In order for a translation to be accepted, it must be done by a sworn translator validated by the Ministry of Foreign Affairs (Ministerio de Asuntos Exteriores). The best way to guarantee that a translator has been in fact validated by the Ministry is to verify it by checking the official list of sworn translators. This list must be available to the public in some of the offices of the Ministry of Foreign Affairs.

In the next website, you can also find a list given by the Ministry with the names and details of the practising sworn interpreters to be found in Spain: http://www.mae.es > tablón de anuncios (Bulletin Board. See vertical menu on the left) > oposiciones y concursos (civil service examinations)  > intérpretes jurados (sworn interpreters.).