<i>If I understand what you&#x27;re saying correctly, this happens all the time: for instance, it has happened every time an answering machine tape has been entered into evidence.</i><p>No. An answering machine tape is not a person at criminal trial.<p>&gt; nor shall be compelled in any criminal case to be a witness against himself<p>You are talking about physical evidence; an answering machine tape, presumably recording some prior conversation, is a physical artifact that already exists. In no way can you construe examining a pre-constructed physical artifact as compelling a criminal defendant to witness against their self [It would imply criminal defendant is somehow the physical artifact itself.].<p>If I am not mistaken, &#x27;witness&#x27; refers to making real claims about events at trial. Making real claims that one performed criminal activities at trial <i>can</i> be construed as evidence. An individual may conceal that evidence by not revealing it, and I don&#x27;t believe US law allows any way to reveal such evidence.