Tennessee Code Title 24. Evidence and Witnesses § 24-4-102

(a) All witnesses attending, under summons, any court of record in any county in this state other than the county in which the witness or witnesses live shall be entitled to receive reimbursement for lodging and meals at a rate allowable under the state comprehensive travel regulations in effect at the time such travel expense is incurred. In addition thereto, the witness shall also receive reimbursement at a rate allowable under the state comprehensive travel regulations in effect at the time such travel expense is incurred for each mile traveled in going to and returning from such court.

(b) In addition to the mileage reimbursement allowed, a witness shall be allowed the per diem allowance designated herein for each day required to travel in going to and returning from a trial. Mileage reimbursement to a witness traveling from out of state shall be the same as that allowed a state employee using a personal vehicle for the convenience of the state. In lieu of such mileage reimbursement, a witness traveling from out-of-state may be reimbursed for the cost of travel by common carrier, at a rate not to exceed the regular tourist fare charged the general public.