Idaho Code § 28-3-119

In an action for breach of an obligation for which a third person is answerable over pursuant to this chapter or chapter 4[, title 28, Idaho Code], the defendant may give the third person written notice of the litigation, and the person notified may then give similar notice to any other person who is answerable over. If the notice states (i) that the person notified may come in and defend and (ii) that failure to do so will bind the person notified in an action later brought by the person giving the notice as to any determination of fact common to the two (2) litigations, the person notified is so bound unless after seasonable receipt of the notice the person notified does come in and defend.