Tenn. Code Ann. § 40-11-114: Contents of written undertaking

(a) Bail, when not given in open court, is given by a written undertaking, containing the conditions of release, the agreement of the defendant to appear in the court having jurisdiction of the offense as directed by the court and/or an amount to be paid for nonappearance, signed by the defendant, and if made under § 40-11-122(2) , signed also by court-approved and sufficient surety or sureties. The written undertaking must be approved by the officer taking it.

(b) An electronically transmitted facsimile copy of a written undertaking shall have the same legal effect as the original written undertaking. An electronically transmitted facsimile copy of a written undertaking signed by the defendant shall have the same legal effect as the written undertaking signed by the defendant.