Based on a monolingual comparable corpus made up of judgments delivered by the Spanish Supreme Court and by the Court of Justice of the European Union, this paper presents a case study on complex prepositions considered as a specific discourse feature of these two varieties. In spite of the initial hypothesis, according to which a higher percentage of these phraseological units was expected to be found in national texts, the results of the analysis show that EU judgments contain a higher percentage of complex prepositions, in line with the results obtained by Biel on a number of different legal genres in Polish. From a qualitative perspective, the study also compares similarities and differences in the phraseological patterns used in the two subcorpora, and hints at the untypical use of some units in the EU subcorpus, traditionally considered as traces of ‘translationese’, but functionally interpreted in this study as examples of contact-induced features characterising Spanish Eurolect.