Rule 104 of the Tennessee Rules of Evidence permits the trial judge significant leeway in what may be considered in determining what evidence can be admitted at trial. It provides as follows:
Rule 104. Preliminary questions. —(a) Questions of Admissibility Generally. —Preliminary questions concerning the qualification of a person to be a witness, the existence of a privilege, or the admissibility of evidence shall be determined by the court, subject to the provisions of subdivision (b). In making its determination the court is not bound by the rules of evidence except those with respect to privileges.
Here is subdivision (b):