Forget analyses phraseological units sourced in the linguistic examples found in the second edition of the Dictionnaire de droit privé et lexiques bilingues (Paul-André Crépeau Centre for Private and Comparative Law, 1991). The author shows how his review of this sample supports the view that phraseological units can be divided into two categories: lexical and conceptual. His definition of phraseological units is founded on idiomaticity, with what constitutes a phraseological unit in a given context being left ultimately to the determination of specialists in the given field. This study demonstrates the need for re-appraisal of the relationship between legal and ordinary language.