When a new country becomes a member of the EU, the national language of that country normally becomes an official EU language. The decision on this is taken by the EU Council of Ministers. This ensures that individual EU citizens are able to use the same language in any contacts with the EU and its institutions as they do when dealing with their national authorities at home.
By the same token, all new legislation adopted by the EU is translated into all official languages so that any interested citizens across the Union know immediately what the new law is about and how it affects them. All language versions of an EU law have the same legal value.
In this way, the EU ensures that there is no discrimination between citizens whose languages are spoken by a large number of people and others using less widely spoken ones. In the European Parliament, for example, members are free to address the assembly in the language of the people they represent. Slovenian members are just as entitled as German ones to speak the language of those who voted for them. The EU strives to protect this linguistic diversity and promote the learning of languages.
All 23 official languages of the EU are accepted as working languages, but in practice only three are used most often: English, French, and German.