- GPTO: the hearing is handled by a single examiner (the same who also handled the written procedure)
- EPO: the hearing is handled by a panel of three examiners (the primary examiner in charge of the written procedure and two further examiners)
So if you cannot convince the EPO primary examiner, you still have a chance of convincing the other two members of the examining division.
Therefore, your European patent attorney should always plead his case so that the two members less involved in the case can easily follow and make up their own minds.
I’ve seen countless cases where the primary examiner finally gets overruled by the other two members. The length of the examining division’s deliberations while you wait outside is a good indicator of the extent to which they disagree 😉