Tex. Local Government Code § 292.001

(a) The commissioners court of a county may purchase, construct, or provide by other means, including a lease or a lease with an option to purchase, or may reconstruct, improve, or equip a building or rooms, other than the courthouse, for the housing of county or district offices, county or district courts, justice of the peace courts, county records or equipment (including voting machines), or county jail facilities, or for the conducting of other public business, if the commissioners court determines that the additional building or rooms are necessary. The commissioners court may purchase and improve the necessary site for the building or rooms.

(b) Except as provided by this subsection and to the extent permitted under other law, the building or rooms must be located in the county seat. If the building or rooms are for housing a county or district court in buildings or rooms designated for that purpose, or for housing county jail facilities, the building or rooms may be located anywhere in the county at the discretion of the commissioners court.

(c) The commissioners court may lease or rent to any person any part of the building or rooms that are not necessary for the purposes described by Subsection (a).

(d) A justice of the peace court may not be housed or conducted in a building located outside the court's precinct except as provided by Section 27.051(f) or 27.0515, Government Code, or unless the justice of the peace court is situated in the county courthouse in a county with a population of at least 305,000 persons and the county seat of which is located in the Llano Estacado region of this state.