Rule 614 - Calling and Interrogation of Witness by Court(a) Calling by court The court may not call witnesses except in extraordinary circumstances or except as provided for court-appointed experts in Rule 706, and all parties are entitled to cross-examine witnesses thus called.(b) Interrogation by Court The court may interrogate witnesses.(c) Objections Objections to the calling of witnesses by the court or to interrogation by it may be made at the time or at the next available opportunity when the jury is not present.Advisory Commission Comments.
Ordinarily the trial judge may question but not call lay witnesses. Rule 706 details procedures for calling court-appointed expert witnesses in a bench trial.
In questioning a witness, the judge must avoid "commenting on the evidence"in violation of the Tennessee Constitution, Art. VI, Sec. 9.