All EU member states, except for Spain, Croatia, Czech Republic, and Poland, are expected to participate in the unitary patent protection system and the UPC. Spain will not be participating in the UPC or the unitary patent protection system. Croatia became a member of the EU after the adoption of the UPC Agreement and the two EU regulations on unitary patent protection, and has not yet decided whether or not to participate. Poland and Czech Republic participates in the two EU regulations on unitary patent protection, but does not intend to ratify the UPC Agreement. This means that the the two countries will in effect be standing on the sidelines.
Not all countries will participate from the outset, and it will probably take some time before the UPC will enter into force for all countries having joined the UPC Agreement. This will depend on when the individual countries ratify the UPC Agreement, see more information about when the UPC will enter into force here.
The UPC will be composed of a Court of First Instance and a Court of Appeal. The Court of First Instance will have a central division and a number of local and regional divisions. The central division will be seated in Paris, and a section will be located in Munich. A section was previously supposed to have been located in London, but after Brexit it's unclear what will happen to the London section. The Court of Appeal will be seated in Luxembourg.
Local divisions of the UPC may be set up in the individual participating countries. A participating country may establish up to four local UPC divisions (the requirement is at least 100 patent cases a year per local division if more than one local division is to be set up). UPC participating countries may also join forces to set up a regional division. At present, only Sweden and the Baltic countries have done so.
Malta and Luxembourg have announced that they will use the central division. Bulgaria and Portugal are expected to participate, but have not yet made any announcement concerning local/regional division. To this should be added a number of primarily Eastern European countries which have not yet ratified the UPC Agreement or made a formal announcement concerning participation.
Unless a country has established a local division, the central division of the UPC will be used for the actions that would otherwise have to be brought before the local division.