Tennessee Code Title 65. Public Utilities and Carriers § 65-2-109

(1) The commission shall not be bound by the rules of evidence applicable in a court, but it may admit and give probative effect to any evidence which possesses such probative value as would entitle it to be accepted by reasonably prudent persons in the conduct of their affairs; provided, that the commission shall give effect to the rules of privilege recognized by law; and provided further, that the commission may exclude incompetent, irrelevant, immaterial or unduly repetitious evidence;

(2) All evidence, including records and documents in the possession of the commission of which it desires to avail itself, shall be offered and made a part of the record in the case, and no other factual information or evidence shall be considered in the determination of the case. Documentary evidence may be received in the form of copies or excerpts, or by incorporation by reference;

(3) Every party shall have the right of cross-examination of witnesses who testify, and shall have the right to submit rebuttal evidence;

(4) The commission may take notice of judicially cognizable facts and, in addition, may take notice of general, technical, or scientific facts within its specialized knowledge. Parties shall be notified either before or during the hearing, or by reference in preliminary reports or otherwise, of the material so noticed, and they shall be afforded an opportunity to contest the facts so noted. The commission may utilize its experience, technical competence, and specialized knowledge in the evaluation of evidence presented to it; and

(5) The burden of proof shall be on the party or parties asserting the affirmative of an issue; provided, that when the commission has issued a show cause order pursuant to this chapter, the burden of proof shall be on the parties thus directed to show cause.