Catalan, Basque and Galician can now be used in the European Court of Justice

There are quite a few articles on this in Spanish that pretty much say the same thing, so let's go with...this one.

Catalan, Basque and Galician can be used starting tomorrow (=27 April) in the European Court of Justice, based in Luxembourg...then it goes on about an administrative agreement that has made the usage of recognized regional languages in this way possible, and that Spain is the first country to utilize this. With this citizens can send correspondences to the court in any of Spain's official languages and receive a reply in the same language.

Catalan and Galician are both Romance languages so receiving and sending letters in those two should be a pretty easy matter (there was even a common Galician-Portuguese language in the Middle Ages), but Basque is completely different and would require relying entirely on Basque native speakers, since no one else would be able to manage the documents, and I imagine this would place a bit more burden on those handling the correspondences to be accurate. I would imagine for example that any correspondences coming in in Galician or Catalan could easily be looked over by someone that doesn't necessarily know the language as a mother tongue to get an idea what the subject is after which it would get forwarded to the person in charge, but Basque doesn't look like other European languages so letters in Basque would just go straight to the native speaker in charge. At least, that's the way I imagine it would work.