A number of studies have demonstrated the clash of discourse worlds that occurs when the law and the lay client meet, due to the specific expectations and assumptions of relevance of the law which conflict with the everyday discourse practices of the lay client. Such a clash often causes frustration on both sides, and more seriously, can have a negative impact on the outcome of legal cases. This paper has applied the principle of lawyer client discourse differences to the situation where the client is a non-English speaker requiring the intervention of an interpreter. This paper bases its hypothesis on authentic data of Spanish-English interpreted proceedings and reports the main results of discourse alterations by the interpreter.