EPO: Flexibility in Delimiting Two-Part Claims

When drafting patent claims in two-part form, the question of correct delimitation regularly arises. According to Rule 43(1) EPC, the delimitation must be made against the state of the art. However, this does not mean that the delimitation must necessarily be made against the closest state of the art from which the decision on the merits starts. Rather, the delimitation can also be made against another suitable state of the art. (EPO-BoA 29.09.2025, T 644/23)