Tenn. Code Ann. § 39-11-612: Defense of third person

A person is justified in threatening or using force against another to protect a third person, if:

(1) Under the circumstances as the person reasonably believes them to be, the person would be justified under § 39-11-611 in threatening or using force to protect against the use or attempted use of unlawful force reasonably believed to be threatening the third person sought to be protected; and

(2) The person reasonably believes that the intervention is immediately necessary to protect the third person.