Conditions Requiring Motor Vehicle Ignition Interlock – Texas Code of Criminal Procedure Article 17.441
(a) Except as provided by Subsection (b), a magistrate shall require on release that a defendant charged with a subsequent offense under Sections 49.04-49.06, Penal Code, or an offense under Section 49.07 or 49.08 of that code:
(1) have installed on the motor vehicle owned by the defendant or on the vehicle most regularly driven by the defendant, a device that uses a deep-lung breath analysis mechanism to make impractical the operation of a motor vehicle if ethyl alcohol is detected in the breath of the operator; and
(2) not operate any motor vehicle unless the vehicle is equipped with that device.
(b) The magistrate may not require the installation of the device if the magistrate finds that to require the device would not be in the best interest of justice.
(c) If the defendant is required to have the device installed, the magistrate shall require that the defendant have the device installed on the appropriate motor vehicle, at the defendant's expense, before the 30th day after the date the defendant is released on bond.
(d) The magistrate may designate an appropriate agency to verify the installation of the device and to monitor the device. If the magistrate designates an agency under this subsection, in each month during which the agency verifies the installation of the device or provides a monitoring service the defendant shall pay a fee to the designated agency in the amount set by the magistrate. The defendant shall pay the initial fee at the time the agency verifies the installation of the device. In each subsequent month during which the defendant is required to pay a fee the defendant shall pay the fee on the first occasion in that month that the agency provides a monitoring service. The magistrate shall set the fee in an amount not to exceed $10 as determined by the county auditor, or by the commissioners court of the county if the county does not have a county auditor, to be sufficient to cover the cost incurred by the designated agency in conducting the verification or providing the monitoring service, as applicable in that county.