Texas Transportation Code - TRANSP § 545.053. Passing to the Left;  Return;  Being Passed

(1) shall pass to the left of the other vehicle at a safe distance;  and

(2) may not move back to the right side of the roadway until safely clear of the passed vehicle.

(1) shall, on audible signal, move or remain to the right in favor of the passing vehicle;  and

(2) may not accelerate until completely passed by the passing vehicle.