Our chemistry department drafted and filed an opposition on behalf of RIO TINTO ALCAN INTERNATIONAL LIMITED, based mainly in Montreal and Melbourne, against European Patent EP 3266904, owned by TRIMET ALUMINIUM SE based in Germany.

This patent was directed on control method for operating a cell of a molten salt electrolysis system, especially for producing aluminum, and the molten salt electrolysis system comprising a control device implementing the control method thereof. This purpose of this method was to carry out reliably a molten salt electrolysis for producing aluminum in the event of variable availability of electrical energy in the power grid without impairing its efficiency.

In our opposition brief, we challenged novelty and inventive step on documents not cited during the examination prosecution of the corresponding European patent application. Furthermore, we tackled the sufficiency of disclosure of some of the features of the control method and the clarity of one feature of the control method, and pinpointed that some of the amendments made during the patent prosecution were inadmissible.

During the opposition proceedings, the patent proprietor filed twelve auxiliary requests. In the oral proceedings, the Opposition Division decided that auxiliary request n°1 was new and implied inventive step in view of the cited documents.

We filed an appeal against the decision of the Opposition Division on March 8th, 2024 and highlighted the reasons why the decision shall be dismissed on the grounds of both novelty and inventive step. Especially, we pushed back the claim construction made by the Opposition Division to emphasize why D4, cited in the opposition brief, should anticipate the novelty of claim 1 of the first auxiliary request as all the steps of the control method were disclosed. We pushed back the claim construction made by the Opposition Division.

The Board of Appeal issued a preliminary opinion wherein they shared our reasoning elaborated in our statement setting out the grounds of appeal. Especially, they opined that pending claim 1 of the first auxiliary request was not new over D4. Furthermore, the Board of Appeal highlighted that the patent proprietor submits the same auxiliary requests as those in the first instance without substantiating them. Indeed, the Board Opinion pointed out that the patent proprietor failed to elaborate in its perfunctory response the reasons why the auxiliary requests should overcome the objections raised in our statement setting out the grounds of appeal.

The oral procedure took place on April 7, 2025.

We represented RIO TINTO ALCAN INTERNATIONAL LIMITED during the oral procedure.

The Board of Appeal completely overturned the decision of the Opposition Division based as claim 1 of the first auxiliary was considered not to be new over D4. The Board of Appeal further did not admit the auxiliary requests that were filed but not substantiated in response to our statement setting out the grounds of appeal. Thus, the Board of Appeal revoked the European Patent in its entirety (decision T0007/24).