The Preparatory Committee of the Unified Patent Court (UPC) has given their opinion that no provisions of the UPC Agreement should apply to opted-out European patents without unitary effect in the national courts. This is a clarification on the interpretation of Article 83 of the UPC Agreement. Article 83 provides a transitional period where an owner of a European patent without unitary effect can opt-out of the jurisdiction of the UPC.
However, some thought that the UPC Agreement (as a whole, including the parts relating to substantive patent law) would still apply to opted-out European patents without unitary effect in the national courts. This would have the effect of enforcing harmonisation of national patent law. The Preparatory Committee stated in their interpretative notice it was not intended by the contracting states for it “to be obligatory to harmonise patent law”. So, the Preparatory committee believes that opting out of the jurisdiction of the UPC means opting out of the whole UPC Agreement.
For the UPC view see here.