The present research explores the impact that cognates, that is, words which share formal and often semantic features in the L1 and the L2, may have on the understanding and acquisition of legal English terminology. To that end, a DDL experiment was carried out using two corpora, one of them the BLaRC, an 8.85 million-word collection of judicial decisions issued by British courts, and the LACELL, a general English corpus of 21 million words. 56 first-year Spanish Law students were asked to translate 12 legal terms, 10 of which were English/Spanish cognates. The results showed that, as it was indeed expected, the higher the students’ proficiency level (they were administered a level test prior to the experiment), the higher their rate of success in providing correct answers. This was so both for the general and specialised fields proving that partial semantic equivalence between cognates did pose certain difficulties in their understanding even for the higher level groups.