Tennessee Code Title 4. State Government § 4-5-303

(a) A person who has served as an investigator, prosecutor or advocate in a contested case may not serve as an administrative judge or hearing officer or assist or advise an administrative judge or hearing officer in the same proceeding.

(b) A person who is subject to the authority, direction or discretion of one who has served as investigator, prosecutor or advocate in a contested case may not serve as an administrative judge or hearing officer or assist or advise an administrative judge or hearing officer in the same proceeding.

(c) A person who has participated in a determination of probable cause or other equivalent preliminary determination in a contested case may not serve as an administrative judge or hearing officer or assist or advise an administrative judge or hearing officer in the same proceeding.

(d) A person may serve as an administrative judge or hearing officer at successive stages of the same contested case, unless a party demonstrates grounds for disqualification in accordance with § 4-5-302.

(e) A person who has participated in a determination of probable cause or other equivalent preliminary determination or participated in or made a decision that is on administrative appeal in a contested case may serve as an agency member in the contested case where authorized by law and not subject to disqualification or other cause provided in this chapter.