EPO: Subject-matter not originally disclosed

Marc Keschmann achieved a complete revocation of the patent in suit for our client before the EPO Opposition Division and was also successful in the appeal proceedings before the EPO Board of Appeal.

The applicant submitted a patent application titled "Portland limestone calcined clay cement" in 2010. The application was for a method of creating a high-strength cement that contained few lumps. After receiving the International Seach Report the appellant amended the feature "heat treated [...] in such a way that the heat treated clay material is substantially dehydroxylated" in original claim 1 to "produced at a temperature of between 500°C and 900°C". In 2018 the EPO initially granted the patent (EP 2 429 966 B1).

In 2019, Marc Keschmann filed an opposition on behalf of our client and requested that the patent was revoked in its entirety. The EPO Opposition Division decided to revoke the patent in 2022, because the amendment introduced subject-matter which extends beyond the content of the application as originally filed, thus being contrary Art 123 EPC.

The applicant filed an appeal and argued that the application as filed did not require full dihydroxylation and that the degree of dehydroxylation could be determined by analysing the obtained calcined clay according to the disclosed method. The applicant further argued that the heat treatment could be continued until the claimed dehydroxylation was reached, without undue burden, and that specifying time ranges would thus be an unwarranted restriction, since the heat treatment time span was dependent on the specific composition and the type of furnace used.

Finally, in 2024 the EPO Technical Board of Appeal dismissed the appeal and upheld the complete revocation of the patent in suit. The Board of Appeal established that the temperature range feature was different from the chemical reaction feature and that there was no basis in the application as originally filed for replacing the latter with the former. Further, the temperature range feature cannot implicitly be deducted from the chemical reaction feature either, because there is no evidence that any calcined clay produced at a temperature of between 500°C and 900°C is substantially dehydroxylated, irrespective of, for instance, the duration of the heat treatment. The applicant has not contested that dehydroxylation is essential to the production of calcined clay cement, and there are no convincing arguments as to why this feature could be omitted. 

The patent would have implied a de facto monopoly on the production of Portland composite cement of the normed class CEM II/C-M(Q-LL). Therefore, the successful revocation is an important achievement and establishes our client’s freedom to operate. (EPA Technical Board of Appeal, 26 February, 2024, T 1657/22 – 3.3.05)