Texas Government Code - GOV'T § 304.008. Assumption of Powers and Duties

(a) If the governor has declared an emergency due to enemy attack or the immediate threat of enemy attack under Section 62, Article III, Texas Constitution, and the lieutenant governor or speaker of the house, as applicable, determines that a legislator is unavailable to serve when the legislature has convened or will convene, the lieutenant governor or speaker, as applicable, shall certify to the secretary of state that the legislator is unavailable. If the governor has declared an emergency due to enemy attack or the immediate threat of enemy attack under Section 62, Article III, Texas Constitution, and at the time and place the legislature is scheduled to convene the lieutenant governor or speaker is absent from the applicable house, a majority of the members of that house who are present may determine that a member of that house who is not present is unavailable and certify that determination to the secretary of state.

(b) If a legislator is certified to be unavailable under Subsection (a), the secretary of state shall notify the legislator's emergency interim successor highest in order of succession who is available that the emergency interim successor is entitled to exercise the powers and duties of the legislator who is unavailable. The secretary of state shall inform the emergency interim successor of the date, time, and place at which the legislature is meeting or will meet, as soon as that is known. If the emergency interim successor declines to serve or does not appear and begin to serve within a reasonable time as determined by the lieutenant governor or speaker of the house, as applicable, the secretary of state at the request of the lieutenant governor or speaker shall notify the emergency interim successor next in order of succession who is available that the emergency interim successor is entitled to exercise the powers and duties of the legislator who is unavailable.

(c) The emergency interim successor shall exercise the powers and assume the duties of the legislator whom the individual succeeds, except that the successor may not designate emergency interim successors or make revisions to a designation.

(d) The emergency interim successor exercises those powers and assumes those duties until the secretary of state notifies the successor that the incumbent legislator, an emergency interim successor higher in order of succession for the same position, or a legislator elected to the same position and legally qualified can act.

(e) Any dispute as to the qualification of an individual to exercise the powers and assume the duties of a legislator under this chapter shall be determined by the applicable house of the legislature as provided by Section 8, Article III, Texas Constitution.