Assuming an applicant has indicated a desire to have a patent valid in all European countries and elects to have the application examined by the European Patent Office, a regional patent office, the patent that is ultimately granted is valid:
“upon registration in each country that supports the European Patent Office”
Why? The European Patent Office (EPO) is a regional patent office that examines patents under the European Patent Convention (EPC). The EPO provides a centralized searching and examination authority for the signatory countries. In such case, the patent application will be examined in each country and may have different claims granted. There are 20 European countries that subscribe to the EPC, and membership to the EPC is not limited to the members of the European Union. A European patent is in force only in the countries designated by the applicant where registration (often called conversion) takes place. Conversion involves filing a translation of the patent, if necessary, to the official language(s) of the countries where enforcement is sought and payment of the national fees required. Alternatively, an applicant desiring protection in EPC countries can apply separately to each country’s patent office. Other regional patent offices with similar systems to the EPO may be found in Africa (ARIPO and OAPI) and in Eastern Europe.