Tenn. Code Ann. § 24-2-105: Privilege against process

During the attendance of any person summoned as a witness, and during the time that such person is going to and returning from the place of such attendance, allowing one (1) day for every thirty (30) miles of travel, no writ, process, warrant, order, judgment, or decree in any civil cause, subpoena to testify as a witness only excepted, shall be served upon such person.