Idaho Code § 67-423

If in the event of an attack a legislator is unavailable, his emergency interim successor highest in order of succession who is not unavailable shall, except for the power and duty to appoint emergency successors, exercise the powers and assume the duties of such legislator. An emergency interim successor shall exercise these powers and assume these duties until the incumbent legislator, an emergency interim successor higher in order of succession, or a legislator appointed or elected and legally qualified can act. Each house of the legislature shall, in accordance with its own rules, determine who is entitled under the provisions of this act to exercise the powers and assume the duties of its members. All constitutional and statutory provisions pertaining to ouster of a legislator shall be applicable to an emergency interim successor who is exercising the powers and assuming the duties of a legislator.