Constitution of the State of Texas 1876 Art. 4, § 8. Convening Legislature on extraordinary occasions

(a) The Governor may, on extraordinary occasions, convene the Legislature at the seat of Government, or at a different place, in case that should be in possession of the public enemy or in case of the prevalence of disease threat. His proclamation therefor shall state specifically the purpose for which the Legislature is convened.

(b) The Governor shall convene the Legislature in special session to appoint presidential electors if the Governor determines that a reasonable likelihood exists that a final determination of the appointment of electors will not occur before the deadline prescribed by law to ascertain a conclusive determination of the appointment. The Legislature may not consider any subject other than the appointment of electors at that special session.