G 1/15 was announced by the Enlarged Board of Appeal of the European Patent Office (EPO). The decision has made clear that so-called “poisonous divisionals” cannot exist.

The background:

The potential for a divisional patent application to be cited against its own parent application arose from several decisions before the Technical Boards of Appeal of the EPO. This concept became known as the problem of “poisonous divisionals”. The term “toxic priority” was also used.

T 1496/11

Technical Board of Appeal Decision No. T1496/11 was the decision that started it all.

The invention in that case related to banknotes comprising a transparent window that could function as a lens so that, when the banknote was folded in two, an area of micro-printing on the banknote could be viewed through the lens.

The priority application disclosed only a “printed or embossed” feature to be viewed. The divisional application disclosed the same “printed or embossed” feature. Claim 1 of the parent application, however, referred more broadly to a “feature which can be inspected, enhanced or optically varied by the optical lens”.

The broader wording of the parent application covered other possibilities that were not disclosed in the priority application, such as a window acting as a filter or polariser.

The Board of Appeal in T 1496/11 held that the broader Claim 1 of the parent application was not entitled to the priority date, and therefore lacked novelty under Article 54(3) EPC over the narrower embodiment disclosed in its published European divisional application (which was entitled to priority).

T 1496/11 thus led to the risk that a published divisional application could be cited against a later application claiming that priority, if the claims of the later application were broader than the subject matter disclosed in the priority application.

Referral to the Enlarged Board of Appeal

Some later decisions supported the findings of T1496/11. Some other decisions did not.

Due to uncertainties arising from the different findings in different Appeal Decisions at the EPO, the Enlarged Board of Appeal of the EPO, which is the highest body of the EPO, was asked to consider the situation.

G1/15 Decision

On 29 November 2016, the decision in G1/15 was announced, as follows:

“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.”

Take away points

G1/15 makes clear that a claim to priority cannot be lost by broadening a feature disclosed in the priority application.

Priority will always be valid in respect of the narrower features disclosed in the priority application that will be covered by the broader feature.

Poisonous divisionals cannot exist.

Divisional patent applications in Europe are safe to file.


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