Untangling the complexities of legal documentation is an imperative need for non practitioners of the legal profession. The terminology used in the domain is complex and it usually requires expert knowledge to be fully understood, since the legal framework is constantly being updated and the meaning of terms vary accordingly. Non-proprietary Automatic Terminology Extraction (ATE) tools are required in this particular domain in which documents contain private and sensitive data. This paper describes methods for obtaining accurate legal terms from labour law corpora, overcoming the difficulties present in the area, and also analyses the peculiarities of the legal jargon, specifically, in Spanish language. The performed experiments, executed with JATE, a well-known open source library in the ATE literature, are still preliminary, but promising.